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Re: [PATCH 2.22] Synchronize support/ infrastructure with master



On 04/04/2018 08:22 AM, Raphael Moreira Zinsly wrote:
> From: Arjun Shankar <arjun.is@lostca.se>
> 
> Sorry for that, with that backport the tests work fine.
> 
> -- >8 --
> 
> This commit updates the support/ subdirectory to
> commit 2714c5f3c95f90977167c1d21326d907fb76b419
> on the master branch and modifies Makeconfig,
> Rules, and extra-lib.mk accordingly.

Ah! I see now. This patch is dependent on the other later patch.

This looks fine. In the future please post a patch series so they
get reviewed together, or identify dependencies.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

> (cherry picked from commit 4c5785aa129a5d195fc1cd5c7fcd6f62c2b0ff0c)
> ---
>  Makeconfig                                 |   15 +-
>  Rules                                      |    3 +
>  extra-lib.mk                               |    5 +
>  scripts/backport-support.sh                |  110 +++
>  support/Makefile                           |  146 ++++
>  support/README                             |   29 +
>  support/README-testing.c                   |   19 +
>  support/capture_subprocess.h               |   61 ++
>  support/check.c                            |   57 ++
>  support/check.h                            |   94 +++
>  support/check_addrinfo.c                   |   42 +
>  support/check_dns_packet.c                 |   42 +
>  support/check_hostent.c                    |   42 +
>  support/check_netent.c                     |   42 +
>  support/check_nss.h                        |   42 +
>  support/delayed_exit.c                     |   55 ++
>  support/format_nss.h                       |   41 +
>  support/ignore_stderr.c                    |   38 +
>  support/namespace.h                        |   65 ++
>  support/oom_error.c                        |   29 +
>  support/resolv_test.c                      | 1202 ++++++++++++++++++++++++++++
>  support/resolv_test.h                      |  180 +++++
>  support/run_diff.h                         |   31 +
>  support/set_fortify_handler.c              |   34 +
>  support/support-xstat.c                    |   30 +
>  support/support.h                          |   74 ++
>  support/support_become_root.c              |   40 +
>  support/support_can_chroot.c               |   65 ++
>  support/support_capture_subprocess.c       |  108 +++
>  support/support_capture_subprocess_check.c |   67 ++
>  support/support_enter_network_namespace.c  |   75 ++
>  support/support_format_address_family.c    |   35 +
>  support/support_format_addrinfo.c          |  239 ++++++
>  support/support_format_dns_packet.c        |  222 +++++
>  support/support_format_herrno.c            |   45 ++
>  support/support_format_hostent.c           |   75 ++
>  support/support_format_netent.c            |   52 ++
>  support/support_isolate_in_subprocess.c    |   38 +
>  support/support_record_failure.c           |  106 +++
>  support/support_run_diff.c                 |   76 ++
>  support/support_shared_allocate.c          |   59 ++
>  support/support_test_main.c                |  423 ++++++++++
>  support/support_test_verify_impl.c         |   33 +
>  support/support_write_file_string.c        |   39 +
>  support/temp_file-internal.h               |   31 +
>  support/temp_file.c                        |  132 +++
>  support/temp_file.h                        |   37 +
>  support/test-driver.c                      |  156 ++++
>  support/test-driver.h                      |   74 ++
>  support/tst-support-namespace.c            |   34 +
>  support/tst-support_capture_subprocess.c   |  188 +++++
>  support/tst-support_format_dns_packet.c    |  101 +++
>  support/tst-support_record_failure-2.sh    |   69 ++
>  support/tst-support_record_failure.c       |  153 ++++
>  support/write_message.c                    |   29 +
>  support/xaccept.c                          |   32 +
>  support/xaccept4.c                         |   32 +
>  support/xasprintf.c                        |   36 +
>  support/xbind.c                            |   30 +
>  support/xcalloc.c                          |   34 +
>  support/xchroot.c                          |   28 +
>  support/xclose.c                           |   28 +
>  support/xconnect.c                         |   30 +
>  support/xdup2.c                            |   28 +
>  support/xfclose.c                          |   33 +
>  support/xfopen.c                           |   31 +
>  support/xfork.c                            |   32 +
>  support/xgetsockname.c                     |   30 +
>  support/xlisten.c                          |   30 +
>  support/xmalloc.c                          |   34 +
>  support/xmemstream.c                       |   42 +
>  support/xmemstream.h                       |   49 ++
>  support/xmkdir.c                           |   28 +
>  support/xmmap.c                            |   31 +
>  support/xmunmap.c                          |   28 +
>  support/xopen.c                            |   30 +
>  support/xpipe.c                            |   28 +
>  support/xpoll.c                            |   32 +
>  support/xpthread_attr_destroy.c            |   26 +
>  support/xpthread_attr_init.c               |   25 +
>  support/xpthread_attr_setdetachstate.c     |   27 +
>  support/xpthread_attr_setstacksize.c       |   26 +
>  support/xpthread_barrier_destroy.c         |   26 +
>  support/xpthread_barrier_init.c            |   27 +
>  support/xpthread_barrier_wait.c            |   28 +
>  support/xpthread_cancel.c                  |   25 +
>  support/xpthread_check_return.c            |   34 +
>  support/xpthread_cond_wait.c               |   26 +
>  support/xpthread_create.c                  |   29 +
>  support/xpthread_detach.c                  |   25 +
>  support/xpthread_join.c                    |   27 +
>  support/xpthread_mutex_consistent.c        |   26 +
>  support/xpthread_mutex_destroy.c           |   26 +
>  support/xpthread_mutex_init.c              |   26 +
>  support/xpthread_mutex_lock.c              |   25 +
>  support/xpthread_mutex_unlock.c            |   25 +
>  support/xpthread_mutexattr_destroy.c       |   26 +
>  support/xpthread_mutexattr_init.c          |   25 +
>  support/xpthread_mutexattr_setprotocol.c   |   26 +
>  support/xpthread_mutexattr_setpshared.c    |   26 +
>  support/xpthread_mutexattr_setrobust.c     |   26 +
>  support/xpthread_mutexattr_settype.c       |   26 +
>  support/xpthread_once.c                    |   25 +
>  support/xpthread_sigmask.c                 |   34 +
>  support/xpthread_spin_lock.c               |   25 +
>  support/xpthread_spin_unlock.c             |   25 +
>  support/xrealloc.c                         |   32 +
>  support/xrecvfrom.c                        |   33 +
>  support/xsendto.c                          |   35 +
>  support/xsetsockopt.c                      |   31 +
>  support/xsignal.h                          |   34 +
>  support/xsocket.c                          |   32 +
>  support/xsocket.h                          |   39 +
>  support/xstdio.h                           |   32 +
>  support/xstrdup.c                          |   30 +
>  support/xthread.h                          |   77 ++
>  support/xunistd.h                          |   56 ++
>  support/xwaitpid.c                         |   33 +
>  support/xwrite.c                           |   39 +
>  119 files changed, 7308 insertions(+), 3 deletions(-)
>  create mode 100644 scripts/backport-support.sh
>  create mode 100644 support/Makefile
>  create mode 100644 support/README
>  create mode 100644 support/README-testing.c
>  create mode 100644 support/capture_subprocess.h
>  create mode 100644 support/check.c
>  create mode 100644 support/check.h
>  create mode 100644 support/check_addrinfo.c
>  create mode 100644 support/check_dns_packet.c
>  create mode 100644 support/check_hostent.c
>  create mode 100644 support/check_netent.c
>  create mode 100644 support/check_nss.h
>  create mode 100644 support/delayed_exit.c
>  create mode 100644 support/format_nss.h
>  create mode 100644 support/ignore_stderr.c
>  create mode 100644 support/namespace.h
>  create mode 100644 support/oom_error.c
>  create mode 100644 support/resolv_test.c
>  create mode 100644 support/resolv_test.h
>  create mode 100644 support/run_diff.h
>  create mode 100644 support/set_fortify_handler.c
>  create mode 100644 support/support-xstat.c
>  create mode 100644 support/support.h
>  create mode 100644 support/support_become_root.c
>  create mode 100644 support/support_can_chroot.c
>  create mode 100644 support/support_capture_subprocess.c
>  create mode 100644 support/support_capture_subprocess_check.c
>  create mode 100644 support/support_enter_network_namespace.c
>  create mode 100644 support/support_format_address_family.c
>  create mode 100644 support/support_format_addrinfo.c
>  create mode 100644 support/support_format_dns_packet.c
>  create mode 100644 support/support_format_herrno.c
>  create mode 100644 support/support_format_hostent.c
>  create mode 100644 support/support_format_netent.c
>  create mode 100644 support/support_isolate_in_subprocess.c
>  create mode 100644 support/support_record_failure.c
>  create mode 100644 support/support_run_diff.c
>  create mode 100644 support/support_shared_allocate.c
>  create mode 100644 support/support_test_main.c
>  create mode 100644 support/support_test_verify_impl.c
>  create mode 100644 support/support_write_file_string.c
>  create mode 100644 support/temp_file-internal.h
>  create mode 100644 support/temp_file.c
>  create mode 100644 support/temp_file.h
>  create mode 100644 support/test-driver.c
>  create mode 100644 support/test-driver.h
>  create mode 100644 support/tst-support-namespace.c
>  create mode 100644 support/tst-support_capture_subprocess.c
>  create mode 100644 support/tst-support_format_dns_packet.c
>  create mode 100644 support/tst-support_record_failure-2.sh
>  create mode 100644 support/tst-support_record_failure.c
>  create mode 100644 support/write_message.c
>  create mode 100644 support/xaccept.c
>  create mode 100644 support/xaccept4.c
>  create mode 100644 support/xasprintf.c
>  create mode 100644 support/xbind.c
>  create mode 100644 support/xcalloc.c
>  create mode 100644 support/xchroot.c
>  create mode 100644 support/xclose.c
>  create mode 100644 support/xconnect.c
>  create mode 100644 support/xdup2.c
>  create mode 100644 support/xfclose.c
>  create mode 100644 support/xfopen.c
>  create mode 100644 support/xfork.c
>  create mode 100644 support/xgetsockname.c
>  create mode 100644 support/xlisten.c
>  create mode 100644 support/xmalloc.c
>  create mode 100644 support/xmemstream.c
>  create mode 100644 support/xmemstream.h
>  create mode 100644 support/xmkdir.c
>  create mode 100644 support/xmmap.c
>  create mode 100644 support/xmunmap.c
>  create mode 100644 support/xopen.c
>  create mode 100644 support/xpipe.c
>  create mode 100644 support/xpoll.c
>  create mode 100644 support/xpthread_attr_destroy.c
>  create mode 100644 support/xpthread_attr_init.c
>  create mode 100644 support/xpthread_attr_setdetachstate.c
>  create mode 100644 support/xpthread_attr_setstacksize.c
>  create mode 100644 support/xpthread_barrier_destroy.c
>  create mode 100644 support/xpthread_barrier_init.c
>  create mode 100644 support/xpthread_barrier_wait.c
>  create mode 100644 support/xpthread_cancel.c
>  create mode 100644 support/xpthread_check_return.c
>  create mode 100644 support/xpthread_cond_wait.c
>  create mode 100644 support/xpthread_create.c
>  create mode 100644 support/xpthread_detach.c
>  create mode 100644 support/xpthread_join.c
>  create mode 100644 support/xpthread_mutex_consistent.c
>  create mode 100644 support/xpthread_mutex_destroy.c
>  create mode 100644 support/xpthread_mutex_init.c
>  create mode 100644 support/xpthread_mutex_lock.c
>  create mode 100644 support/xpthread_mutex_unlock.c
>  create mode 100644 support/xpthread_mutexattr_destroy.c
>  create mode 100644 support/xpthread_mutexattr_init.c
>  create mode 100644 support/xpthread_mutexattr_setprotocol.c
>  create mode 100644 support/xpthread_mutexattr_setpshared.c
>  create mode 100644 support/xpthread_mutexattr_setrobust.c
>  create mode 100644 support/xpthread_mutexattr_settype.c
>  create mode 100644 support/xpthread_once.c
>  create mode 100644 support/xpthread_sigmask.c
>  create mode 100644 support/xpthread_spin_lock.c
>  create mode 100644 support/xpthread_spin_unlock.c
>  create mode 100644 support/xrealloc.c
>  create mode 100644 support/xrecvfrom.c
>  create mode 100644 support/xsendto.c
>  create mode 100644 support/xsetsockopt.c
>  create mode 100644 support/xsignal.h
>  create mode 100644 support/xsocket.c
>  create mode 100644 support/xsocket.h
>  create mode 100644 support/xstdio.h
>  create mode 100644 support/xstrdup.c
>  create mode 100644 support/xthread.h
>  create mode 100644 support/xunistd.h
>  create mode 100644 support/xwaitpid.c
>  create mode 100644 support/xwrite.c
> 
> diff --git a/Makeconfig b/Makeconfig
> index f136b88..b5d100b 100644
> --- a/Makeconfig
> +++ b/Makeconfig
> @@ -395,6 +395,9 @@ ifndef after-link
>  after-link =
>  endif
>  
> +# Additional libraries to link into every test.
> +link-extra-libs-tests = $(libsupport)
> +
>  # Command for linking PIE programs with the C library.
>  ifndef +link-pie
>  +link-pie-before-libc = $(CC) -pie -Wl,-O1 -nostdlib -nostartfiles -o $@ \
> @@ -504,7 +507,7 @@ link-libc = $(link-libc-rpath-link) $(link-libc-before-gnulib) $(gnulib)
>  link-libc-tests = $(link-libc-tests-rpath-link) \
>  		  $(link-libc-before-gnulib) $(gnulib-tests)
>  # This is how to find at build-time things that will be installed there.
> -rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec
> +rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec support
>  rpath-link = \
>  $(common-objdir):$(subst $(empty) ,:,$(patsubst ../$(subdir),.,$(rpath-dirs:%=$(common-objpfx)%)))
>  else
> @@ -851,7 +854,7 @@ libio-include = -I$(..)libio
>  # List of non-library modules that we build.
>  built-modules = iconvprogs iconvdata ldconfig lddlibc4 libmemusage \
>  		libSegFault libpcprofile librpcsvc locale-programs \
> -		memusagestat nonlib nscd extramodules libnldbl
> +		memusagestat nonlib nscd extramodules libnldbl libsupport
>  
>  in-module = $(subst -,_,$(firstword $(libof-$(basename $(@F))) \
>  				    $(libof-$(<F)) \
> @@ -1089,6 +1092,12 @@ libm = $(common-objpfx)math/libm.a
>  libmvec = $(common-objpfx)mathvec/libmvec.a
>  endif
>  
> +ifeq ($(build-shared),yes)
> +libsupport = $(common-objpfx)support/libsupport_nonshared.a
> +else
> +libsupport = $(common-objpfx)support/libsupport.a
> +endif
> +
>  # These are the subdirectories containing the library source.  The order
>  # is more or less arbitrary.  The sorting step will take care of the
>  # dependencies.
> @@ -1096,7 +1105,7 @@ all-subdirs = csu assert ctype locale intl catgets math setjmp signal	    \
>  	      stdlib stdio-common libio malloc string wcsmbs time dirent    \
>  	      grp pwd posix io termios resource misc socket sysvipc gmon    \
>  	      gnulib iconv iconvdata wctype manual shadow gshadow po argp   \
> -	      crypt localedata timezone rt conform debug mathvec	    \
> +	      crypt localedata timezone rt conform debug mathvec support    \
>  	      $(add-on-subdirs) dlfcn elf
>  
>  ifndef avoid-generated
> diff --git a/Rules b/Rules
> index e237d03..7c5777c 100644
> --- a/Rules
> +++ b/Rules
> @@ -149,6 +149,7 @@ endif
>  
>  ifneq "$(strip $(binaries-shared-tests))" ""
>  $(addprefix $(objpfx),$(binaries-shared-tests)): %: %.o \
> +  $(link-extra-libs-tests) \
>    $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
>    $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
>  	$(+link-tests)
> @@ -156,6 +157,7 @@ endif
>  
>  ifneq "$(strip $(binaries-pie-tests))" ""
>  $(addprefix $(objpfx),$(binaries-pie-tests)): %: %.o \
> +  $(link-extra-libs-tests) \
>    $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
>    $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
>  	$(+link-pie-tests)
> @@ -177,6 +179,7 @@ endif
>  
>  ifneq "$(strip $(binaries-static-tests))" ""
>  $(addprefix $(objpfx),$(binaries-static-tests)): %: %.o \
> +  $(link-extra-libs-tests) \
>    $(sort $(filter $(common-objpfx)lib%,$(link-libc-static-tests))) \
>    $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
>  	$(+link-static-tests)
> diff --git a/extra-lib.mk b/extra-lib.mk
> index b10748d..2552049 100644
> --- a/extra-lib.mk
> +++ b/extra-lib.mk
> @@ -5,6 +5,9 @@
>  # The variable $($(lib)-routines) defines the list of modules
>  # to be included in that library.  A sysdep Makefile can add to
>  # $(lib)-sysdep_routines to include additional modules.
> +#
> +# Libraries listed in $(extra-libs-noinstall) are built, but not
> +# installed.
>  
>  lib := $(firstword $(extra-libs-left))
>  extra-libs-left := $(filter-out $(lib),$(extra-libs-left))
> @@ -28,7 +31,9 @@ extra-objs := $(extra-objs)
>  all-$(lib)-routines := $($(lib)-routines) $($(lib)-sysdep_routines)
>  
>  # Add each flavor of library to the lists of things to build and install.
> +ifeq (,$(filter $(lib), $(extra-libs-noinstall)))
>  install-lib += $(foreach o,$(object-suffixes-$(lib)),$(lib:lib%=$(libtype$o)))
> +endif
>  extra-objs += $(foreach o,$(filter-out .os .oS,$(object-suffixes-$(lib))),\
>  			$(patsubst %,%$o,$(filter-out \
>  					   $($(lib)-shared-only-routines),\
> diff --git a/scripts/backport-support.sh b/scripts/backport-support.sh
> new file mode 100644
> index 0000000..2ece7ce
> --- /dev/null
> +++ b/scripts/backport-support.sh
> @@ -0,0 +1,110 @@
> +#!/bin/bash
> +# Create a patch which backports the support/ subdirectory.
> +# Copyright (C) 2017 Free Software Foundation, Inc.
> +# This file is part of the GNU C Library.
> +
> +# The GNU C Library is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU Lesser General Public
> +# License as published by the Free Software Foundation; either
> +# version 2.1 of the License, or (at your option) any later version.
> +
> +# The GNU C Library is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +# Lesser General Public License for more details.
> +
> +# You should have received a copy of the GNU Lesser General Public
> +# License along with the GNU C Library; if not, see
> +# <http://www.gnu.org/licenses/>.
> +
> +# This script does not backport the Makefile tweaks outside the
> +# support/ directory (which need to be backported separately), or the
> +# changes to test-skeleton.c (which should not be backported).
> +
> +set -e
> +
> +export LC_ALL=C
> +export GIT_CONFIG=/dev/null
> +export GTT_CONFIG_NOSYSTEM=0
> +export GIT_PAGER=
> +
> +usage () {
> +    cat >&2 <<EOF
> +usage: $0 {patch|commit}
> +EOF
> +    exit 1
> +}
> +
> +if test $# -ne 1 ; then
> +    usage
> +fi
> +
> +command="$1"
> +
> +case "$command" in
> +    patch|commit)
> +    ;;
> +    *)
> +	usage
> +	;;
> +esac
> +
> +# The upstream branch to work on.
> +branch=origin/master
> +
> +# The commit which added the support/ directory.
> +initial_commit=c23de0aacbeaa7a091609b35764bed931475a16d
> +
> +# We backport the support directory and this script.  Directories need
> +# to end in a /.
> +patch_targets="support/ scripts/backport-support.sh"
> +
> +latest_commit="$(git log --max-count=1 --pretty=format:%H "$branch" -- \
> +  $patch_targets)"
> +
> +# Simplify the branch name somewhat for reporting.
> +branch_name="$(echo "$branch" | sed s,^origin/,,)"
> +
> +command_patch () {
> +    cat <<EOF
> +This patch creates the contents of the support/ directory up to this
> +upstream commit on the $branch_name branch:
> +
> +EOF
> +    git log --max-count=1 "$latest_commit"
> +    echo
> +    git diff "$initial_commit"^.."$latest_commit" $patch_targets
> +    echo "# Before applying the patch, run this command:" >&2
> +    echo "# rm -rf $patch_targets" >&2
> +}
> +
> +command_commit () {
> +    git status --porcelain | while read line ; do
> +	echo "error: working copy is not clean, cannot commit" >&2
> +	exit 1
> +    done
> +    for path in $patch_targets; do
> +	echo "# Processing $path" >&2
> +	case "$path" in
> +	    [a-zA-Z0-9]*/)
> +		# Directory.
> +		git rm --cached --ignore-unmatch -r "$path"
> +		rm -rf "$path"
> +		git read-tree --prefix="$path" "$latest_commit":"$path"
> +		git checkout "$path"
> +		;;
> +	    *)
> +		# File.
> +		git show "$latest_commit":"$path" > "$path"
> +		git add "$path"
> +	esac
> +    done
> +    git commit -m "Synchronize support/ infrastructure with $branch_name
> +
> +This commit updates the support/ subdirectory to
> +commit $latest_commit
> +on the $branch_name branch.
> +"
> +}
> +
> +command_$command
> diff --git a/support/Makefile b/support/Makefile
> new file mode 100644
> index 0000000..20b0343
> --- /dev/null
> +++ b/support/Makefile
> @@ -0,0 +1,146 @@
> +# Makefile for support library, used only at build and test time
> +# Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +# This file is part of the GNU C Library.
> +
> +# The GNU C Library is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU Lesser General Public
> +# License as published by the Free Software Foundation; either
> +# version 2.1 of the License, or (at your option) any later version.
> +
> +# The GNU C Library is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +# Lesser General Public License for more details.
> +
> +# You should have received a copy of the GNU Lesser General Public
> +# License along with the GNU C Library; if not, see
> +# <http://www.gnu.org/licenses/>.
> +
> +subdir := support
> +
> +include ../Makeconfig
> +
> +extra-libs := libsupport
> +extra-libs-others = $(extra-libs)
> +extra-libs-noinstall := $(extra-libs)
> +
> +libsupport-routines = \
> +  check \
> +  check_addrinfo \
> +  check_dns_packet \
> +  check_hostent \
> +  check_netent \
> +  delayed_exit \
> +  ignore_stderr \
> +  oom_error \
> +  resolv_test \
> +  set_fortify_handler \
> +  support-xstat \
> +  support_become_root \
> +  support_can_chroot \
> +  support_capture_subprocess \
> +  support_capture_subprocess_check \
> +  support_enter_network_namespace \
> +  support_format_address_family \
> +  support_format_addrinfo \
> +  support_format_dns_packet \
> +  support_format_herrno \
> +  support_format_hostent \
> +  support_format_netent \
> +  support_isolate_in_subprocess \
> +  support_record_failure \
> +  support_run_diff \
> +  support_shared_allocate \
> +  support_write_file_string \
> +  support_test_main \
> +  support_test_verify_impl \
> +  temp_file \
> +  write_message \
> +  xaccept \
> +  xaccept4 \
> +  xasprintf \
> +  xbind \
> +  xcalloc \
> +  xchroot \
> +  xclose \
> +  xconnect \
> +  xdup2 \
> +  xfclose \
> +  xfopen \
> +  xfork \
> +  xgetsockname \
> +  xlisten \
> +  xmalloc \
> +  xmemstream \
> +  xmkdir \
> +  xmmap \
> +  xmunmap \
> +  xopen \
> +  xpipe \
> +  xpoll \
> +  xpthread_attr_destroy \
> +  xpthread_attr_init \
> +  xpthread_attr_setdetachstate \
> +  xpthread_attr_setstacksize \
> +  xpthread_barrier_destroy \
> +  xpthread_barrier_init \
> +  xpthread_barrier_wait \
> +  xpthread_cancel \
> +  xpthread_check_return \
> +  xpthread_cond_wait \
> +  xpthread_create \
> +  xpthread_detach \
> +  xpthread_join \
> +  xpthread_mutex_consistent \
> +  xpthread_mutex_destroy \
> +  xpthread_mutex_init \
> +  xpthread_mutex_lock \
> +  xpthread_mutex_unlock \
> +  xpthread_mutexattr_destroy \
> +  xpthread_mutexattr_init \
> +  xpthread_mutexattr_setprotocol \
> +  xpthread_mutexattr_setpshared \
> +  xpthread_mutexattr_setrobust \
> +  xpthread_mutexattr_settype \
> +  xpthread_once \
> +  xpthread_sigmask \
> +  xpthread_spin_lock \
> +  xpthread_spin_unlock \
> +  xrealloc \
> +  xrecvfrom \
> +  xsendto \
> +  xsetsockopt \
> +  xsocket \
> +  xstrdup \
> +  xwaitpid \
> +  xwrite \
> +
> +libsupport-static-only-routines := $(libsupport-routines)
> +# Only build one variant of the library.
> +libsupport-inhibit-o := .os
> +ifeq ($(build-shared),yes)
> +libsupport-inhibit-o += .o
> +endif
> +
> +tests = \
> +  README-testing \
> +  tst-support-namespace \
> +  tst-support_capture_subprocess \
> +  tst-support_format_dns_packet \
> +  tst-support_record_failure \
> +
> +ifeq ($(run-built-tests),yes)
> +tests-special = \
> +  $(objpfx)tst-support_record_failure-2.out
> +
> +$(objpfx)tst-support_record_failure-2.out: tst-support_record_failure-2.sh \
> +  $(objpfx)tst-support_record_failure
> +	$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
> +	  '$(run-program-env)' '$(test-program-prefix-after-env)' \
> +	  > $@; \
> +	$(evaluate-test)
> +endif
> +
> +$(objpfx)tst-support_format_dns_packet: $(common-objpfx)resolv/libresolv.so
> +
> +include ../Rules
> diff --git a/support/README b/support/README
> new file mode 100644
> index 0000000..476cfcd
> --- /dev/null
> +++ b/support/README
> @@ -0,0 +1,29 @@
> +This subdirectory contains infrastructure which is not put into
> +installed libraries, but may be linked into programs (installed or
> +not) and tests.
> +
> +# Error-checking wrappers
> +
> +These wrappers test for error return codes an terminate the process on
> +error.  They are declared in these header files:
> +
> +* support.h
> +* xsignal.h
> +* xthread.h
> +
> +In general, new wrappers should be added to support.h if possible.
> +However, support.h must remain fully compatible with C90 and therefore
> +cannot include headers which use identifers not reserved in C90.  If
> +the wrappers need additional types, additional headers such as
> +signal.h need to be introduced.
> +
> +# Test framework
> +
> +The test framework provides a main program for tests, including a
> +timeout for hanging tests.  See README-testing.c for a minimal
> +example, and test-driver.c for details how to use it.  The following
> +header files provide related declarations:
> +
> +* check.h
> +* temp_file.h
> +* test-driver.h
> diff --git a/support/README-testing.c b/support/README-testing.c
> new file mode 100644
> index 0000000..9d289c3
> --- /dev/null
> +++ b/support/README-testing.c
> @@ -0,0 +1,19 @@
> +/* This file contains an example test case which shows minimal use of
> +   the test framework.  Additional testing hooks are described in
> +   <support/test-driver.c>.  */
> +
> +/* This function will be called from the test driver.  */
> +static int
> +do_test (void)
> +{
> +  if (3 == 5)
> +    /* Indicate failure.  */
> +    return 1;
> +  else
> +    /* Indicate success.  */
> +    return 0;
> +}
> +
> +/* This file references do_test above and contains the definition of
> +   the main function.  */
> +#include <support/test-driver.c>
> diff --git a/support/capture_subprocess.h b/support/capture_subprocess.h
> new file mode 100644
> index 0000000..43caf9b
> --- /dev/null
> +++ b/support/capture_subprocess.h
> @@ -0,0 +1,61 @@
> +/* Capture output from a subprocess.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_CAPTURE_SUBPROCESS_H
> +#define SUPPORT_CAPTURE_SUBPROCESS_H
> +
> +#include <support/xmemstream.h>
> +
> +struct support_capture_subprocess
> +{
> +  struct xmemstream out;
> +  struct xmemstream err;
> +  int status;
> +};
> +
> +/* Invoke CALLBACK (CLOSURE) in a subprocess and capture standard
> +   output, standard error, and the exit status.  The out.buffer and
> +   err.buffer members in the result are null-terminated strings which
> +   can be examined by the caller (out.out and err.out are NULL).  */
> +struct support_capture_subprocess support_capture_subprocess
> +  (void (*callback) (void *), void *closure);
> +
> +/* Deallocate the subprocess data captured by
> +   support_capture_subprocess.  */
> +void support_capture_subprocess_free (struct support_capture_subprocess *);
> +
> +enum support_capture_allow
> +{
> +  /* No output is allowed.  */
> +  sc_allow_none = 0x01,
> +  /* Output to stdout is permitted.  */
> +  sc_allow_stdout = 0x02,
> +  /* Output to standard error is permitted.  */
> +  sc_allow_stderr = 0x04,
> +};
> +
> +/* Check that the subprocess exited with STATUS and that only the
> +   allowed outputs happened.  ALLOWED is a combination of
> +   support_capture_allow flags.  Report errors under the CONTEXT
> +   message.  */
> +void support_capture_subprocess_check (struct support_capture_subprocess *,
> +                                       const char *context, int status,
> +                                       int allowed)
> +  __attribute__ ((nonnull (1, 2)));
> +
> +#endif /* SUPPORT_CAPTURE_SUBPROCESS_H */
> diff --git a/support/check.c b/support/check.c
> new file mode 100644
> index 0000000..592f2bc
> --- /dev/null
> +++ b/support/check.c
> @@ -0,0 +1,57 @@
> +/* Support code for reporting test results.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/test-driver.h>
> +
> +static void
> +print_failure (const char *file, int line, const char *format, va_list ap)
> +{
> +  printf ("error: %s:%d: ", file, line);
> +  vprintf (format, ap);
> +  puts ("");
> +}
> +
> +int
> +support_print_failure_impl (const char *file, int line,
> +                            const char *format, ...)
> +{
> +  support_record_failure ();
> +  va_list ap;
> +  va_start (ap, format);
> +  print_failure (file, line, format, ap);
> +  va_end (ap);
> +  return 1;
> +}
> +
> +void
> +support_exit_failure_impl (int status, const char *file, int line,
> +                           const char *format, ...)
> +{
> +  if (status != EXIT_SUCCESS && status != EXIT_UNSUPPORTED)
> +    support_record_failure ();
> +  va_list ap;
> +  va_start (ap, format);
> +  print_failure (file, line, format, ap);
> +  va_end (ap);
> +  exit (status);
> +}
> diff --git a/support/check.h b/support/check.h
> new file mode 100644
> index 0000000..1d244a3
> --- /dev/null
> +++ b/support/check.h
> @@ -0,0 +1,94 @@
> +/* Functionality for reporting test results.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_CHECK_H
> +#define SUPPORT_CHECK_H
> +
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Record a test failure, print the failure message to standard output
> +   and return 1.  */
> +#define FAIL_RET(...) \
> +  return support_print_failure_impl (__FILE__, __LINE__, __VA_ARGS__)
> +
> +/* Print the failure message and terminate the process with STATUS.
> +   Record a the process as failed if STATUS is neither EXIT_SUCCESS
> +   nor EXIT_UNSUPPORTED.  */
> +#define FAIL_EXIT(status, ...) \
> +  support_exit_failure_impl (status, __FILE__, __LINE__, __VA_ARGS__)
> +
> +/* Record a test failure, print the failure message and terminate with
> +   exit status 1.  */
> +#define FAIL_EXIT1(...) \
> +  support_exit_failure_impl (1, __FILE__, __LINE__, __VA_ARGS__)
> +
> +/* Print failure message and terminate with as unsupported test (exit
> +   status of 77).  */
> +#define FAIL_UNSUPPORTED(...) \
> +  support_exit_failure_impl (77, __FILE__, __LINE__, __VA_ARGS__)
> +
> +/* Record a test failure (but continue executing) if EXPR evaluates to
> +   false.  */
> +#define TEST_VERIFY(expr)                                       \
> +  ({                                                            \
> +    if (expr)                                                   \
> +      ;                                                         \
> +    else                                                        \
> +      support_test_verify_impl (-1, __FILE__, __LINE__, #expr); \
> +  })
> +
> +/* Record a test failure and exit if EXPR evaluates to false.  */
> +#define TEST_VERIFY_EXIT(expr)                                  \
> +  ({                                                            \
> +    if (expr)                                                   \
> +      ;                                                         \
> +    else                                                        \
> +      support_test_verify_impl (1, __FILE__, __LINE__, #expr);  \
> +  })
> +
> +int support_print_failure_impl (const char *file, int line,
> +                                const char *format, ...)
> +  __attribute__ ((nonnull (1), format (printf, 3, 4)));
> +void support_exit_failure_impl (int exit_status,
> +                                const char *file, int line,
> +                                const char *format, ...)
> +  __attribute__ ((noreturn, nonnull (2), format (printf, 4, 5)));
> +void support_test_verify_impl (int status, const char *file, int line,
> +                               const char *expr);
> +
> +/* Record a test failure.  This function returns and does not
> +   terminate the process.  The failure counter is stored in a shared
> +   memory mapping, so that failures reported in child processes are
> +   visible to the parent process and test driver.  This function
> +   depends on initialization by an ELF constructor, so it can only be
> +   invoked after the test driver has run.  Note that this function
> +   does not support reporting failures from a DSO.  */
> +void support_record_failure (void);
> +
> +/* Internal function called by the test driver.  */
> +int support_report_failure (int status)
> +  __attribute__ ((weak, warn_unused_result));
> +
> +/* Internal function used to test the failure recording framework.  */
> +void support_record_failure_reset (void);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_CHECK_H */
> diff --git a/support/check_addrinfo.c b/support/check_addrinfo.c
> new file mode 100644
> index 0000000..55895ac
> --- /dev/null
> +++ b/support/check_addrinfo.c
> @@ -0,0 +1,42 @@
> +/* Compare struct addrinfo values against a formatted string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check_nss.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/format_nss.h>
> +#include <support/run_diff.h>
> +
> +void
> +check_addrinfo (const char *query_description, struct addrinfo *ai, int ret,
> +                const char *expected)
> +{
> +  char *formatted = support_format_addrinfo (ai, ret);
> +  if (strcmp (formatted, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: addrinfo comparison failure\n");
> +      if (query_description != NULL)
> +        printf ("query: %s\n", query_description);
> +      support_run_diff ("expected", expected,
> +                        "actual", formatted);
> +    }
> +  free (formatted);
> +}
> diff --git a/support/check_dns_packet.c b/support/check_dns_packet.c
> new file mode 100644
> index 0000000..d2a31be
> --- /dev/null
> +++ b/support/check_dns_packet.c
> @@ -0,0 +1,42 @@
> +/* Check that a DNS packet buffer has the expected contents.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check_nss.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/format_nss.h>
> +#include <support/run_diff.h>
> +
> +void
> +check_dns_packet (const char *query_description,
> +                  const unsigned char *buffer, size_t length,
> +                  const char *expected)
> +{
> +  char *formatted = support_format_dns_packet (buffer, length);
> +  if (strcmp (formatted, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: packet comparison failure\n");
> +      if (query_description != NULL)
> +        printf ("query: %s\n", query_description);
> +      support_run_diff ("expected", expected, "actual", formatted);
> +    }
> +  free (formatted);
> +}
> diff --git a/support/check_hostent.c b/support/check_hostent.c
> new file mode 100644
> index 0000000..890d672
> --- /dev/null
> +++ b/support/check_hostent.c
> @@ -0,0 +1,42 @@
> +/* Compare struct hostent values against a formatted string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check_nss.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/format_nss.h>
> +#include <support/run_diff.h>
> +
> +void
> +check_hostent (const char *query_description, struct hostent *h,
> +               const char *expected)
> +{
> +  char *formatted = support_format_hostent (h);
> +  if (strcmp (formatted, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: hostent comparison failure\n");
> +      if (query_description != NULL)
> +        printf ("query: %s\n", query_description);
> +      support_run_diff ("expected", expected,
> +                        "actual", formatted);
> +    }
> +  free (formatted);
> +}
> diff --git a/support/check_netent.c b/support/check_netent.c
> new file mode 100644
> index 0000000..daa3083
> --- /dev/null
> +++ b/support/check_netent.c
> @@ -0,0 +1,42 @@
> +/* Compare struct netent values against a formatted string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check_nss.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/format_nss.h>
> +#include <support/run_diff.h>
> +
> +void
> +check_netent (const char *query_description, struct netent *e,
> +              const char *expected)
> +{
> +  char *formatted = support_format_netent (e);
> +  if (strcmp (formatted, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: netent comparison failure\n");
> +      if (query_description != NULL)
> +        printf ("query: %s\n", query_description);
> +      support_run_diff ("expected", expected,
> +                        "actual", formatted);
> +    }
> +  free (formatted);
> +}
> diff --git a/support/check_nss.h b/support/check_nss.h
> new file mode 100644
> index 0000000..2893f2c
> --- /dev/null
> +++ b/support/check_nss.h
> @@ -0,0 +1,42 @@
> +/* Test verification functions for NSS- and DNS-related data.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_CHECK_NSS_H
> +#define SUPPORT_CHECK_NSS_H
> +
> +#include <netdb.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Compare the data structures against the expected values (which have
> +   to be formatted according to the support_format_* functions in
> +   <support/format_nss.h>).  If there is a difference, a delayed test
> +   failure is recorded, and a diff is written to standard output.  */
> +void check_addrinfo (const char *query_description,
> +                     struct addrinfo *, int ret, const char *expected);
> +void check_dns_packet (const char *query_description,
> +                       const unsigned char *, size_t, const char *expected);
> +void check_hostent (const char *query_description,
> +                    struct hostent *, const char *expected);
> +void check_netent (const char *query_description,
> +                   struct netent *, const char *expected);
> +
> +__END_DECLS
> +
> +#endif  /* SUPPORT_CHECK_NSS_H */
> diff --git a/support/delayed_exit.c b/support/delayed_exit.c
> new file mode 100644
> index 0000000..67442f9
> --- /dev/null
> +++ b/support/delayed_exit.c
> @@ -0,0 +1,55 @@
> +/* Time-triggered process termination.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +#include <support/xsignal.h>
> +
> +#include <stdint.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <time.h>
> +
> +static void *
> +delayed_exit_thread (void *seconds_as_ptr)
> +{
> +  int seconds = (uintptr_t) seconds_as_ptr;
> +  struct timespec delay = { seconds, 0 };
> +  struct timespec remaining = { 0 };
> +  if (nanosleep (&delay, &remaining) != 0)
> +    FAIL_EXIT1 ("nanosleep: %m");
> +  /* Exit the process sucessfully.  */
> +  exit (0);
> +  return NULL;
> +}
> +
> +void
> +delayed_exit (int seconds)
> +{
> +  /* Create the new thread with all signals blocked.  */
> +  sigset_t all_blocked;
> +  sigfillset (&all_blocked);
> +  sigset_t old_set;
> +  xpthread_sigmask (SIG_SETMASK, &all_blocked, &old_set);
> +  /* Create a detached thread. */
> +  pthread_t thr = xpthread_create
> +    (NULL, delayed_exit_thread, (void *) (uintptr_t) seconds);
> +  xpthread_detach (thr);
> +  /* Restore the original signal mask.  */
> +  xpthread_sigmask (SIG_SETMASK, &old_set, NULL);
> +}
> diff --git a/support/format_nss.h b/support/format_nss.h
> new file mode 100644
> index 0000000..fb4597c
> --- /dev/null
> +++ b/support/format_nss.h
> @@ -0,0 +1,41 @@
> +/* String formatting functions for NSS- and DNS-related data.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_FORMAT_NSS_H
> +#define SUPPORT_FORMAT_NSS_H
> +
> +#include <netdb.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* The following functions format their arguments as human-readable
> +   strings (which can span multiple lines).  The caller must free the
> +   returned buffer.  For NULL pointers or failure status arguments,
> +   error variables such as h_errno and errno are included in the
> +   result.  */
> +char *support_format_address_family (int);
> +char *support_format_addrinfo (struct addrinfo *, int ret);
> +char *support_format_dns_packet (const unsigned char *buffer, size_t length);
> +char *support_format_herrno (int);
> +char *support_format_hostent (struct hostent *);
> +char *support_format_netent (struct netent *);
> +
> +__END_DECLS
> +
> +#endif  /* SUPPORT_FORMAT_NSS_H */
> diff --git a/support/ignore_stderr.c b/support/ignore_stderr.c
> new file mode 100644
> index 0000000..7b77a2c
> --- /dev/null
> +++ b/support/ignore_stderr.c
> @@ -0,0 +1,38 @@
> +/* Avoid all the buffer overflow messages on stderr.
> +   Copyright (C) 2015-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <fcntl.h>
> +#include <paths.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +
> +void
> +ignore_stderr (void)
> +{
> +  int fd = open (_PATH_DEVNULL, O_WRONLY);
> +  if (fd == -1)
> +    close (STDERR_FILENO);
> +  else
> +    {
> +      dup2 (fd, STDERR_FILENO);
> +      close (fd);
> +    }
> +  setenv ("LIBC_FATAL_STDERR_", "1", 1);
> +}
> diff --git a/support/namespace.h b/support/namespace.h
> new file mode 100644
> index 0000000..e1ccaa1
> --- /dev/null
> +++ b/support/namespace.h
> @@ -0,0 +1,65 @@
> +/* Entering namespaces for test case isolation.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_NAMESPACE_H
> +#define SUPPORT_NAMESPACE_H
> +
> +#include <stdbool.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Attempts to become root (or acquire root-like privileges), possibly
> +   with the help of user namespaces.  Return true if (restricted) root
> +   privileges could be attained in some way.  Print diagnostics to
> +   standard output.
> +
> +   Note that this function generally has to be called before a process
> +   becomes multi-threaded, otherwise it may fail with insufficient
> +   privileges on systems which would support this operation for
> +   single-threaded processes.  */
> +bool support_become_root (void);
> +
> +/* Return true if this process can perform a chroot operation.  In
> +   general, this is only possible if support_become_root has been
> +   called.  Note that the actual test is performed in a subprocess,
> +   after fork, so that the file system root of the original process is
> +   not changed.  */
> +bool support_can_chroot (void);
> +
> +/* Enter a network namespace (and a UTS namespace if possible) and
> +   configure the loopback interface.  Return true if a network
> +   namespace could be created.  Print diagnostics to standard output.
> +   If a network namespace could be created, but networking in it could
> +   not be configured, terminate the process.  It is recommended to
> +   call support_become_root before this function so that the process
> +   has sufficient privileges.  */
> +bool support_enter_network_namespace (void);
> +
> +/* Return true if support_enter_network_namespace managed to enter a
> +   UTS namespace.  */
> +bool support_in_uts_namespace (void);
> +
> +/* Invoke CALLBACK (CLOSURE) in a subprocess created using fork.
> +   Terminate the calling process if the subprocess exits with a
> +   non-zero exit status.  */
> +void support_isolate_in_subprocess (void (*callback) (void *), void *closure);
> +
> +__END_DECLS
> +
> +#endif
> diff --git a/support/oom_error.c b/support/oom_error.c
> new file mode 100644
> index 0000000..7816978
> --- /dev/null
> +++ b/support/oom_error.c
> @@ -0,0 +1,29 @@
> +/* Reporting out-of-memory errors.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void
> +oom_error (const char *function, size_t size)
> +{
> +  printf ("%s: unable to allocate %zu bytes: %m\n", function, size);
> +  exit (1);
> +}
> diff --git a/support/resolv_test.c b/support/resolv_test.c
> new file mode 100644
> index 0000000..050cd71
> --- /dev/null
> +++ b/support/resolv_test.c
> @@ -0,0 +1,1202 @@
> +/* DNS test framework and libresolv redirection.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/resolv_test.h>
> +
> +#include <arpa/inet.h>
> +#include <errno.h>
> +#include <fcntl.h>
> +#include <nss.h>
> +#include <resolv.h>
> +#include <search.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/namespace.h>
> +#include <support/support.h>
> +#include <support/test-driver.h>
> +#include <support/xsocket.h>
> +#include <support/xthread.h>
> +#include <support/xunistd.h>
> +#include <sys/uio.h>
> +#include <unistd.h>
> +
> +/* Response builder.  */
> +
> +enum
> +  {
> +    max_response_length = 65536
> +  };
> +
> +/* List of pointers to be freed.  The hash table implementation
> +   (struct hsearch_data) does not provide a way to deallocate all
> +   objects, so this approach is used to avoid memory leaks.  */
> +struct to_be_freed
> +{
> +  struct to_be_freed *next;
> +  void *ptr;
> +};
> +
> +struct resolv_response_builder
> +{
> +  const unsigned char *query_buffer;
> +  size_t query_length;
> +
> +  size_t offset;                /* Bytes written so far in buffer.  */
> +  ns_sect section;              /* Current section in the DNS packet.  */
> +  unsigned int truncate_bytes;  /* Bytes to remove at end of response. */
> +  bool drop;                    /* Discard generated response.  */
> +  bool close;                   /* Close TCP client connection.  */
> +
> +  /* Offset of the two-byte RDATA length field in the currently
> +     written RDATA sub-structure.  0 if no RDATA is being written.  */
> +  size_t current_rdata_offset;
> +
> +  /* Hash table for locating targets for label compression.  */
> +  struct hsearch_data compression_offsets;
> +  /* List of pointers which need to be freed.  Used for domain names
> +     involved in label compression.  */
> +  struct to_be_freed *to_be_freed;
> +
> +  /* Must be last.  Not zeroed for performance reasons.  */
> +  unsigned char buffer[max_response_length];
> +};
> +
> +/* Response builder. */
> +
> +/* Add a pointer to the list of pointers to be freed when B is
> +   deallocated.  */
> +static void
> +response_push_pointer_to_free (struct resolv_response_builder *b, void *ptr)
> +{
> +  if (ptr == NULL)
> +    return;
> +  struct to_be_freed *e = xmalloc (sizeof (*e));
> +  *e = (struct to_be_freed) {b->to_be_freed, ptr};
> +  b->to_be_freed = e;
> +}
> +
> +void
> +resolv_response_init (struct resolv_response_builder *b,
> +                      struct resolv_response_flags flags)
> +{
> +  if (b->offset > 0)
> +    FAIL_EXIT1 ("response_init: called at offset %zu", b->offset);
> +  if (b->query_length < 12)
> +    FAIL_EXIT1 ("response_init called for a query of size %zu",
> +                b->query_length);
> +  if (flags.rcode > 15)
> +    FAIL_EXIT1 ("response_init: invalid RCODE %u", flags.rcode);
> +
> +  /* Copy the transaction ID.  */
> +  b->buffer[0] = b->query_buffer[0];
> +  b->buffer[1] = b->query_buffer[1];
> +
> +  /* Initialize the flags.  */
> +  b->buffer[2] = 0x80;                       /* Mark as response.   */
> +  b->buffer[2] |= b->query_buffer[2] & 0x01; /* Copy the RD bit.  */
> +  if (flags.tc)
> +    b->buffer[2] |= 0x02;
> +  b->buffer[3] = 0x80 | flags.rcode; /* Always set RA.  */
> +
> +  /* Fill in the initial section count values.  */
> +  b->buffer[4] = flags.qdcount >> 8;
> +  b->buffer[5] = flags.qdcount;
> +  b->buffer[6] = flags.ancount >> 8;
> +  b->buffer[7] = flags.ancount;
> +  b->buffer[8] = flags.nscount >> 8;
> +  b->buffer[9] = flags.nscount;
> +  b->buffer[10] = flags.adcount >> 8;
> +  b->buffer[11] = flags.adcount;
> +
> +  b->offset = 12;
> +}
> +
> +void
> +resolv_response_section (struct resolv_response_builder *b, ns_sect section)
> +{
> +  if (b->offset == 0)
> +    FAIL_EXIT1 ("resolv_response_section: response_init not called before");
> +  if (section < b->section)
> +    FAIL_EXIT1 ("resolv_response_section: cannot go back to previous section");
> +  b->section = section;
> +}
> +
> +/* Add a single byte to B.  */
> +static inline void
> +response_add_byte (struct resolv_response_builder *b, unsigned char ch)
> +{
> +  if (b->offset == max_response_length)
> +    FAIL_EXIT1 ("DNS response exceeds 64 KiB limit");
> +  b->buffer[b->offset] = ch;
> +  ++b->offset;
> +}
> +
> +/* Add a 16-bit word VAL to B, in big-endian format.  */
> +static void
> +response_add_16 (struct resolv_response_builder *b, uint16_t val)
> +{
> +  response_add_byte (b, val >> 8);
> +  response_add_byte (b, val);
> +}
> +
> +/* Increment the pers-section record counter in the packet header.  */
> +static void
> +response_count_increment (struct resolv_response_builder *b)
> +{
> +  unsigned int offset = b->section;
> +  offset = 4 + 2 * offset;
> +  ++b->buffer[offset + 1];
> +  if (b->buffer[offset + 1] == 0)
> +    {
> +      /* Carry.  */
> +      ++b->buffer[offset];
> +      if (b->buffer[offset] == 0)
> +        /* Overflow.  */
> +        FAIL_EXIT1 ("too many records in section");
> +    }
> +}
> +
> +void
> +resolv_response_add_question (struct resolv_response_builder *b,
> +                              const char *name, uint16_t class, uint16_t type)
> +{
> +  if (b->offset == 0)
> +    FAIL_EXIT1 ("resolv_response_add_question: "
> +                "resolv_response_init not called");
> +  if (b->section != ns_s_qd)
> +    FAIL_EXIT1 ("resolv_response_add_question: "
> +                "must be called in the question section");
> +
> +  resolv_response_add_name (b, name);
> +  response_add_16 (b, type);
> +  response_add_16 (b, class);
> +
> +  response_count_increment (b);
> +}
> +
> +void
> +resolv_response_add_name (struct resolv_response_builder *b,
> +                          const char *const origname)
> +{
> +  /* Normalized name.  */
> +  char *name;
> +  /* Normalized name with case preserved.  */
> +  char *name_case;
> +  {
> +    size_t namelen = strlen (origname);
> +    /* Remove trailing dots.  FIXME: Handle trailing quoted dots.  */
> +    while (namelen > 0 && origname[namelen - 1] == '.')
> +      --namelen;
> +    name = xmalloc (namelen + 1);
> +    name_case = xmalloc (namelen + 1);
> +    /* Copy and convert to lowercase.  FIXME: This needs to normalize
> +       escaping as well.  */
> +    for (size_t i = 0; i < namelen; ++i)
> +      {
> +        char ch = origname[i];
> +        name_case[i] = ch;
> +        if ('A' <= ch && ch <= 'Z')
> +          ch = ch - 'A' + 'a';
> +        name[i] = ch;
> +      }
> +    name[namelen] = 0;
> +    name_case[namelen] = 0;
> +  }
> +  char *name_start = name;
> +  char *name_case_start = name_case;
> +
> +  bool compression = false;
> +  while (*name)
> +    {
> +      /* Search for a previous name we can reference.  */
> +      ENTRY new_entry =
> +        {
> +          .key = name,
> +          .data = (void *) (uintptr_t) b->offset,
> +        };
> +
> +      /* If the label can be a compression target because it is at a
> +         reachable offset, add it to the hash table.  */
> +      ACTION action;
> +      if (b->offset < (1 << 12))
> +        action = ENTER;
> +      else
> +        action = FIND;
> +
> +      /* Search for known compression offsets in the hash table.  */
> +      ENTRY *e;
> +      if (hsearch_r (new_entry, action, &e, &b->compression_offsets) == 0)
> +        {
> +          if (action == FIND && errno == ESRCH)
> +            /* Fall through.  */
> +            e = NULL;
> +          else
> +            FAIL_EXIT1 ("hsearch_r failure in name compression: %m");
> +        }
> +
> +      /* The name is known.  Reference the previous location.  */
> +      if (e != NULL && e->data != new_entry.data)
> +        {
> +          size_t old_offset = (uintptr_t) e->data;
> +          response_add_byte (b, 0xC0 | (old_offset >> 8));
> +          response_add_byte (b, old_offset);
> +          compression = true;
> +          break;
> +        }
> +
> +      /* The name does not exist yet.  Write one label.  First, add
> +         room for the label length.  */
> +      size_t buffer_label_offset = b->offset;
> +      response_add_byte (b, 0);
> +
> +      /* Copy the label.  */
> +      while (true)
> +        {
> +          char ch = *name_case;
> +          if (ch == '\0')
> +            break;
> +          ++name;
> +          ++name_case;
> +          if (ch == '.')
> +            break;
> +          /* FIXME: Handle escaping.  */
> +          response_add_byte (b, ch);
> +        }
> +
> +      /* Patch in the label length.  */
> +      size_t label_length = b->offset - buffer_label_offset - 1;
> +      if (label_length == 0)
> +        FAIL_EXIT1 ("empty label in name compression: %s", origname);
> +      if (label_length > 63)
> +        FAIL_EXIT1 ("label too long in name compression: %s", origname);
> +      b->buffer[buffer_label_offset] = label_length;
> +
> +      /* Continue with the tail of the name and the next label.  */
> +    }
> +
> +  if (compression)
> +    {
> +      /* If we found an immediate match for the name, we have not put
> +         it into the hash table, and can free it immediately.  */
> +      if (name == name_start)
> +        free (name_start);
> +      else
> +        response_push_pointer_to_free (b, name_start);
> +    }
> +  else
> +    {
> +      /* Terminate the sequence of labels.  With compression, this is
> +         implicit in the compression reference.  */
> +      response_add_byte (b, 0);
> +      response_push_pointer_to_free (b, name_start);
> +    }
> +
> +  free (name_case_start);
> +}
> +
> +void
> +resolv_response_open_record (struct resolv_response_builder *b,
> +                             const char *name,
> +                             uint16_t class, uint16_t type, uint32_t ttl)
> +{
> +  if (b->section == ns_s_qd)
> +    FAIL_EXIT1 ("resolv_response_open_record called in question section");
> +  if (b->current_rdata_offset != 0)
> +    FAIL_EXIT1 ("resolv_response_open_record called with open record");
> +
> +  resolv_response_add_name (b, name);
> +  response_add_16 (b, type);
> +  response_add_16 (b, class);
> +  response_add_16 (b, ttl >> 16);
> +  response_add_16 (b, ttl);
> +
> +  b->current_rdata_offset = b->offset;
> +  /* Add room for the RDATA length.  */
> +  response_add_16 (b, 0);
> +}
> +
> +
> +void
> +resolv_response_close_record (struct resolv_response_builder *b)
> +{
> +  size_t rdata_offset = b->current_rdata_offset;
> +  if (rdata_offset == 0)
> +    FAIL_EXIT1 ("response_close_record called without open record");
> +  size_t rdata_length = b->offset - rdata_offset - 2;
> +  if (rdata_length > 65535)
> +    FAIL_EXIT1 ("RDATA length %zu exceeds limit", rdata_length);
> +  b->buffer[rdata_offset] = rdata_length >> 8;
> +  b->buffer[rdata_offset + 1] = rdata_length;
> +  response_count_increment (b);
> +  b->current_rdata_offset = 0;
> +}
> +
> +void
> +resolv_response_add_data (struct resolv_response_builder *b,
> +                          const void *data, size_t length)
> +{
> +  size_t remaining = max_response_length - b->offset;
> +  if (remaining < length)
> +    FAIL_EXIT1 ("resolv_response_add_data: not enough room for %zu bytes",
> +                length);
> +  memcpy (b->buffer + b->offset, data, length);
> +  b->offset += length;
> +}
> +
> +void
> +resolv_response_drop (struct resolv_response_builder *b)
> +{
> +  b->drop = true;
> +}
> +
> +void
> +resolv_response_close (struct resolv_response_builder *b)
> +{
> +  b->close = true;
> +}
> +
> +void
> +resolv_response_truncate_data (struct resolv_response_builder *b, size_t count)
> +{
> +  if (count > 65535)
> +    FAIL_EXIT1 ("resolv_response_truncate_data: argument too large: %zu",
> +                count);
> +  b->truncate_bytes = count;
> +}
> +
> +
> +size_t
> +resolv_response_length (const struct resolv_response_builder *b)
> +{
> +  return b->offset;
> +}
> +
> +unsigned char *
> +resolv_response_buffer (const struct resolv_response_builder *b)
> +{
> +  unsigned char *result = xmalloc (b->offset);
> +  memcpy (result, b->buffer, b->offset);
> +  return result;
> +}
> +
> +static struct resolv_response_builder *
> +response_builder_allocate
> +  (const unsigned char *query_buffer, size_t query_length)
> +{
> +  struct resolv_response_builder *b = xmalloc (sizeof (*b));
> +  memset (b, 0, offsetof (struct resolv_response_builder, buffer));
> +  b->query_buffer = query_buffer;
> +  b->query_length = query_length;
> +  TEST_VERIFY_EXIT (hcreate_r (10000, &b->compression_offsets) != 0);
> +  return b;
> +}
> +
> +static void
> +response_builder_free (struct resolv_response_builder *b)
> +{
> +  struct to_be_freed *current = b->to_be_freed;
> +  while (current != NULL)
> +    {
> +      struct to_be_freed *next = current->next;
> +      free (current->ptr);
> +      free (current);
> +      current = next;
> +    }
> +  hdestroy_r (&b->compression_offsets);
> +  free (b);
> +}
> +
> +/* DNS query processing. */
> +
> +/* Data extracted from the question section of a DNS packet.  */
> +struct query_info
> +{
> +  char qname[MAXDNAME];
> +  uint16_t qclass;
> +  uint16_t qtype;
> +  struct resolv_edns_info edns;
> +};
> +
> +/* Update *INFO from the specified DNS packet.  */
> +static void
> +parse_query (struct query_info *info,
> +             const unsigned char *buffer, size_t length)
> +{
> +  HEADER hd;
> +  _Static_assert (sizeof (hd) == 12, "DNS header size");
> +  if (length < sizeof (hd))
> +    FAIL_EXIT1 ("malformed DNS query: too short: %zu bytes", length);
> +  memcpy (&hd, buffer, sizeof (hd));
> +
> +  if (ntohs (hd.qdcount) != 1)
> +    FAIL_EXIT1 ("malformed DNS query: wrong question count: %d",
> +                (int) ntohs (hd.qdcount));
> +  if (ntohs (hd.ancount) != 0)
> +    FAIL_EXIT1 ("malformed DNS query: wrong answer count: %d",
> +                (int) ntohs (hd.ancount));
> +  if (ntohs (hd.nscount) != 0)
> +    FAIL_EXIT1 ("malformed DNS query: wrong authority count: %d",
> +                (int) ntohs (hd.nscount));
> +  if (ntohs (hd.arcount) > 1)
> +    FAIL_EXIT1 ("malformed DNS query: wrong additional count: %d",
> +                (int) ntohs (hd.arcount));
> +
> +  int ret = dn_expand (buffer, buffer + length, buffer + sizeof (hd),
> +                       info->qname, sizeof (info->qname));
> +  if (ret < 0)
> +    FAIL_EXIT1 ("malformed DNS query: cannot uncompress QNAME");
> +
> +  /* Obtain QTYPE and QCLASS.  */
> +  size_t remaining = length - (12 + ret);
> +  struct
> +  {
> +    uint16_t qtype;
> +    uint16_t qclass;
> +  } qtype_qclass;
> +  if (remaining < sizeof (qtype_qclass))
> +    FAIL_EXIT1 ("malformed DNS query: "
> +                "query lacks QCLASS/QTYPE, QNAME: %s", info->qname);
> +  memcpy (&qtype_qclass, buffer + 12 + ret, sizeof (qtype_qclass));
> +  info->qclass = ntohs (qtype_qclass.qclass);
> +  info->qtype = ntohs (qtype_qclass.qtype);
> +
> +  memset (&info->edns, 0, sizeof (info->edns));
> +  if (ntohs (hd.arcount) > 0)
> +    {
> +      /* Parse EDNS record.  */
> +      struct __attribute__ ((packed, aligned (1)))
> +      {
> +        uint8_t root;
> +        uint16_t rtype;
> +        uint16_t payload;
> +        uint8_t edns_extended_rcode;
> +        uint8_t edns_version;
> +        uint16_t flags;
> +        uint16_t rdatalen;
> +      } rr;
> +      _Static_assert (sizeof (rr) == 11, "EDNS record size");
> +
> +      if (remaining < 4 + sizeof (rr))
> +        FAIL_EXIT1 ("mailformed DNS query: no room for EDNS record");
> +      memcpy (&rr, buffer + 12 + ret + 4, sizeof (rr));
> +      if (rr.root != 0)
> +        FAIL_EXIT1 ("malformed DNS query: invalid OPT RNAME: %d\n", rr.root);
> +      if (rr.rtype != htons (41))
> +        FAIL_EXIT1 ("malformed DNS query: invalid OPT type: %d\n",
> +                    ntohs (rr.rtype));
> +      info->edns.active = true;
> +      info->edns.extended_rcode = rr.edns_extended_rcode;
> +      info->edns.version = rr.edns_version;
> +      info->edns.flags = ntohs (rr.flags);
> +      info->edns.payload_size = ntohs (rr.payload);
> +    }
> +}
> +
> +
> +/* Main testing framework.  */
> +
> +/* Per-server information.  One struct is allocated for each test
> +   server.  */
> +struct resolv_test_server
> +{
> +  /* Local address of the server.  UDP and TCP use the same port.  */
> +  struct sockaddr_in address;
> +
> +  /* File descriptor of the UDP server, or -1 if this server is
> +     disabled.  */
> +  int socket_udp;
> +
> +  /* File descriptor of the TCP server, or -1 if this server is
> +     disabled.  */
> +  int socket_tcp;
> +
> +  /* Counter of the number of responses processed so far.  */
> +  size_t response_number;
> +
> +  /* Thread handles for the server threads (if not disabled in the
> +     configuration).  */
> +  pthread_t thread_udp;
> +  pthread_t thread_tcp;
> +};
> +
> +/* Main struct for keeping track of libresolv redirection and
> +   testing.  */
> +struct resolv_test
> +{
> +  /* After initialization, any access to the struct must be performed
> +     while this lock is acquired.  */
> +  pthread_mutex_t lock;
> +
> +  /* Data for each test server. */
> +  struct resolv_test_server servers[resolv_max_test_servers];
> +
> +  /* Used if config.single_thread_udp is true.  */
> +  pthread_t thread_udp_single;
> +
> +  struct resolv_redirect_config config;
> +  bool termination_requested;
> +};
> +
> +/* Function implementing a server thread.  */
> +typedef void (*thread_callback) (struct resolv_test *, int server_index);
> +
> +/* Storage for thread-specific data, for passing to the
> +   thread_callback function.  */
> +struct thread_closure
> +{
> +  struct resolv_test *obj;      /* Current test object.  */
> +  thread_callback callback;     /* Function to call.  */
> +  int server_index;             /* Index of the implemented server.  */
> +};
> +
> +/* Wrap response_callback as a function which can be passed to
> +   pthread_create.  */
> +static void *
> +thread_callback_wrapper (void *arg)
> +{
> +  struct thread_closure *closure = arg;
> +  closure->callback (closure->obj, closure->server_index);
> +  free (closure);
> +  return NULL;
> +}
> +
> +/* Start a server thread for the specified SERVER_INDEX, implemented
> +   by CALLBACK.  */
> +static pthread_t
> +start_server_thread (struct resolv_test *obj, int server_index,
> +                     thread_callback callback)
> +{
> +  struct thread_closure *closure = xmalloc (sizeof (*closure));
> +  *closure = (struct thread_closure)
> +    {
> +      .obj = obj,
> +      .callback = callback,
> +      .server_index = server_index,
> +    };
> +  return xpthread_create (NULL, thread_callback_wrapper, closure);
> +}
> +
> +/* Process one UDP query.  Return false if a termination requested has
> +   been detected.  */
> +static bool
> +server_thread_udp_process_one (struct resolv_test *obj, int server_index)
> +{
> +  unsigned char query[512];
> +  struct sockaddr_storage peer;
> +  socklen_t peerlen = sizeof (peer);
> +  size_t length = xrecvfrom (obj->servers[server_index].socket_udp,
> +                             query, sizeof (query), 0,
> +                             (struct sockaddr *) &peer, &peerlen);
> +  /* Check for termination.  */
> +  {
> +    bool termination_requested;
> +    xpthread_mutex_lock (&obj->lock);
> +    termination_requested = obj->termination_requested;
> +    xpthread_mutex_unlock (&obj->lock);
> +    if (termination_requested)
> +      return false;
> +  }
> +
> +
> +  struct query_info qinfo;
> +  parse_query (&qinfo, query, length);
> +  if (test_verbose > 0)
> +    {
> +      if (test_verbose > 1)
> +        printf ("info: UDP server %d: incoming query:"
> +                " %zd bytes, %s/%u/%u, tnxid=0x%02x%02x\n",
> +                server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype,
> +                query[0], query[1]);
> +      else
> +        printf ("info: UDP server %d: incoming query:"
> +                " %zd bytes, %s/%u/%u\n",
> +                server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype);
> +    }
> +
> +  struct resolv_response_context ctx =
> +    {
> +      .query_buffer = query,
> +      .query_length = length,
> +      .server_index = server_index,
> +      .tcp = false,
> +      .edns = qinfo.edns,
> +    };
> +  struct resolv_response_builder *b = response_builder_allocate (query, length);
> +  obj->config.response_callback
> +    (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype);
> +
> +  if (b->drop)
> +    {
> +      if (test_verbose)
> +        printf ("info: UDP server %d: dropping response to %s/%u/%u\n",
> +                server_index, qinfo.qname, qinfo.qclass, qinfo.qtype);
> +    }
> +  else
> +    {
> +      if (test_verbose)
> +        {
> +          if (b->offset >= 12)
> +            printf ("info: UDP server %d: sending response:"
> +                    " %zu bytes, RCODE %d (for %s/%u/%u)\n",
> +                    server_index, b->offset, b->buffer[3] & 0x0f,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype);
> +          else
> +            printf ("info: UDP server %d: sending response: %zu bytes"
> +                    " (for %s/%u/%u)\n",
> +                    server_index, b->offset,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype);
> +          if (b->truncate_bytes > 0)
> +            printf ("info:    truncated by %u bytes\n", b->truncate_bytes);
> +        }
> +      size_t to_send = b->offset;
> +      if (to_send < b->truncate_bytes)
> +        to_send = 0;
> +      else
> +        to_send -= b->truncate_bytes;
> +
> +      /* Ignore most errors here because the other end may have closed
> +         the socket. */
> +      if (sendto (obj->servers[server_index].socket_udp,
> +                  b->buffer, to_send, 0,
> +                  (struct sockaddr *) &peer, peerlen) < 0)
> +        TEST_VERIFY_EXIT (errno != EBADF);
> +    }
> +  response_builder_free (b);
> +  return true;
> +}
> +
> +/* UDP thread_callback function.  Variant for one thread per
> +   server.  */
> +static void
> +server_thread_udp (struct resolv_test *obj, int server_index)
> +{
> +  while (server_thread_udp_process_one (obj, server_index))
> +    ;
> +}
> +
> +/* Single-threaded UDP processing function, for the single_thread_udp
> +   case.  */
> +static void *
> +server_thread_udp_single (void *closure)
> +{
> +  struct resolv_test *obj = closure;
> +
> +  struct pollfd fds[resolv_max_test_servers];
> +  for (int server_index = 0; server_index < resolv_max_test_servers;
> +       ++server_index)
> +    if (obj->config.servers[server_index].disable_udp)
> +      fds[server_index] = (struct pollfd) {.fd = -1};
> +    else
> +      {
> +        fds[server_index] = (struct pollfd)
> +          {
> +            .fd = obj->servers[server_index].socket_udp,
> +            .events = POLLIN
> +          };
> +
> +        /* Make the socket non-blocking.  */
> +        int flags = fcntl (obj->servers[server_index].socket_udp, F_GETFL, 0);
> +        if (flags < 0)
> +          FAIL_EXIT1 ("fcntl (F_GETFL): %m");
> +        flags |= O_NONBLOCK;
> +        if (fcntl (obj->servers[server_index].socket_udp, F_SETFL, flags) < 0)
> +          FAIL_EXIT1 ("fcntl (F_SETFL): %m");
> +      }
> +
> +  while (true)
> +    {
> +      xpoll (fds, resolv_max_test_servers, -1);
> +      for (int server_index = 0; server_index < resolv_max_test_servers;
> +           ++server_index)
> +        if (fds[server_index].revents != 0)
> +          {
> +            if (!server_thread_udp_process_one (obj, server_index))
> +              goto out;
> +            fds[server_index].revents = 0;
> +          }
> +    }
> +
> + out:
> +  return NULL;
> +}
> +
> +/* Start the single UDP handler thread (for the single_thread_udp
> +   case).  */
> +static void
> +start_server_thread_udp_single (struct resolv_test *obj)
> +{
> +  obj->thread_udp_single
> +    = xpthread_create (NULL, server_thread_udp_single, obj);
> +}
> +
> +/* Data describing a TCP client connect.  */
> +struct tcp_thread_closure
> +{
> +  struct resolv_test *obj;
> +  int server_index;
> +  int client_socket;
> +};
> +
> +/* Read a complete DNS query packet.  If EOF_OK, an immediate
> +   end-of-file condition is acceptable.  */
> +static bool
> +read_fully (int fd, void *buf, size_t len, bool eof_ok)
> +{
> +  const void *const end = buf + len;
> +  while (buf < end)
> +    {
> +      ssize_t ret = read (fd, buf, end - buf);
> +      if (ret == 0)
> +        {
> +          if (!eof_ok)
> +            {
> +              support_record_failure ();
> +              printf ("error: unexpected EOF on TCP connection\n");
> +            }
> +          return false;
> +        }
> +      else if (ret < 0)
> +        {
> +          if (!eof_ok || errno != ECONNRESET)
> +            {
> +              support_record_failure ();
> +              printf ("error: TCP read: %m\n");
> +            }
> +          return false;
> +        }
> +      buf += ret;
> +      eof_ok = false;
> +    }
> +  return true;
> +}
> +
> +/* Write an array of iovecs.  Terminate the process on failure.  */
> +static void
> +writev_fully (int fd, struct iovec *buffers, size_t count)
> +{
> +  while (count > 0)
> +    {
> +      /* Skip zero-length write requests.  */
> +      if (buffers->iov_len == 0)
> +        {
> +          ++buffers;
> +          --count;
> +          continue;
> +        }
> +      /* Try to rewrite the remaing buffers.  */
> +      ssize_t ret = writev (fd, buffers, count);
> +      if (ret < 0)
> +        FAIL_EXIT1 ("writev: %m");
> +      if (ret == 0)
> +        FAIL_EXIT1 ("writev: invalid return value zero");
> +      /* Find the buffers that were successfully written.  */
> +      while (ret > 0)
> +        {
> +          if (count == 0)
> +            FAIL_EXIT1 ("internal writev consistency failure");
> +          /* Current buffer was partially written.  */
> +          if (buffers->iov_len > (size_t) ret)
> +            {
> +              buffers->iov_base += ret;
> +              buffers->iov_len -= ret;
> +              ret = 0;
> +            }
> +          else
> +            {
> +              ret -= buffers->iov_len;
> +              buffers->iov_len = 0;
> +              ++buffers;
> +              --count;
> +            }
> +        }
> +    }
> +}
> +
> +/* Thread callback for handling a single established TCP connection to
> +   a client.  */
> +static void *
> +server_thread_tcp_client (void *arg)
> +{
> +  struct tcp_thread_closure *closure = arg;
> +
> +  while (true)
> +    {
> +      /* Read packet length.  */
> +      uint16_t query_length;
> +      if (!read_fully (closure->client_socket,
> +                       &query_length, sizeof (query_length), true))
> +        break;
> +      query_length = ntohs (query_length);
> +
> +      /* Read the packet.  */
> +      unsigned char *query_buffer = xmalloc (query_length);
> +      read_fully (closure->client_socket, query_buffer, query_length, false);
> +
> +      struct query_info qinfo;
> +      parse_query (&qinfo, query_buffer, query_length);
> +      if (test_verbose > 0)
> +        {
> +          if (test_verbose > 1)
> +            printf ("info: UDP server %d: incoming query:"
> +                    " %d bytes, %s/%u/%u, tnxid=0x%02x%02x\n",
> +                    closure->server_index, query_length,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype,
> +                    query_buffer[0], query_buffer[1]);
> +          else
> +            printf ("info: TCP server %d: incoming query:"
> +                    " %u bytes, %s/%u/%u\n",
> +                    closure->server_index, query_length,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype);
> +        }
> +
> +      struct resolv_response_context ctx =
> +        {
> +          .query_buffer = query_buffer,
> +          .query_length = query_length,
> +          .server_index = closure->server_index,
> +          .tcp = true,
> +          .edns = qinfo.edns,
> +        };
> +      struct resolv_response_builder *b = response_builder_allocate
> +        (query_buffer, query_length);
> +      closure->obj->config.response_callback
> +        (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype);
> +
> +      if (b->drop)
> +        {
> +          if (test_verbose)
> +            printf ("info: TCP server %d: dropping response to %s/%u/%u\n",
> +                    closure->server_index,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype);
> +        }
> +      else
> +        {
> +          if (test_verbose)
> +            printf ("info: TCP server %d: sending response: %zu bytes"
> +                    " (for %s/%u/%u)\n",
> +                    closure->server_index, b->offset,
> +                    qinfo.qname, qinfo.qclass, qinfo.qtype);
> +          uint16_t length = htons (b->offset);
> +          size_t to_send = b->offset;
> +          if (to_send < b->truncate_bytes)
> +            to_send = 0;
> +          else
> +            to_send -= b->truncate_bytes;
> +          struct iovec buffers[2] =
> +            {
> +              {&length, sizeof (length)},
> +              {b->buffer, to_send}
> +            };
> +          writev_fully (closure->client_socket, buffers, 2);
> +        }
> +      bool close_flag = b->close;
> +      response_builder_free (b);
> +      free (query_buffer);
> +      if (close_flag)
> +        break;
> +    }
> +
> +  xclose (closure->client_socket);
> +  free (closure);
> +  return NULL;
> +}
> +
> +/* thread_callback for the TCP case.  Accept connections and create a
> +   new thread for each client.  */
> +static void
> +server_thread_tcp (struct resolv_test *obj, int server_index)
> +{
> +  while (true)
> +    {
> +      /* Get the client conenction.  */
> +      int client_socket = xaccept
> +        (obj->servers[server_index].socket_tcp, NULL, NULL);
> +
> +      /* Check for termination.  */
> +      xpthread_mutex_lock (&obj->lock);
> +      if (obj->termination_requested)
> +        {
> +          xpthread_mutex_unlock (&obj->lock);
> +          xclose (client_socket);
> +          break;
> +        }
> +      xpthread_mutex_unlock (&obj->lock);
> +
> +      /* Spawn a new thread for handling this connection.  */
> +      struct tcp_thread_closure *closure = xmalloc (sizeof (*closure));
> +      *closure = (struct tcp_thread_closure)
> +        {
> +          .obj = obj,
> +          .server_index = server_index,
> +          .client_socket = client_socket,
> +        };
> +
> +      pthread_t thr
> +        = xpthread_create (NULL, server_thread_tcp_client, closure);
> +      /* TODO: We should keep track of this thread so that we can
> +         block in resolv_test_end until it has exited.  */
> +      xpthread_detach (thr);
> +    }
> +}
> +
> +/* Create UDP and TCP server sockets.  */
> +static void
> +make_server_sockets (struct resolv_test_server *server)
> +{
> +  while (true)
> +    {
> +      server->socket_udp = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
> +      server->socket_tcp = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
> +
> +      /* Pick the address for the UDP socket.  */
> +      server->address = (struct sockaddr_in)
> +        {
> +          .sin_family = AF_INET,
> +          .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK)}
> +        };
> +      xbind (server->socket_udp,
> +             (struct sockaddr *)&server->address, sizeof (server->address));
> +
> +      /* Retrieve the address. */
> +      socklen_t addrlen = sizeof (server->address);
> +      xgetsockname (server->socket_udp,
> +                    (struct sockaddr *)&server->address, &addrlen);
> +
> +      /* Bind the TCP socket to the same address.  */
> +      {
> +        int on = 1;
> +        xsetsockopt (server->socket_tcp, SOL_SOCKET, SO_REUSEADDR,
> +                     &on, sizeof (on));
> +      }
> +      if (bind (server->socket_tcp,
> +                (struct sockaddr *)&server->address,
> +                sizeof (server->address)) != 0)
> +        {
> +          /* Port collision.  The UDP bind succeeded, but the TCP BIND
> +             failed.  We assume here that the kernel will pick the
> +             next local UDP address randomly.  */
> +          if (errno == EADDRINUSE)
> +            {
> +              xclose (server->socket_udp);
> +              xclose (server->socket_tcp);
> +              continue;
> +            }
> +          FAIL_EXIT1 ("TCP bind: %m");
> +        }
> +      xlisten (server->socket_tcp, 5);
> +      break;
> +    }
> +}
> +
> +/* One-time initialization of NSS.  */
> +static void
> +resolv_redirect_once (void)
> +{
> +  /* Only use nss_dns.  */
> +  __nss_configure_lookup ("hosts", "dns");
> +  __nss_configure_lookup ("networks", "dns");
> +  /* Enter a network namespace for isolation and firewall state
> +     cleanup.  The tests will still work if these steps fail, but they
> +     may be less reliable.  */
> +  support_become_root ();
> +  support_enter_network_namespace ();
> +}
> +pthread_once_t resolv_redirect_once_var = PTHREAD_ONCE_INIT;
> +
> +void
> +resolv_test_init (void)
> +{
> +  /* Perform one-time initialization of NSS.  */
> +  xpthread_once (&resolv_redirect_once_var, resolv_redirect_once);
> +}
> +
> +/* Copy the search path from CONFIG.search to the _res object.  */
> +static void
> +set_search_path (struct resolv_redirect_config config)
> +{
> +  memset (_res.defdname, 0, sizeof (_res.defdname));
> +  memset (_res.dnsrch, 0, sizeof (_res.dnsrch));
> +
> +  char *current = _res.defdname;
> +  char *end = current + sizeof (_res.defdname);
> +
> +  for (unsigned int i = 0;
> +       i < sizeof (config.search) / sizeof (config.search[0]); ++i)
> +    {
> +      if (config.search[i] == NULL)
> +        continue;
> +
> +      size_t length = strlen (config.search[i]) + 1;
> +      size_t remaining = end - current;
> +      TEST_VERIFY_EXIT (length <= remaining);
> +      memcpy (current, config.search[i], length);
> +      _res.dnsrch[i] = current;
> +      current += length;
> +    }
> +}
> +
> +struct resolv_test *
> +resolv_test_start (struct resolv_redirect_config config)
> +{
> +  /* Apply configuration defaults.  */
> +  if (config.nscount == 0)
> +    config.nscount = resolv_max_test_servers;
> +
> +  struct resolv_test *obj = xmalloc (sizeof (*obj));
> +  *obj = (struct resolv_test) {
> +    .config = config,
> +    .lock = PTHREAD_MUTEX_INITIALIZER,
> +  };
> +
> +  resolv_test_init ();
> +
> +  /* Create all the servers, to reserve the necessary ports.  */
> +  for (int server_index = 0; server_index < config.nscount; ++server_index)
> +    make_server_sockets (obj->servers + server_index);
> +
> +  /* Start server threads.  Disable the server ports, as
> +     requested.  */
> +  for (int server_index = 0; server_index < config.nscount; ++server_index)
> +    {
> +      struct resolv_test_server *server = obj->servers + server_index;
> +      if (config.servers[server_index].disable_udp)
> +        {
> +          xclose (server->socket_udp);
> +          server->socket_udp = -1;
> +        }
> +      else if (!config.single_thread_udp)
> +        server->thread_udp = start_server_thread (obj, server_index,
> +                                                  server_thread_udp);
> +      if (config.servers[server_index].disable_tcp)
> +        {
> +          xclose (server->socket_tcp);
> +          server->socket_tcp = -1;
> +        }
> +      else
> +        server->thread_tcp = start_server_thread (obj, server_index,
> +                                                  server_thread_tcp);
> +    }
> +  if (config.single_thread_udp)
> +    start_server_thread_udp_single (obj);
> +
> +  int timeout = 1;
> +
> +  /* Initialize libresolv.  */
> +  TEST_VERIFY_EXIT (res_init () == 0);
> +
> +  /* Disable IPv6 name server addresses.  The code below only
> +     overrides the IPv4 addresses.  */
> +  __res_iclose (&_res, true);
> +  _res._u._ext.nscount = 0;
> +
> +  /* Redirect queries to the server socket.  */
> +  if (test_verbose)
> +    {
> +      printf ("info: old timeout value: %d\n", _res.retrans);
> +      printf ("info: old retry attempt value: %d\n", _res.retry);
> +      printf ("info: old _res.options: 0x%lx\n", _res.options);
> +      printf ("info: old _res.nscount value: %d\n", _res.nscount);
> +      printf ("info: old _res.ndots value: %d\n", _res.ndots);
> +    }
> +  _res.retrans = timeout;
> +  _res.retry = 4;
> +  _res.nscount = config.nscount;
> +  _res.options = RES_INIT | RES_RECURSE | RES_DEFNAMES | RES_DNSRCH;
> +  _res.ndots = 1;
> +  if (test_verbose)
> +    {
> +      printf ("info: new timeout value: %d\n", _res.retrans);
> +      printf ("info: new retry attempt value: %d\n", _res.retry);
> +      printf ("info: new _res.options: 0x%lx\n", _res.options);
> +      printf ("info: new _res.nscount value: %d\n", _res.nscount);
> +      printf ("info: new _res.ndots value: %d\n", _res.ndots);
> +    }
> +  for (int server_index = 0; server_index < config.nscount; ++server_index)
> +    {
> +      _res.nsaddr_list[server_index] = obj->servers[server_index].address;
> +      if (test_verbose)
> +        {
> +          char buf[256];
> +          TEST_VERIFY_EXIT
> +            (inet_ntop (AF_INET, &obj->servers[server_index].address.sin_addr,
> +                        buf, sizeof (buf)) != NULL);
> +          printf ("info: server %d: %s/%u\n",
> +                  server_index, buf,
> +                  htons (obj->servers[server_index].address.sin_port));
> +        }
> +    }
> +
> +  set_search_path (config);
> +
> +  return obj;
> +}
> +
> +void
> +resolv_test_end (struct resolv_test *obj)
> +{
> +  res_close ();
> +
> +  xpthread_mutex_lock (&obj->lock);
> +  obj->termination_requested = true;
> +  xpthread_mutex_unlock (&obj->lock);
> +
> +  /* Send trigger packets to unblock the server threads.  */
> +  for (int server_index = 0; server_index < obj->config.nscount;
> +       ++server_index)
> +    {
> +      if (!obj->config.servers[server_index].disable_udp)
> +        {
> +          int sock = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
> +          xsendto (sock, "", 1, 0,
> +                   (struct sockaddr *) &obj->servers[server_index].address,
> +                   sizeof (obj->servers[server_index].address));
> +          xclose (sock);
> +        }
> +      if (!obj->config.servers[server_index].disable_tcp)
> +        {
> +          int sock = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
> +          xconnect (sock,
> +                    (struct sockaddr *) &obj->servers[server_index].address,
> +                    sizeof (obj->servers[server_index].address));
> +          xclose (sock);
> +        }
> +    }
> +
> +  if (obj->config.single_thread_udp)
> +    xpthread_join (obj->thread_udp_single);
> +
> +  /* Wait for the server threads to terminate.  */
> +  for (int server_index = 0; server_index < obj->config.nscount;
> +       ++server_index)
> +    {
> +      if (!obj->config.servers[server_index].disable_udp)
> +        {
> +          if (!obj->config.single_thread_udp)
> +            xpthread_join (obj->servers[server_index].thread_udp);
> +          xclose (obj->servers[server_index].socket_udp);
> +        }
> +      if (!obj->config.servers[server_index].disable_tcp)
> +        {
> +          xpthread_join (obj->servers[server_index].thread_tcp);
> +          xclose (obj->servers[server_index].socket_tcp);
> +        }
> +    }
> +
> +  free (obj);
> +}
> diff --git a/support/resolv_test.h b/support/resolv_test.h
> new file mode 100644
> index 0000000..6498751
> --- /dev/null
> +++ b/support/resolv_test.h
> @@ -0,0 +1,180 @@
> +/* DNS test framework and libresolv redirection.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_RESOLV_TEST_H
> +#define SUPPORT_RESOLV_TEST_H
> +
> +#include <arpa/nameser.h>
> +#include <stdbool.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Information about EDNS properties of a DNS query.  */
> +struct resolv_edns_info
> +{
> +  bool active;
> +  uint8_t extended_rcode;
> +  uint8_t version;
> +  uint16_t flags;
> +  uint16_t payload_size;
> +};
> +
> +/* This struct provides context information when the response callback
> +   specified in struct resolv_redirect_config is invoked. */
> +struct resolv_response_context
> +{
> +  const unsigned char *query_buffer;
> +  size_t query_length;
> +  int server_index;
> +  bool tcp;
> +  struct resolv_edns_info edns;
> +};
> +
> +/* This opaque struct is used to construct responses from within the
> +   response callback function.  */
> +struct resolv_response_builder;
> +
> +/* This opaque struct collects information about the resolver testing
> +   currently in progress.  */
> +struct resolv_test;
> +
> +enum
> +  {
> +    /* Maximum number of test servers supported by the framework.  */
> +    resolv_max_test_servers = 3,
> +  };
> +
> +/* Configuration settings specific to individual test servers.  */
> +struct resolv_redirect_server_config
> +{
> +  bool disable_tcp;             /* If true, no TCP server is listening.  */
> +  bool disable_udp;             /* If true, no UDP server is listening.  */
> +};
> +
> +/* Instructions for setting up the libresolv redirection.  */
> +struct resolv_redirect_config
> +{
> +  /* The response_callback function is called for every incoming DNS
> +     packet, over UDP or TCP.  It must be specified, the other
> +     configuration settings are optional.  */
> +  void (*response_callback) (const struct resolv_response_context *,
> +                             struct resolv_response_builder *,
> +                             const char *qname,
> +                             uint16_t qclass, uint16_t qtype);
> +
> +  /* Per-server configuration.  */
> +  struct resolv_redirect_server_config servers[resolv_max_test_servers];
> +
> +  /* Search path entries.  The first entry serves as the default
> +     domain name as well.  */
> +  const char *search[7];
> +
> +  /* Number of servers to activate in resolv.  0 means the default,
> +     resolv_max_test_servers.  */
> +  int nscount;
> +
> +  /* If true, use a single thread to process all UDP queries.  This
> +     may results in more predictable ordering of queries and
> +     responses.  */
> +  bool single_thread_udp;
> +};
> +
> +/* Configure NSS to use, nss_dns only for aplicable databases, and try
> +   to put the process into a network namespace for better isolation.
> +   This may have to be called before resolv_test_start, before the
> +   process creates any threads.  Otherwise, initialization is
> +   performed by resolv_test_start implicitly.  */
> +void resolv_test_init (void);
> +
> +/* Initiate resolver testing.  This updates the _res variable as
> +   needed.  As a side effect, NSS is reconfigured to use nss_dns only
> +   for aplicable databases, and the process may enter a network
> +   namespace for better isolation.  */
> +struct resolv_test *resolv_test_start (struct resolv_redirect_config);
> +
> +/* Call this function at the end of resolver testing, to free
> +   resources and report pending errors (if any).  */
> +void resolv_test_end (struct resolv_test *);
> +
> +/* The remaining facilities in this file are used for constructing
> +   response packets from the response_callback function.  */
> +
> +/* Special settings for constructing responses from the callback.  */
> +struct resolv_response_flags
> +{
> +  /* 4-bit response code to incorporate into the response. */
> +  unsigned char rcode;
> +
> +  /* If true, the TC (truncation) flag will be set.  */
> +  bool tc;
> +
> +  /* Initial section count values.  Can be used to artificially
> +     increase the counts, for malformed packet testing.*/
> +  unsigned short qdcount;
> +  unsigned short ancount;
> +  unsigned short nscount;
> +  unsigned short adcount;
> +};
> +
> +/* Begin a new response with the requested flags.  Must be called
> +   first.  */
> +void resolv_response_init (struct resolv_response_builder *,
> +                           struct resolv_response_flags);
> +
> +/* Switches to the section in the response packet.  Only forward
> +   movement is supported.  */
> +void resolv_response_section (struct resolv_response_builder *, ns_sect);
> +
> +/* Add a question record to the question section.  */
> +void resolv_response_add_question (struct resolv_response_builder *,
> +                                   const char *name, uint16_t class,
> +                                   uint16_t type);
> +/* Starts a new resource record with the specified owner name, class,
> +   type, and TTL.  Data is supplied with resolv_response_add_data or
> +   resolv_response_add_name.  */
> +void resolv_response_open_record (struct resolv_response_builder *,
> +                                  const char *name, uint16_t class,
> +                                  uint16_t type, uint32_t ttl);
> +
> +/* Add unstructed bytes to the RDATA part of a resource record.  */
> +void resolv_response_add_data (struct resolv_response_builder *,
> +                               const void *, size_t);
> +
> +/* Add a compressed domain name to the RDATA part of a resource
> +   record.  */
> +void resolv_response_add_name (struct resolv_response_builder *,
> +                               const char *name);
> +
> +/* Mark the end of the constructed record.  Must be called last.  */
> +void resolv_response_close_record (struct resolv_response_builder *);
> +
> +/* Drop this query packet (that is, do not send a response, not even
> +   an empty packet).  */
> +void resolv_response_drop (struct resolv_response_builder *);
> +
> +/* In TCP mode, close the connection after this packet (if a response
> +   is sent).  */
> +void resolv_response_close (struct resolv_response_builder *);
> +
> +/* The size of the response packet built so far.  */
> +size_t resolv_response_length (const struct resolv_response_builder *);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_RESOLV_TEST_H */
> diff --git a/support/run_diff.h b/support/run_diff.h
> new file mode 100644
> index 0000000..f65b5dd
> --- /dev/null
> +++ b/support/run_diff.h
> @@ -0,0 +1,31 @@
> +/* Invoke the system diff tool to compare two strings.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_RUN_DIFF_H
> +#define SUPPORT_RUN_DIFF_H
> +
> +/* Compare the two NUL-terminated strings LEFT and RIGHT using the
> +   diff tool.  Label the sides of the diff with LEFT_LABEL and
> +   RIGHT_LABEL, respectively.
> +
> +   This function assumes that LEFT and RIGHT are different
> +   strings.  */
> +void support_run_diff (const char *left_label, const char *left,
> +                       const char *right_label, const char *right);
> +
> +#endif /* SUPPORT_RUN_DIFF_H */
> diff --git a/support/set_fortify_handler.c b/support/set_fortify_handler.c
> new file mode 100644
> index 0000000..f434a80
> --- /dev/null
> +++ b/support/set_fortify_handler.c
> @@ -0,0 +1,34 @@
> +/* Set signal handler for use in fortify tests.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <signal.h>
> +
> +void
> +set_fortify_handler (void (*handler) (int sig))
> +{
> +  struct sigaction sa;
> +
> +  sa.sa_handler = handler;
> +  sa.sa_flags = 0;
> +  sigemptyset (&sa.sa_mask);
> +
> +  sigaction (SIGABRT, &sa, NULL);
> +  ignore_stderr ();
> +}
> diff --git a/support/support-xstat.c b/support/support-xstat.c
> new file mode 100644
> index 0000000..86a81ec
> --- /dev/null
> +++ b/support/support-xstat.c
> @@ -0,0 +1,30 @@
> +/* stat64 with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* NB: Non-standard file name to avoid sysdeps override for xstat.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/stat.h>
> +
> +void
> +xstat (const char *path, struct stat64 *result)
> +{
> +  if (stat64 (path, result) != 0)
> +    FAIL_EXIT1 ("stat64 (\"%s\"): %m", path);
> +}
> diff --git a/support/support.h b/support/support.h
> new file mode 100644
> index 0000000..4b5f04c
> --- /dev/null
> +++ b/support/support.h
> @@ -0,0 +1,74 @@
> +/* Common extra functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* This header file should only contain definitions compatible with
> +   C90.  (Using __attribute__ is fine because <features.h> provides a
> +   fallback.)  */
> +
> +#ifndef SUPPORT_H
> +#define SUPPORT_H
> +
> +#include <stddef.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Write a message to standard output.  Can be used in signal
> +   handlers.  */
> +void write_message (const char *message) __attribute__ ((nonnull (1)));
> +
> +/* Avoid all the buffer overflow messages on stderr.  */
> +void ignore_stderr (void);
> +
> +/* Set fortification error handler.  Used when tests want to verify that bad
> +   code is caught by the library.  */
> +void set_fortify_handler (void (*handler) (int sig));
> +
> +/* Report an out-of-memory error for the allocation of SIZE bytes in
> +   FUNCTION, terminating the process.  */
> +void oom_error (const char *function, size_t size)
> +  __attribute__ ((nonnull (1)));
> +
> +/* Return a pointer to a memory region of SIZE bytes.  The memory is
> +   initialized to zero and will be shared with subprocesses (across
> +   fork).  The returned pointer must be freed using
> +   support_shared_free; it is not compatible with the malloc
> +   functions.  */
> +void *support_shared_allocate (size_t size);
> +
> +/* Deallocate a pointer returned by support_shared_allocate.  */
> +void support_shared_free (void *);
> +
> +/* Write CONTENTS to the file PATH.  Create or truncate the file as
> +   needed.  The file mode is 0666 masked by the umask.  Terminate the
> +   process on error.  */
> +void support_write_file_string (const char *path, const char *contents);
> +
> +/* Error-checking wrapper functions which terminate the process on
> +   error.  */
> +
> +void *xmalloc (size_t) __attribute__ ((malloc));
> +void *xcalloc (size_t n, size_t s) __attribute__ ((malloc));
> +void *xrealloc (void *p, size_t n);
> +char *xasprintf (const char *format, ...)
> +  __attribute__ ((format (printf, 1, 2), malloc));
> +char *xstrdup (const char *);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_H */
> diff --git a/support/support_become_root.c b/support/support_become_root.c
> new file mode 100644
> index 0000000..3fa0bd4
> --- /dev/null
> +++ b/support/support_become_root.c
> @@ -0,0 +1,40 @@
> +/* Acquire root privileges.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/namespace.h>
> +
> +#include <sched.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +
> +bool
> +support_become_root (void)
> +{
> +#ifdef CLONE_NEWUSER
> +  if (unshare (CLONE_NEWUSER | CLONE_NEWNS) == 0)
> +    /* Even if we do not have UID zero, we have extended privileges at
> +       this point.  */
> +    return true;
> +#endif
> +  if (setuid (0) != 0)
> +    {
> +      printf ("warning: could not become root outside namespace (%m)\n");
> +      return false;
> +    }
> +  return true;
> +}
> diff --git a/support/support_can_chroot.c b/support/support_can_chroot.c
> new file mode 100644
> index 0000000..0dfd2de
> --- /dev/null
> +++ b/support/support_can_chroot.c
> @@ -0,0 +1,65 @@
> +/* Return true if the process can perform a chroot operation.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <stdio.h>
> +#include <support/check.h>
> +#include <support/namespace.h>
> +#include <support/support.h>
> +#include <sys/stat.h>
> +#include <unistd.h>
> +#include <xunistd.h>
> +
> +static void
> +callback (void *closure)
> +{
> +  int *result = closure;
> +  struct stat64 before;
> +  xstat ("/dev", &before);
> +  if (chroot ("/dev") != 0)
> +    {
> +      *result = errno;
> +      return;
> +    }
> +  struct stat64 after;
> +  xstat ("/", &after);
> +  TEST_VERIFY (before.st_dev == after.st_dev);
> +  TEST_VERIFY (before.st_ino == after.st_ino);
> +  *result = 0;
> +}
> +
> +bool
> +support_can_chroot (void)
> +{
> +  int *result = support_shared_allocate (sizeof (*result));
> +  *result = 0;
> +  support_isolate_in_subprocess (callback, result);
> +  bool ok = *result == 0;
> +  if (!ok)
> +    {
> +      static bool already_warned;
> +      if (!already_warned)
> +        {
> +          already_warned = true;
> +          errno = *result;
> +          printf ("warning: this process does not support chroot: %m\n");
> +        }
> +    }
> +  support_shared_free (result);
> +  return ok;
> +}
> diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c
> new file mode 100644
> index 0000000..030f124
> --- /dev/null
> +++ b/support/support_capture_subprocess.c
> @@ -0,0 +1,108 @@
> +/* Capture output from a subprocess.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/capture_subprocess.h>
> +
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <support/xsocket.h>
> +
> +static void
> +transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream)
> +{
> +  if (pfd->revents != 0)
> +    {
> +      char buf[1024];
> +      ssize_t ret = TEMP_FAILURE_RETRY (read (pfd->fd, buf, sizeof (buf)));
> +      if (ret < 0)
> +        {
> +          support_record_failure ();
> +          printf ("error: reading from subprocess %s: %m", what);
> +          pfd->events = 0;
> +          pfd->revents = 0;
> +        }
> +      else if (ret == 0)
> +        {
> +          /* EOF reached.  Stop listening.  */
> +          pfd->events = 0;
> +          pfd->revents = 0;
> +        }
> +      else
> +        /* Store the data just read.   */
> +        TEST_VERIFY (fwrite (buf, ret, 1, stream->out) == 1);
> +    }
> +}
> +
> +struct support_capture_subprocess
> +support_capture_subprocess (void (*callback) (void *), void *closure)
> +{
> +  struct support_capture_subprocess result;
> +  xopen_memstream (&result.out);
> +  xopen_memstream (&result.err);
> +
> +  int stdout_pipe[2];
> +  xpipe (stdout_pipe);
> +  int stderr_pipe[2];
> +  xpipe (stderr_pipe);
> +
> +  TEST_VERIFY (fflush (stdout) == 0);
> +  TEST_VERIFY (fflush (stderr) == 0);
> +
> +  pid_t pid = xfork ();
> +  if (pid == 0)
> +    {
> +      xclose (stdout_pipe[0]);
> +      xclose (stderr_pipe[0]);
> +      xdup2 (stdout_pipe[1], STDOUT_FILENO);
> +      xdup2 (stderr_pipe[1], STDERR_FILENO);
> +      callback (closure);
> +      _exit (0);
> +    }
> +  xclose (stdout_pipe[1]);
> +  xclose (stderr_pipe[1]);
> +
> +  struct pollfd fds[2] =
> +    {
> +      { .fd = stdout_pipe[0], .events = POLLIN },
> +      { .fd = stderr_pipe[0], .events = POLLIN },
> +    };
> +
> +  do
> +    {
> +      xpoll (fds, 2, -1);
> +      transfer ("stdout", &fds[0], &result.out);
> +      transfer ("stderr", &fds[1], &result.err);
> +    }
> +  while (fds[0].events != 0 || fds[1].events != 0);
> +  xclose (stdout_pipe[0]);
> +  xclose (stderr_pipe[0]);
> +
> +  xfclose_memstream (&result.out);
> +  xfclose_memstream (&result.err);
> +  xwaitpid (pid, &result.status, 0);
> +  return result;
> +}
> +
> +void
> +support_capture_subprocess_free (struct support_capture_subprocess *p)
> +{
> +  free (p->out.buffer);
> +  free (p->err.buffer);
> +}
> diff --git a/support/support_capture_subprocess_check.c b/support/support_capture_subprocess_check.c
> new file mode 100644
> index 0000000..708c89f
> --- /dev/null
> +++ b/support/support_capture_subprocess_check.c
> @@ -0,0 +1,67 @@
> +/* Verify capture output from a subprocess.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <support/capture_subprocess.h>
> +#include <support/check.h>
> +
> +static void
> +print_context (const char *context, bool *failed)
> +{
> +  if (*failed)
> +    /* Do not duplicate message.  */
> +    return;
> +  support_record_failure ();
> +  printf ("error: subprocess failed: %s\n", context);
> +}
> +
> +void
> +support_capture_subprocess_check (struct support_capture_subprocess *proc,
> +                                  const char *context, int status,
> +                                  int allowed)
> +{
> +  TEST_VERIFY ((allowed & sc_allow_none)
> +               || (allowed & sc_allow_stdout)
> +               || (allowed & sc_allow_stderr));
> +  TEST_VERIFY (!((allowed & sc_allow_none)
> +                 && ((allowed & sc_allow_stdout)
> +                     || (allowed & sc_allow_stderr))));
> +
> +  bool failed = false;
> +  if (proc->status != status)
> +    {
> +      print_context (context, &failed);
> +      printf ("error:   expected exit status: %d\n", status);
> +      printf ("error:   actual exit status:   %d\n", status);
> +    }
> +  if (!(allowed & sc_allow_stdout) && proc->out.length != 0)
> +    {
> +      print_context (context, &failed);
> +      printf ("error:   unexpected output from subprocess\n");
> +      fwrite (proc->out.buffer, proc->out.length, 1, stdout);
> +      puts ("\n");
> +    }
> +  if (!(allowed & sc_allow_stderr) && proc->err.length != 0)
> +    {
> +      print_context (context, &failed);
> +      printf ("error:   unexpected error output from subprocess\n");
> +      fwrite (proc->err.buffer, proc->err.length, 1, stdout);
> +      puts ("\n");
> +    }
> +}
> diff --git a/support/support_enter_network_namespace.c b/support/support_enter_network_namespace.c
> new file mode 100644
> index 0000000..28b0ee2
> --- /dev/null
> +++ b/support/support_enter_network_namespace.c
> @@ -0,0 +1,75 @@
> +/* Enter a network namespace.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/namespace.h>
> +
> +#include <net/if.h>
> +#include <sched.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/xsocket.h>
> +#include <support/xunistd.h>
> +#include <sys/ioctl.h>
> +#include <unistd.h>
> +
> +static bool in_uts_namespace;
> +
> +bool
> +support_enter_network_namespace (void)
> +{
> +#ifdef CLONE_NEWUTS
> +  if (unshare (CLONE_NEWUTS) == 0)
> +    in_uts_namespace = true;
> +  else
> +    printf ("warning: unshare (CLONE_NEWUTS) failed: %m\n");
> +#endif
> +
> +#ifdef CLONE_NEWNET
> +  if (unshare (CLONE_NEWNET) == 0)
> +    {
> +      /* Bring up the loopback interface.  */
> +      int fd = xsocket (AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
> +      struct ifreq req;
> +      strcpy (req.ifr_name, "lo");
> +      TEST_VERIFY_EXIT (ioctl (fd, SIOCGIFFLAGS, &req) == 0);
> +      bool already_up = req.ifr_flags & IFF_UP;
> +      if (already_up)
> +        /* This means that we likely have not achieved isolation from
> +           the parent namespace.  */
> +        printf ("warning: loopback interface already exists"
> +                " in new network namespace\n");
> +      else
> +        {
> +          req.ifr_flags |= IFF_UP | IFF_RUNNING;
> +          TEST_VERIFY_EXIT (ioctl (fd, SIOCSIFFLAGS, &req) == 0);
> +        }
> +      xclose (fd);
> +
> +      return !already_up;
> +    }
> +#endif
> +  printf ("warning: could not enter network namespace\n");
> +  return false;
> +}
> +
> +bool
> +support_in_uts_namespace (void)
> +{
> +  return in_uts_namespace;
> +}
> diff --git a/support/support_format_address_family.c b/support/support_format_address_family.c
> new file mode 100644
> index 0000000..5d42c42
> --- /dev/null
> +++ b/support/support_format_address_family.c
> @@ -0,0 +1,35 @@
> +/* Convert an address family to a string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <support/support.h>
> +
> +char *
> +support_format_address_family (int family)
> +{
> +  switch (family)
> +    {
> +    case AF_INET:
> +      return xstrdup ("INET");
> +    case AF_INET6:
> +      return xstrdup ("INET6");
> +    default:
> +      return xasprintf ("<unknown address family %d>", family);
> +    }
> +}
> diff --git a/support/support_format_addrinfo.c b/support/support_format_addrinfo.c
> new file mode 100644
> index 0000000..eedb030
> --- /dev/null
> +++ b/support/support_format_addrinfo.c
> @@ -0,0 +1,239 @@
> +/* Convert struct addrinfo values to a string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <arpa/inet.h>
> +#include <errno.h>
> +#include <stdio.h>
> +#include <support/support.h>
> +#include <support/xmemstream.h>
> +
> +static size_t
> +socket_address_length (int family)
> +{
> +  switch (family)
> +    {
> +    case AF_INET:
> +      return sizeof (struct sockaddr_in);
> +    case AF_INET6:
> +      return sizeof (struct sockaddr_in6);
> +    default:
> +      return -1;
> +    }
> +}
> +
> +static void
> +format_ai_flags_1 (FILE *out, struct addrinfo *ai, int flag, const char *name,
> +                   int * flags_printed)
> +{
> +  if ((ai->ai_flags & flag) != 0)
> +    fprintf (out, " %s", name);
> +  *flags_printed |= flag;
> +}
> +
> +static void
> +format_ai_flags (FILE *out, struct addrinfo *ai)
> +{
> +  if (ai == NULL)
> +    return;
> +
> +  if (ai->ai_flags != 0)
> +    {
> +      fprintf (out, "flags:");
> +      int flags_printed = 0;
> +#define FLAG(flag) format_ai_flags_1 (out, ai, flag, #flag, &flags_printed)
> +      FLAG (AI_PASSIVE);
> +      FLAG (AI_CANONNAME);
> +      FLAG (AI_NUMERICHOST);
> +      FLAG (AI_V4MAPPED);
> +      FLAG (AI_ALL);
> +      FLAG (AI_ADDRCONFIG);
> +      FLAG (AI_IDN);
> +      FLAG (AI_CANONIDN);
> +      FLAG (AI_IDN_ALLOW_UNASSIGNED);
> +      FLAG (AI_IDN_USE_STD3_ASCII_RULES);
> +      FLAG (AI_NUMERICSERV);
> +#undef FLAG
> +      int remaining = ai->ai_flags & ~flags_printed;
> +      if (remaining != 0)
> +        fprintf (out, " %08x", remaining);
> +      fprintf (out, "\n");
> +    }
> +
> +  /* Report flag mismatches within the list.  */
> +  int flags = ai->ai_flags;
> +  int index = 1;
> +  ai = ai->ai_next;
> +  while (ai != NULL)
> +    {
> +      if (ai->ai_flags != flags)
> +        fprintf (out, "error: flags at %d: 0x%x expected, 0x%x actual\n",
> +                 index, flags, ai->ai_flags);
> +      ai = ai->ai_next;
> +      ++index;
> +    }
> +}
> +
> +static void
> +format_ai_canonname (FILE *out, struct addrinfo *ai)
> +{
> +  if (ai == NULL)
> +    return;
> +  if (ai->ai_canonname != NULL)
> +    fprintf (out, "canonname: %s\n", ai->ai_canonname);
> +
> +  /* Report incorrectly set ai_canonname fields on subsequent list
> +     entries.  */
> +  int index = 1;
> +  ai = ai->ai_next;
> +  while (ai != NULL)
> +    {
> +      if (ai->ai_canonname != NULL)
> +        fprintf (out, "error: canonname set at %d: %s\n",
> +                 index, ai->ai_canonname);
> +      ai = ai->ai_next;
> +      ++index;
> +    }
> +}
> +
> +static void
> +format_ai_one (FILE *out, struct addrinfo *ai)
> +{
> +  {
> +    char type_buf[32];
> +    const char *type_str;
> +    char proto_buf[32];
> +    const char *proto_str;
> +
> +    /* ai_socktype */
> +    switch (ai->ai_socktype)
> +      {
> +      case SOCK_RAW:
> +        type_str = "RAW";
> +        break;
> +      case SOCK_DGRAM:
> +        type_str = "DGRAM";
> +        break;
> +      case SOCK_STREAM:
> +        type_str = "STREAM";
> +        break;
> +      default:
> +        snprintf (type_buf, sizeof (type_buf), "%d", ai->ai_socktype);
> +        type_str = type_buf;
> +      }
> +
> +    /* ai_protocol */
> +    switch (ai->ai_protocol)
> +      {
> +      case IPPROTO_IP:
> +        proto_str = "IP";
> +        break;
> +      case IPPROTO_UDP:
> +        proto_str = "UDP";
> +        break;
> +      case IPPROTO_TCP:
> +        proto_str = "TCP";
> +        break;
> +      default:
> +        snprintf (proto_buf, sizeof (proto_buf), "%d", ai->ai_protocol);
> +        proto_str = proto_buf;
> +      }
> +    fprintf (out, "address: %s/%s", type_str, proto_str);
> +  }
> +
> +  /* ai_addrlen */
> +  if (ai->ai_addrlen != socket_address_length (ai->ai_family))
> +    {
> +      char *family = support_format_address_family (ai->ai_family);
> +      fprintf (out, "error: invalid address length %d for %s\n",
> +               ai->ai_addrlen, family);
> +      free (family);
> +    }
> +
> +  /* ai_addr */
> +  {
> +    char buf[128];
> +    uint16_t port;
> +    const char *ret;
> +    switch (ai->ai_family)
> +      {
> +      case AF_INET:
> +        {
> +          struct sockaddr_in *sin = (struct sockaddr_in *) ai->ai_addr;
> +          ret = inet_ntop (AF_INET, &sin->sin_addr, buf, sizeof (buf));
> +          port = sin->sin_port;
> +        }
> +        break;
> +      case AF_INET6:
> +        {
> +          struct sockaddr_in6 *sin = (struct sockaddr_in6 *) ai->ai_addr;
> +          ret = inet_ntop (AF_INET6, &sin->sin6_addr, buf, sizeof (buf));
> +          port = sin->sin6_port;
> +        }
> +        break;
> +      default:
> +        errno = EAFNOSUPPORT;
> +        ret = NULL;
> +      }
> +    if (ret == NULL)
> +        fprintf (out, "error: inet_top failed: %m\n");
> +    else
> +      fprintf (out, " %s %u\n", buf, ntohs (port));
> +  }
> +}
> +
> +/* Format all the addresses in one address family.  */
> +static void
> +format_ai_family (FILE *out, struct addrinfo *ai, int family)
> +{
> +  while (ai)
> +    {
> +      if (ai->ai_family == family)
> +        format_ai_one (out, ai);
> +      ai = ai->ai_next;
> +    }
> +}
> +
> +char *
> +support_format_addrinfo (struct addrinfo *ai, int ret)
> +{
> +  int errno_copy = errno;
> +
> +  struct xmemstream mem;
> +  xopen_memstream (&mem);
> +  if (ret != 0)
> +    {
> +      fprintf (mem.out, "error: %s\n", gai_strerror (ret));
> +      if (ret == EAI_SYSTEM)
> +        {
> +          errno = errno_copy;
> +          fprintf (mem.out, "error: %m\n");
> +        }
> +    }
> +  else
> +    {
> +      format_ai_flags (mem.out, ai);
> +      format_ai_canonname (mem.out, ai);
> +      format_ai_family (mem.out, ai, AF_INET);
> +      format_ai_family (mem.out, ai, AF_INET6);
> +    }
> +
> +  xfclose_memstream (&mem);
> +  return mem.buffer;
> +}
> diff --git a/support/support_format_dns_packet.c b/support/support_format_dns_packet.c
> new file mode 100644
> index 0000000..2992c57
> --- /dev/null
> +++ b/support/support_format_dns_packet.c
> @@ -0,0 +1,222 @@
> +/* Convert a DNS packet to a human-readable representation.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <arpa/inet.h>
> +#include <resolv.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/xmemstream.h>
> +
> +struct in_buffer
> +{
> +  const unsigned char *data;
> +  size_t size;
> +};
> +
> +static inline bool
> +extract_8 (struct in_buffer *in, unsigned char *value)
> +{
> +  if (in->size == 0)
> +    return false;
> +  *value = in->data[0];
> +  ++in->data;
> +  --in->size;
> +  return true;
> +}
> +
> +static inline bool
> +extract_16 (struct in_buffer *in, unsigned short *value)
> +{
> +  if (in->size < 2)
> +    return false;
> +  *value = (in->data[0] << 8) | in->data[1];
> +  in->data += 2;
> +  in->size -= 2;
> +  return true;
> +}
> +
> +static inline bool
> +extract_32 (struct in_buffer *in, unsigned *value)
> +{
> +  if (in->size < 4)
> +    return false;
> +  unsigned a = in->data[0];
> +  unsigned b = in->data[1];
> +  unsigned c = in->data[2];
> +  unsigned d = in->data[3];
> +  *value = (a << 24) | (b << 16) | (c << 8) | d;
> +  in->data += 4;
> +  in->size -= 4;
> +  return true;
> +}
> +
> +static inline bool
> +extract_bytes (struct in_buffer *in, size_t length, struct in_buffer *value)
> +{
> +  if (in->size < length)
> +    return false;
> +  *value = (struct in_buffer) {in->data, length};
> +  in->data += length;
> +  in->size -= length;
> +  return true;
> +}
> +
> +struct dname
> +{
> +  char name[MAXDNAME + 1];
> +};
> +
> +static bool
> +extract_name (struct in_buffer full, struct in_buffer *in, struct dname *value)
> +{
> +  const unsigned char *full_end = full.data + full.size;
> +  /* Sanity checks; these indicate buffer misuse.  */
> +  TEST_VERIFY_EXIT
> +    (!(in->data < full.data || in->data > full_end
> +       || in->size > (size_t) (full_end - in->data)));
> +  int ret = dn_expand (full.data, full_end, in->data,
> +                       value->name, sizeof (value->name));
> +  if (ret < 0)
> +    return false;
> +  in->data += ret;
> +  in->size -= ret;
> +  return true;
> +}
> +
> +char *
> +support_format_dns_packet (const unsigned char *buffer, size_t length)
> +{
> +  struct in_buffer full = { buffer, length };
> +  struct in_buffer in = full;
> +  struct xmemstream mem;
> +  xopen_memstream (&mem);
> +
> +  unsigned short txnid;
> +  unsigned short flags;
> +  unsigned short qdcount;
> +  unsigned short ancount;
> +  unsigned short nscount;
> +  unsigned short adcount;
> +  if (!(extract_16 (&in, &txnid)
> +        && extract_16 (&in, &flags)
> +        && extract_16 (&in, &qdcount)
> +        && extract_16 (&in, &ancount)
> +        && extract_16 (&in, &nscount)
> +        && extract_16 (&in, &adcount)))
> +    {
> +      fprintf (mem.out, "error: could not parse DNS header\n");
> +      goto out;
> +    }
> +  if (qdcount != 1)
> +    {
> +      fprintf (mem.out, "error: question count is %d, not 1\n", qdcount);
> +      goto out;
> +    }
> +  struct dname qname;
> +  if (!extract_name (full, &in, &qname))
> +    {
> +      fprintf (mem.out, "error: malformed QNAME\n");
> +      goto out;
> +    }
> +  unsigned short qtype;
> +  unsigned short qclass;
> +  if (!(extract_16 (&in, &qtype)
> +        && extract_16 (&in, &qclass)))
> +    {
> +      fprintf (mem.out, "error: malformed question\n");
> +      goto out;
> +    }
> +  if (qtype != T_A && qtype != T_AAAA && qtype != T_PTR)
> +    {
> +      fprintf (mem.out, "error: unsupported QTYPE %d\n", qtype);
> +      goto out;
> +    }
> +
> +  fprintf (mem.out, "name: %s\n", qname.name);
> +
> +  for (int i = 0; i < ancount; ++i)
> +    {
> +      struct dname rname;
> +      if (!extract_name (full, &in, &rname))
> +        {
> +          fprintf (mem.out, "error: malformed record name\n");
> +          goto out;
> +        }
> +      unsigned short rtype;
> +      unsigned short rclass;
> +      unsigned ttl;
> +      unsigned short rdlen;
> +      struct in_buffer rdata;
> +      if (!(extract_16 (&in, &rtype)
> +            && extract_16 (&in, &rclass)
> +            && extract_32 (&in, &ttl)
> +            && extract_16 (&in, &rdlen)
> +            && extract_bytes (&in, rdlen, &rdata)))
> +        {
> +          fprintf (mem.out, "error: malformed record header\n");
> +          goto out;
> +        }
> +      /* Skip non-matching record types.  */
> +      if ((rtype != qtype && rtype != T_CNAME) || rclass != qclass)
> +        continue;
> +      switch (rtype)
> +        {
> +        case T_A:
> +          if (rdlen == 4)
> +              fprintf (mem.out, "address: %d.%d.%d.%d\n",
> +                       rdata.data[0],
> +                       rdata.data[1],
> +                       rdata.data[2],
> +                       rdata.data[3]);
> +          else
> +            fprintf (mem.out, "error: A record of size %d: %s\n",
> +                     rdlen, rname.name);
> +          break;
> +        case T_AAAA:
> +          {
> +            if (rdlen == 16)
> +              {
> +                char buf[100];
> +                if (inet_ntop (AF_INET6, rdata.data, buf, sizeof (buf)) == NULL)
> +                  fprintf (mem.out, "error: AAAA record decoding failed: %m\n");
> +                else
> +                  fprintf (mem.out, "address: %s\n", buf);
> +              }
> +            else
> +              fprintf (mem.out, "error: AAAA record of size %d: %s\n",
> +                       rdlen, rname.name);
> +          }
> +          break;
> +        case T_CNAME:
> +        case T_PTR:
> +          {
> +            struct dname name;
> +            if (extract_name (full, &rdata, &name))
> +              fprintf (mem.out, "name: %s\n", name.name);
> +            else
> +              fprintf (mem.out, "error: malformed CNAME/PTR record\n");
> +          }
> +        }
> +    }
> +
> + out:
> +  xfclose_memstream (&mem);
> +  return mem.buffer;
> +}
> diff --git a/support/support_format_herrno.c b/support/support_format_herrno.c
> new file mode 100644
> index 0000000..493d6ae
> --- /dev/null
> +++ b/support/support_format_herrno.c
> @@ -0,0 +1,45 @@
> +/* Convert a h_errno error code to a string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <support/support.h>
> +
> +char *
> +support_format_herrno (int code)
> +{
> +  const char *errstr;
> +  switch (code)
> +    {
> +    case HOST_NOT_FOUND:
> +      errstr = "HOST_NOT_FOUND";
> +      break;
> +    case NO_ADDRESS:
> +      errstr = "NO_ADDRESS";
> +      break;
> +    case NO_RECOVERY:
> +      errstr = "NO_RECOVERY";
> +      break;
> +    case TRY_AGAIN:
> +      errstr = "TRY_AGAIN";
> +      break;
> +    default:
> +      return xasprintf ("<invalid h_errno value %d>\n", code);
> +    }
> +  return xstrdup (errstr);
> +}
> diff --git a/support/support_format_hostent.c b/support/support_format_hostent.c
> new file mode 100644
> index 0000000..5b5f260
> --- /dev/null
> +++ b/support/support_format_hostent.c
> @@ -0,0 +1,75 @@
> +/* Convert a struct hostent object to a string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <arpa/inet.h>
> +#include <stdio.h>
> +#include <support/support.h>
> +#include <support/xmemstream.h>
> +
> +static int
> +address_length (int family)
> +{
> +  switch (family)
> +    {
> +    case AF_INET:
> +      return 4;
> +    case AF_INET6:
> +      return 16;
> +    }
> +  return -1;
> +}
> +
> +char *
> +support_format_hostent (struct hostent *h)
> +{
> +  if (h == NULL)
> +    {
> +      char *value = support_format_herrno (h_errno);
> +      char *result = xasprintf ("error: %s\n", value);
> +      free (value);
> +      return result;
> +    }
> +
> +  struct xmemstream mem;
> +  xopen_memstream (&mem);
> +
> +  fprintf (mem.out, "name: %s\n", h->h_name);
> +  for (char **alias = h->h_aliases; *alias != NULL; ++alias)
> +    fprintf (mem.out, "alias: %s\n", *alias);
> +  for (unsigned i = 0; h->h_addr_list[i] != NULL; ++i)
> +    {
> +      char buf[128];
> +      if (inet_ntop (h->h_addrtype, h->h_addr_list[i],
> +                     buf, sizeof (buf)) == NULL)
> +        fprintf (mem.out, "error: inet_ntop failed: %m\n");
> +      else
> +        fprintf (mem.out, "address: %s\n", buf);
> +    }
> +  if (h->h_length != address_length (h->h_addrtype))
> +    {
> +      char *family = support_format_address_family (h->h_addrtype);
> +      fprintf (mem.out, "error: invalid address length %d for %s\n",
> +               h->h_length, family);
> +      free (family);
> +    }
> +
> +  xfclose_memstream (&mem);
> +  return mem.buffer;
> +}
> diff --git a/support/support_format_netent.c b/support/support_format_netent.c
> new file mode 100644
> index 0000000..020f572
> --- /dev/null
> +++ b/support/support_format_netent.c
> @@ -0,0 +1,52 @@
> +/* Convert a struct netent object to a string.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/format_nss.h>
> +
> +#include <arpa/inet.h>
> +#include <stdio.h>
> +#include <support/support.h>
> +#include <support/xmemstream.h>
> +
> +char *
> +support_format_netent (struct netent *e)
> +{
> +  if (e == NULL)
> +    {
> +      char *value = support_format_herrno (h_errno);
> +      char *result = xasprintf ("error: %s\n", value);
> +      free (value);
> +      return result;
> +    }
> +
> +  struct xmemstream mem;
> +  xopen_memstream (&mem);
> +
> +  if (e->n_name != NULL)
> +    fprintf (mem.out, "name: %s\n", e->n_name);
> +  for (char **ap = e->n_aliases; *ap != NULL; ++ap)
> +    fprintf (mem.out, "alias: %s\n", *ap);
> +  if (e->n_addrtype != AF_INET)
> +    fprintf (mem.out, "addrtype: %d\n", e->n_addrtype);
> +  /* On alpha, e->n_net is an unsigned long.  */
> +  unsigned int n_net = e->n_net;
> +  fprintf (mem.out, "net: 0x%08x\n", n_net);
> +
> +  xfclose_memstream (&mem);
> +  return mem.buffer;
> +}
> diff --git a/support/support_isolate_in_subprocess.c b/support/support_isolate_in_subprocess.c
> new file mode 100644
> index 0000000..cf48614
> --- /dev/null
> +++ b/support/support_isolate_in_subprocess.c
> @@ -0,0 +1,38 @@
> +/* Run a function in a subprocess.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +
> +void
> +support_isolate_in_subprocess (void (*callback) (void *), void *closure)
> +{
> +  pid_t pid = xfork ();
> +  if (pid == 0)
> +    {
> +      /* Child process.  */
> +      callback (closure);
> +      _exit (0);
> +    }
> +
> +  /* Parent process.  */
> +  int status;
> +  xwaitpid (pid, &status, 0);
> +  if (status != 0)
> +    FAIL_EXIT1 ("child process exited with status %d", status);
> +}
> diff --git a/support/support_record_failure.c b/support/support_record_failure.c
> new file mode 100644
> index 0000000..684055c
> --- /dev/null
> +++ b/support/support_record_failure.c
> @@ -0,0 +1,106 @@
> +/* Global test failure counter.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/test-driver.h>
> +
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/mman.h>
> +#include <unistd.h>
> +
> +/* This structure keeps track of test failures.  The counter is
> +   incremented on each failure.  The failed member is set to true if a
> +   failure is detected, so that even if the counter wraps around to
> +   zero, the failure of a test can be detected.
> +
> +   The init constructor function below puts *state on a shared
> +   annonymous mapping, so that failure reports from subprocesses
> +   propagate to the parent process.  */
> +struct test_failures
> +{
> +  unsigned int counter;
> +  unsigned int failed;
> +};
> +static struct test_failures *state;
> +
> +static __attribute__ ((constructor)) void
> +init (void)
> +{
> +  void *ptr = mmap (NULL, sizeof (*state), PROT_READ | PROT_WRITE,
> +                    MAP_ANONYMOUS | MAP_SHARED, -1, 0);
> +  if (ptr == MAP_FAILED)
> +    {
> +      printf ("error: could not map %zu bytes: %m\n", sizeof (*state));
> +      exit (1);
> +    }
> +  /* Zero-initialization of the struct is sufficient.  */
> +  state = ptr;
> +}
> +
> +void
> +support_record_failure (void)
> +{
> +  if (state == NULL)
> +    {
> +      write_message
> +        ("error: support_record_failure called without initialization\n");
> +      _exit (1);
> +    }
> +  /* Relaxed MO is sufficient because we are only interested in the
> +     values themselves, in isolation.  */
> +  __atomic_store_n (&state->failed, 1, __ATOMIC_RELEASE);
> +  __atomic_add_fetch (&state->counter, 1, __ATOMIC_RELEASE);
> +}
> +
> +int
> +support_report_failure (int status)
> +{
> +  if (state == NULL)
> +    {
> +      write_message
> +        ("error: support_report_failure called without initialization\n");
> +      return 1;
> +    }
> +
> +  /* Relaxed MO is sufficient because acquire test result reporting
> +     assumes that exiting from the main thread happens before the
> +     error reporting via support_record_failure, which requires some
> +     form of external synchronization.  */
> +  bool failed = __atomic_load_n (&state->failed, __ATOMIC_RELAXED);
> +  if (failed)
> +    printf ("error: %u test failures\n",
> +            __atomic_load_n (&state->counter, __ATOMIC_RELAXED));
> +
> +  if ((status == 0 || status == EXIT_UNSUPPORTED) && failed)
> +    /* If we have a recorded failure, it overrides a non-failure
> +       report from the test function.  */
> +    status = 1;
> +  return status;
> +}
> +
> +void
> +support_record_failure_reset (void)
> +{
> +  /* Only used for testing the test framework, with external
> +     synchronization, but use release MO for consistency.  */
> +  __atomic_store_n (&state->failed, 0, __ATOMIC_RELAXED);
> +  __atomic_add_fetch (&state->counter, 0, __ATOMIC_RELAXED);
> +}
> diff --git a/support/support_run_diff.c b/support/support_run_diff.c
> new file mode 100644
> index 0000000..f5155de
> --- /dev/null
> +++ b/support/support_run_diff.c
> @@ -0,0 +1,76 @@
> +/* Invoke the system diff tool to compare two strings.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/run_diff.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/temp_file.h>
> +#include <support/xunistd.h>
> +#include <sys/wait.h>
> +
> +static char *
> +write_to_temp_file (const char *prefix, const char *str)
> +{
> +  char *template = xasprintf ("run_diff-%s", prefix);
> +  char *name = NULL;
> +  int fd = create_temp_file (template, &name);
> +  TEST_VERIFY_EXIT (fd >= 0);
> +  free (template);
> +  xwrite (fd, str, strlen (str));
> +  xclose (fd);
> +  return name;
> +}
> +
> +void
> +support_run_diff (const char *left_label, const char *left,
> +                  const char *right_label, const char *right)
> +{
> +  /* Ensure that the diff command output is ordered properly with
> +     standard output.  */
> +  TEST_VERIFY_EXIT (fflush (stdout) == 0);
> +
> +  char *left_path = write_to_temp_file ("left-diff", left);
> +  char *right_path = write_to_temp_file ("right-diff", right);
> +
> +  pid_t pid = xfork ();
> +  if (pid == 0)
> +    {
> +      execlp ("diff", "diff", "-u",
> +              "--label", left_label, "--label", right_label,
> +              "--", left_path, right_path,
> +              NULL);
> +      _exit (17);
> +    }
> +  else
> +    {
> +      int status;
> +      xwaitpid (pid, &status, 0);
> +      if (!WIFEXITED (status) || WEXITSTATUS (status) != 1)
> +        printf ("warning: could not run diff, exit status: %d\n"
> +                "*** %s ***\n%s\n"
> +                "*** %s ***\n%s\n",
> +                status, left_label, left, right_label, right);
> +    }
> +
> +  free (right_path);
> +  free (left_path);
> +}
> diff --git a/support/support_shared_allocate.c b/support/support_shared_allocate.c
> new file mode 100644
> index 0000000..c2ca7c2
> --- /dev/null
> +++ b/support/support_shared_allocate.c
> @@ -0,0 +1,59 @@
> +/* Allocate a memory region shared across processes.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <errno.h>
> +#include <stddef.h>
> +#include <support/support.h>
> +#include <support/xunistd.h>
> +#include <sys/mman.h>
> +
> +#if defined ISO11
> +/* Header for the allocation.  It contains the size of the allocation
> +   for subsequent unmapping.  */
> +struct header
> +{
> +  size_t total_size;
> +  char data[] __attribute__ ((aligned (__alignof__ (max_align_t))));
> +};
> +
> +void *
> +support_shared_allocate (size_t size)
> +{
> +  size_t total_size = size + offsetof (struct header, data);
> +  if (total_size < size)
> +    {
> +      errno = ENOMEM;
> +      oom_error (__func__, size);
> +      return NULL;
> +    }
> +  else
> +    {
> +      struct header *result = xmmap (NULL, total_size, PROT_READ | PROT_WRITE,
> +                                     MAP_ANONYMOUS | MAP_SHARED, -1);
> +      result->total_size = total_size;
> +      return &result->data;
> +    }
> +}
> +
> +void
> +support_shared_free (void *data)
> +{
> +  struct header *header = data - offsetof (struct header, data);
> +  xmunmap (header, header->total_size);
> +}
> +#endif
> diff --git a/support/support_test_main.c b/support/support_test_main.c
> new file mode 100644
> index 0000000..914d64f
> --- /dev/null
> +++ b/support/support_test_main.c
> @@ -0,0 +1,423 @@
> +/* Main worker function for the test driver.
> +   Copyright (C) 1998-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/test-driver.h>
> +#include <support/check.h>
> +#include <support/temp_file-internal.h>
> +
> +#include <assert.h>
> +#include <errno.h>
> +#include <getopt.h>
> +#include <malloc.h>
> +#include <signal.h>
> +#include <stdbool.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/param.h>
> +#include <sys/resource.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <time.h>
> +#include <unistd.h>
> +
> +static const struct option default_options[] =
> +{
> +  TEST_DEFAULT_OPTIONS
> +  { NULL, 0, NULL, 0 }
> +};
> +
> +/* Show people how to run the program.  */
> +static void
> +usage (const struct option *options)
> +{
> +  size_t i;
> +
> +  printf ("Usage: %s [options]\n"
> +          "\n"
> +          "Environment Variables:\n"
> +          "  TIMEOUTFACTOR          An integer used to scale the timeout\n"
> +          "  TMPDIR                 Where to place temporary files\n"
> +          "  TEST_COREDUMPS         Do not disable coredumps if set\n"
> +          "\n",
> +          program_invocation_short_name);
> +  printf ("Options:\n");
> +  for (i = 0; options[i].name; ++i)
> +    {
> +      int indent;
> +
> +      indent = printf ("  --%s", options[i].name);
> +      if (options[i].has_arg == required_argument)
> +        indent += printf (" <arg>");
> +      printf ("%*s", 25 - indent, "");
> +      switch (options[i].val)
> +        {
> +        case 'v':
> +          printf ("Increase the output verbosity");
> +          break;
> +        case OPT_DIRECT:
> +          printf ("Run the test directly (instead of forking & monitoring)");
> +          break;
> +        case OPT_TESTDIR:
> +          printf ("Override the TMPDIR env var");
> +          break;
> +        }
> +      printf ("\n");
> +    }
> +}
> +
> +/* The PID of the test process.  */
> +static pid_t test_pid;
> +
> +/* The cleanup handler passed to test_main.  */
> +static void (*cleanup_function) (void);
> +
> +/* Timeout handler.  We kill the child and exit with an error.  */
> +static void
> +__attribute__ ((noreturn))
> +signal_handler (int sig)
> +{
> +  int killed;
> +  int status;
> +
> +  assert (test_pid > 1);
> +  /* Kill the whole process group.  */
> +  kill (-test_pid, SIGKILL);
> +  /* In case setpgid failed in the child, kill it individually too.  */
> +  kill (test_pid, SIGKILL);
> +
> +  /* Wait for it to terminate.  */
> +  int i;
> +  for (i = 0; i < 5; ++i)
> +    {
> +      killed = waitpid (test_pid, &status, WNOHANG|WUNTRACED);
> +      if (killed != 0)
> +        break;
> +
> +      /* Delay, give the system time to process the kill.  If the
> +         nanosleep() call return prematurely, all the better.  We
> +         won't restart it since this probably means the child process
> +         finally died.  */
> +      struct timespec ts;
> +      ts.tv_sec = 0;
> +      ts.tv_nsec = 100000000;
> +      nanosleep (&ts, NULL);
> +    }
> +  if (killed != 0 && killed != test_pid)
> +    {
> +      printf ("Failed to kill test process: %m\n");
> +      exit (1);
> +    }
> +
> +  if (cleanup_function != NULL)
> +    cleanup_function ();
> +
> +  if (sig == SIGINT)
> +    {
> +      signal (sig, SIG_DFL);
> +      raise (sig);
> +    }
> +
> +  if (killed == 0 || (WIFSIGNALED (status) && WTERMSIG (status) == SIGKILL))
> +    puts ("Timed out: killed the child process");
> +  else if (WIFSTOPPED (status))
> +    printf ("Timed out: the child process was %s\n",
> +            strsignal (WSTOPSIG (status)));
> +  else if (WIFSIGNALED (status))
> +    printf ("Timed out: the child process got signal %s\n",
> +            strsignal (WTERMSIG (status)));
> +  else
> +    printf ("Timed out: killed the child process but it exited %d\n",
> +            WEXITSTATUS (status));
> +
> +  /* Exit with an error.  */
> +  exit (1);
> +}
> +
> +/* Run test_function or test_function_argv.  */
> +static int
> +run_test_function (int argc, char **argv, const struct test_config *config)
> +{
> +  if (config->test_function != NULL)
> +    return config->test_function ();
> +  else if (config->test_function_argv != NULL)
> +    return config->test_function_argv (argc, argv);
> +  else
> +    {
> +      printf ("error: no test function defined\n");
> +      exit (1);
> +    }
> +}
> +
> +static bool test_main_called;
> +
> +const char *test_dir = NULL;
> +unsigned int test_verbose = 0;
> +
> +/* If test failure reporting has been linked in, it may contribute
> +   additional test failures.  */
> +static int
> +adjust_exit_status (int status)
> +{
> +  if (support_report_failure != NULL)
> +    return support_report_failure (status);
> +  return status;
> +}
> +
> +int
> +support_test_main (int argc, char **argv, const struct test_config *config)
> +{
> +  if (test_main_called)
> +    {
> +      printf ("error: test_main called for a second time\n");
> +      exit (1);
> +    }
> +  test_main_called = true;
> +  const struct option *options;
> +  if (config->options != NULL)
> +    options = config->options;
> +  else
> +    options = default_options;
> +
> +  cleanup_function = config->cleanup_function;
> +
> +  int direct = 0;       /* Directly call the test function?  */
> +  int status;
> +  int opt;
> +  unsigned int timeoutfactor = 1;
> +  pid_t termpid;
> +
> +  if (!config->no_mallopt)
> +    {
> +      /* Make uses of freed and uninitialized memory known.  Do not
> +         pull in a definition for mallopt if it has not been defined
> +         already.  */
> +      extern __typeof__ (mallopt) mallopt __attribute__ ((weak));
> +      if (mallopt != NULL)
> +        mallopt (M_PERTURB, 42);
> +    }
> +
> +  while ((opt = getopt_long (argc, argv, "+", options, NULL)) != -1)
> +    switch (opt)
> +      {
> +      case '?':
> +        usage (options);
> +        exit (1);
> +      case 'v':
> +        ++test_verbose;
> +        break;
> +      case OPT_DIRECT:
> +        direct = 1;
> +        break;
> +      case OPT_TESTDIR:
> +        test_dir = optarg;
> +        break;
> +      default:
> +        if (config->cmdline_function != NULL)
> +          config->cmdline_function (opt);
> +      }
> +
> +  /* If set, read the test TIMEOUTFACTOR value from the environment.
> +     This value is used to scale the default test timeout values. */
> +  char *envstr_timeoutfactor = getenv ("TIMEOUTFACTOR");
> +  if (envstr_timeoutfactor != NULL)
> +    {
> +      char *envstr_conv = envstr_timeoutfactor;
> +      unsigned long int env_fact;
> +
> +      env_fact = strtoul (envstr_timeoutfactor, &envstr_conv, 0);
> +      if (*envstr_conv == '\0' && envstr_conv != envstr_timeoutfactor)
> +        timeoutfactor = MAX (env_fact, 1);
> +    }
> +
> +  /* Set TMPDIR to specified test directory.  */
> +  if (test_dir != NULL)
> +    {
> +      setenv ("TMPDIR", test_dir, 1);
> +
> +      if (chdir (test_dir) < 0)
> +        {
> +          printf ("chdir: %m\n");
> +          exit (1);
> +        }
> +    }
> +  else
> +    {
> +      test_dir = getenv ("TMPDIR");
> +      if (test_dir == NULL || test_dir[0] == '\0')
> +        test_dir = "/tmp";
> +    }
> +  if (support_set_test_dir != NULL)
> +    support_set_test_dir (test_dir);
> +
> +  int timeout = config->timeout;
> +  if (timeout == 0)
> +    timeout =  DEFAULT_TIMEOUT;
> +
> +  /* Make sure we see all message, even those on stdout.  */
> +  setvbuf (stdout, NULL, _IONBF, 0);
> +
> +  /* Make sure temporary files are deleted.  */
> +  if (support_delete_temp_files != NULL)
> +      atexit (support_delete_temp_files);
> +
> +  /* Correct for the possible parameters.  */
> +  argv[optind - 1] = argv[0];
> +  argv += optind - 1;
> +  argc -= optind - 1;
> +
> +  /* Call the initializing function, if one is available.  */
> +  if (config->prepare_function != NULL)
> +    config->prepare_function (argc, argv);
> +
> +  const char *envstr_direct = getenv ("TEST_DIRECT");
> +  if (envstr_direct != NULL)
> +    {
> +      FILE *f = fopen (envstr_direct, "w");
> +      if (f == NULL)
> +        {
> +          printf ("cannot open TEST_DIRECT output file '%s': %m\n",
> +                  envstr_direct);
> +          exit (1);
> +        }
> +
> +      fprintf (f, "timeout=%u\ntimeoutfactor=%u\n",
> +               config->timeout, timeoutfactor);
> +      if (config->expected_status != 0)
> +        fprintf (f, "exit=%u\n", config->expected_status);
> +      if (config->expected_signal != 0)
> +        fprintf (f, "signal=%s\n", strsignal (config->expected_signal));
> +
> +      if (support_print_temp_files != NULL)
> +        support_print_temp_files (f);
> +
> +      fclose (f);
> +      direct = 1;
> +    }
> +
> +  bool disable_coredumps;
> +  {
> +    const char *coredumps = getenv ("TEST_COREDUMPS");
> +    disable_coredumps = coredumps == NULL || coredumps[0] == '\0';
> +  }
> +
> +  /* If we are not expected to fork run the function immediately.  */
> +  if (direct)
> +    return adjust_exit_status (run_test_function (argc, argv, config));
> +
> +  /* Set up the test environment:
> +     - prevent core dumps
> +     - set up the timer
> +     - fork and execute the function.  */
> +
> +  test_pid = fork ();
> +  if (test_pid == 0)
> +    {
> +      /* This is the child.  */
> +      if (disable_coredumps)
> +        {
> +          /* Try to avoid dumping core.  This is necessary because we
> +             run the test from the source tree, and the coredumps
> +             would end up there (and not in the build tree).  */
> +          struct rlimit core_limit;
> +          core_limit.rlim_cur = 0;
> +          core_limit.rlim_max = 0;
> +          setrlimit (RLIMIT_CORE, &core_limit);
> +        }
> +
> +      /* We put the test process in its own pgrp so that if it bogusly
> +         generates any job control signals, they won't hit the whole build.  */
> +      if (setpgid (0, 0) != 0)
> +        printf ("Failed to set the process group ID: %m\n");
> +
> +      /* Execute the test function and exit with the return value.   */
> +      exit (run_test_function (argc, argv, config));
> +    }
> +  else if (test_pid < 0)
> +    {
> +      printf ("Cannot fork test program: %m\n");
> +      exit (1);
> +    }
> +
> +  /* Set timeout.  */
> +  signal (SIGALRM, signal_handler);
> +  alarm (timeout * timeoutfactor);
> +
> +  /* Make sure we clean up if the wrapper gets interrupted.  */
> +  signal (SIGINT, signal_handler);
> +
> +  /* Wait for the regular termination.  */
> +  termpid = TEMP_FAILURE_RETRY (waitpid (test_pid, &status, 0));
> +  if (termpid == -1)
> +    {
> +      printf ("Waiting for test program failed: %m\n");
> +      exit (1);
> +    }
> +  if (termpid != test_pid)
> +    {
> +      printf ("Oops, wrong test program terminated: expected %ld, got %ld\n",
> +              (long int) test_pid, (long int) termpid);
> +      exit (1);
> +    }
> +
> +  /* Process terminated normaly without timeout etc.  */
> +  if (WIFEXITED (status))
> +    {
> +      if (config->expected_status == 0)
> +        {
> +          if (config->expected_signal == 0)
> +            /* Exit with the return value of the test.  */
> +            return adjust_exit_status (WEXITSTATUS (status));
> +          else
> +            {
> +              printf ("Expected signal '%s' from child, got none\n",
> +                      strsignal (config->expected_signal));
> +              exit (1);
> +            }
> +        }
> +      else
> +        {
> +          /* Non-zero exit status is expected */
> +          if (WEXITSTATUS (status) != config->expected_status)
> +            {
> +              printf ("Expected status %d, got %d\n",
> +                      config->expected_status, WEXITSTATUS (status));
> +              exit (1);
> +            }
> +        }
> +      return adjust_exit_status (0);
> +    }
> +  /* Process was killed by timer or other signal.  */
> +  else
> +    {
> +      if (config->expected_signal == 0)
> +        {
> +          printf ("Didn't expect signal from child: got `%s'\n",
> +                  strsignal (WTERMSIG (status)));
> +          exit (1);
> +        }
> +      else if (WTERMSIG (status) != config->expected_signal)
> +        {
> +          printf ("Incorrect signal from child: got `%s', need `%s'\n",
> +                  strsignal (WTERMSIG (status)),
> +                  strsignal (config->expected_signal));
> +          exit (1);
> +        }
> +
> +      return adjust_exit_status (0);
> +    }
> +}
> diff --git a/support/support_test_verify_impl.c b/support/support_test_verify_impl.c
> new file mode 100644
> index 0000000..5bae38f
> --- /dev/null
> +++ b/support/support_test_verify_impl.c
> @@ -0,0 +1,33 @@
> +/* Implementation of the TEST_VERIFY and TEST_VERIFY_EXIT macros.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void
> +support_test_verify_impl (int status, const char *file, int line,
> +                          const char *expr)
> +{
> +  support_record_failure ();
> +  printf ("error: %s:%d: not true: %s\n", file, line, expr);
> +  if (status >= 0)
> +    exit (status);
> +
> +}
> diff --git a/support/support_write_file_string.c b/support/support_write_file_string.c
> new file mode 100644
> index 0000000..48e8959
> --- /dev/null
> +++ b/support/support_write_file_string.c
> @@ -0,0 +1,39 @@
> +/* Write a string to a file.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <fcntl.h>
> +#include <string.h>
> +#include <support/check.h>
> +#include <xunistd.h>
> +
> +void
> +support_write_file_string (const char *path, const char *contents)
> +{
> +  int fd = xopen (path, O_CREAT | O_TRUNC | O_WRONLY, 0666);
> +  const char *end = contents + strlen (contents);
> +  for (const char *p = contents; p < end; )
> +    {
> +      ssize_t ret = write (fd, p, end - p);
> +      if (ret < 0)
> +        FAIL_EXIT1 ("cannot write to \"%s\": %m", path);
> +      if (ret == 0)
> +        FAIL_EXIT1 ("zero-length write to \"%s\"", path);
> +      p += ret;
> +    }
> +  xclose (fd);
> +}
> diff --git a/support/temp_file-internal.h b/support/temp_file-internal.h
> new file mode 100644
> index 0000000..fb6cceb
> --- /dev/null
> +++ b/support/temp_file-internal.h
> @@ -0,0 +1,31 @@
> +/* Internal weak declarations for temporary file handling.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_TEMP_FILE_INTERNAL_H
> +#define SUPPORT_TEMP_FILE_INTERNAL_H
> +
> +/* These functions are called by the test driver if they are
> +   defined.  Tests should not call them directly.  */
> +
> +#include <stdio.h>
> +
> +void support_set_test_dir (const char *name) __attribute__ ((weak));
> +void support_delete_temp_files (void) __attribute__ ((weak));
> +void support_print_temp_files (FILE *) __attribute__ ((weak));
> +
> +#endif /* SUPPORT_TEMP_FILE_INTERNAL_H */
> diff --git a/support/temp_file.c b/support/temp_file.c
> new file mode 100644
> index 0000000..fdb2477
> --- /dev/null
> +++ b/support/temp_file.c
> @@ -0,0 +1,132 @@
> +/* Temporary file handling for tests.
> +   Copyright (C) 1998-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* This is required to get an mkstemp which can create large files on
> +   some 32-bit platforms. */
> +#define _FILE_OFFSET_BITS 64
> +
> +#include <support/temp_file.h>
> +#include <support/temp_file-internal.h>
> +#include <support/support.h>
> +
> +#include <paths.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +/* List of temporary files.  */
> +static struct temp_name_list
> +{
> +  struct temp_name_list *next;
> +  char *name;
> +  pid_t owner;
> +} *temp_name_list;
> +
> +/* Location of the temporary files.  Set by the test skeleton via
> +   support_set_test_dir.  The string is not be freed.  */
> +static const char *test_dir = _PATH_TMP;
> +
> +void
> +add_temp_file (const char *name)
> +{
> +  struct temp_name_list *newp
> +    = (struct temp_name_list *) xcalloc (sizeof (*newp), 1);
> +  char *newname = strdup (name);
> +  if (newname != NULL)
> +    {
> +      newp->name = newname;
> +      newp->next = temp_name_list;
> +      newp->owner = getpid ();
> +      temp_name_list = newp;
> +    }
> +  else
> +    free (newp);
> +}
> +
> +int
> +create_temp_file (const char *base, char **filename)
> +{
> +  char *fname;
> +  int fd;
> +
> +  fname = (char *) xmalloc (strlen (test_dir) + 1 + strlen (base)
> +			    + sizeof ("XXXXXX"));
> +  strcpy (stpcpy (stpcpy (stpcpy (fname, test_dir), "/"), base), "XXXXXX");
> +
> +  fd = mkstemp (fname);
> +  if (fd == -1)
> +    {
> +      printf ("cannot open temporary file '%s': %m\n", fname);
> +      free (fname);
> +      return -1;
> +    }
> +
> +  add_temp_file (fname);
> +  if (filename != NULL)
> +    *filename = fname;
> +  else
> +    free (fname);
> +
> +  return fd;
> +}
> +
> +/* Helper functions called by the test skeleton follow.  */
> +
> +void
> +support_set_test_dir (const char *path)
> +{
> +  test_dir = path;
> +}
> +
> +void
> +support_delete_temp_files (void)
> +{
> +  pid_t pid = getpid ();
> +  while (temp_name_list != NULL)
> +    {
> +      /* Only perform the removal if the path was registed in the same
> +	 process, as identified by the PID.  (This assumes that the
> +	 parent process which registered the temporary file sticks
> +	 around, to prevent PID reuse.)  */
> +      if (temp_name_list->owner == pid)
> +	{
> +	  if (remove (temp_name_list->name) != 0)
> +	    printf ("warning: could not remove temporary file: %s: %m\n",
> +		    temp_name_list->name);
> +	}
> +      free (temp_name_list->name);
> +
> +      struct temp_name_list *next = temp_name_list->next;
> +      free (temp_name_list);
> +      temp_name_list = next;
> +    }
> +}
> +
> +void
> +support_print_temp_files (FILE *f)
> +{
> +  if (temp_name_list != NULL)
> +    {
> +      struct temp_name_list *n;
> +      fprintf (f, "temp_files=(\n");
> +      for (n = temp_name_list; n != NULL; n = n->next)
> +        fprintf (f, "  '%s'\n", n->name);
> +      fprintf (f, ")\n");
> +    }
> +}
> diff --git a/support/temp_file.h b/support/temp_file.h
> new file mode 100644
> index 0000000..6fed8df
> --- /dev/null
> +++ b/support/temp_file.h
> @@ -0,0 +1,37 @@
> +/* Declarations for temporary file handling.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_TEMP_FILE_H
> +#define SUPPORT_TEMP_FILE_H
> +
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Schedule a temporary file for deletion on exit.  */
> +void add_temp_file (const char *name);
> +
> +/* Create a temporary file.  Return the opened file descriptor on
> +   success, or -1 on failure.  Write the file name to *FILENAME if
> +   FILENAME is not NULL.  In this case, the caller is expected to free
> +   *FILENAME.  */
> +int create_temp_file (const char *base, char **filename);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_TEMP_FILE_H */
> diff --git a/support/test-driver.c b/support/test-driver.c
> new file mode 100644
> index 0000000..482066d
> --- /dev/null
> +++ b/support/test-driver.c
> @@ -0,0 +1,156 @@
> +/* Main function for test programs.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* This file should be included from test cases.  It will define a
> +   main function which provides the test wrapper.
> +
> +   It assumes that the test case defines a function
> +
> +     int do_test (void);
> +
> +   and arranges for that function being called under the test wrapper.
> +   The do_test function should return 0 to indicate a passing test, 1
> +   to indicate a failing test, or 77 to indicate an unsupported test.
> +   Other result values could be used to indicate a failing test, but
> +   the result of the expression is passed to exit and exit only
> +   returns the lower 8 bits of its input.  A non-zero return with some
> +   values could cause a test to incorrectly be considered passing when
> +   it really failed.  For this reason, the function should always
> +   return 0 (EXIT_SUCCESS), 1 (EXIT_FAILURE), or 77
> +   (EXIT_UNSUPPORTED).
> +
> +   The test function may print out diagnostic or warning messages as well
> +   as messages about failures.  These messages should be printed to stdout
> +   and not stderr so that the output is properly ordered with respect to
> +   the rest of the glibc testsuite run output.
> +
> +   Several preprocessors macros can be defined before including this
> +   file.
> +
> +   The name of the do_test function can be changed with the
> +   TEST_FUNCTION macro.  It must expand to the desired function name.
> +
> +   If the test case needs access to command line parameters, it must
> +   define the TEST_FUNCTION_ARGV macro with the name of the test
> +   function.  It must have the following type:
> +
> +     int TEST_FUNCTION_ARGV (int argc, char **argv);
> +
> +   This overrides the do_test default function and is incompatible
> +   with the TEST_FUNCTION macro.
> +
> +   If PREPARE is defined, it must expand to the name of a function of
> +   the type
> +
> +     void PREPARE (int argc, char **);
> +
> +   This function will be called early, after parsing the command line,
> +   but before running the test, in the parent process which acts as
> +   the test supervisor.
> +
> +   If CLEANUP_HANDLER is defined, it must expand to the name of a
> +   function of the type
> +
> +     void CLEANUP_HANDLER (void);
> +
> +   This function will be called from the timeout (SIGALRM) signal
> +   handler.
> +
> +   If EXPECTED_SIGNAL is defined, it must expanded to a constant which
> +   denotes the expected signal number.
> +
> +   If EXPECTED_STATUS is defined, it must expand to the expected exit
> +   status.
> +
> +   If TIMEOUT is defined, it must be positive constant.  It overrides
> +   the default test timeout and is measured in seconds.
> +
> +   If TEST_NO_MALLOPT is defined, the test wrapper will not call
> +   mallopt.
> +
> +   Custom command line handling can be implemented by defining the
> +   CMDLINE_OPTION macro (after including the <getopt.h> header; this
> +   requires _GNU_SOURCE to be defined).  This macro must expand to a
> +   to a comma-separated list of braced initializers for struct option
> +   from <getopt.h>, with a trailing comma.  CMDLINE_PROCESS can be
> +   defined as the name of a function which is called to process these
> +   options.  The function is passed the option character/number and
> +   has this type:
> +
> +     void CMDLINE_PROCESS (int);
> +*/
> +
> +#include <support/test-driver.h>
> +
> +#include <string.h>
> +
> +int
> +main (int argc, char **argv)
> +{
> +  struct test_config test_config;
> +  memset (&test_config, 0, sizeof (test_config));
> +
> +#ifdef PREPARE
> +  test_config.prepare_function = (PREPARE);
> +#endif
> +
> +#if defined (TEST_FUNCTION) && defined (TEST_FUNCTON_ARGV)
> +# error TEST_FUNCTION and TEST_FUNCTION_ARGV cannot be defined at the same time
> +#endif
> +#if defined (TEST_FUNCTION)
> +  test_config.test_function = TEST_FUNCTION;
> +#elif defined (TEST_FUNCTION_ARGV)
> +  test_config.test_function_argv = TEST_FUNCTION_ARGV;
> +#else
> +  test_config.test_function = do_test;
> +#endif
> +
> +#ifdef CLEANUP_HANDLER
> +  test_config.cleanup_function = CLEANUP_HANDLER;
> +#endif
> +
> +#ifdef EXPECTED_SIGNAL
> +  test_config.expected_signal = (EXPECTED_SIGNAL);
> +#endif
> +
> +#ifdef EXPECTED_STATUS
> +  test_config.expected_status = (EXPECTED_STATUS);
> +#endif
> +
> +#ifdef TEST_NO_MALLOPT
> +  test_config.no_mallopt = 1;
> +#endif
> +
> +#ifdef TIMEOUT
> +  test_config.timeout = TIMEOUT;
> +#endif
> +
> +#ifdef CMDLINE_OPTIONS
> +  struct option options[] =
> +    {
> +      CMDLINE_OPTIONS
> +      TEST_DEFAULT_OPTIONS
> +    };
> +  test_config.options = &options;
> +#endif
> +#ifdef CMDLINE_PROCESS
> +  test_config.cmdline_function = CMDLINE_PROCESS;
> +#endif
> +
> +  return support_test_main (argc, argv, &test_config);
> +}
> diff --git a/support/test-driver.h b/support/test-driver.h
> new file mode 100644
> index 0000000..af1971a
> --- /dev/null
> +++ b/support/test-driver.h
> @@ -0,0 +1,74 @@
> +/* Interfaces for the test driver.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_TEST_DRIVER_H
> +#define SUPPORT_TEST_DRIVER_H
> +
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +struct test_config
> +{
> +  void (*prepare_function) (int argc, char **argv);
> +  int (*test_function) (void);
> +  int (*test_function_argv) (int argc, char **argv);
> +  void (*cleanup_function) (void);
> +  void (*cmdline_function) (int);
> +  const void *options;   /* Custom options if not NULL.  */
> +  int timeout;           /* Test timeout in seconds.  */
> +  int expected_status;   /* Expected exit status.  */
> +  int expected_signal;   /* If non-zero, expect termination by signal.  */
> +  char no_mallopt;       /* Boolean flag to disable mallopt.  */
> +};
> +
> +enum
> +  {
> +    /* Test exit status which indicates that the feature is
> +       unsupported. */
> +    EXIT_UNSUPPORTED = 77,
> +
> +    /* Default timeout is twenty seconds.  Tests should normally
> +       complete faster than this, but if they don't, that's abnormal
> +       (a bug) anyways.  */
> +    DEFAULT_TIMEOUT = 20,
> +
> +    /* Used for command line argument parsing.  */
> +    OPT_DIRECT = 1000,
> +    OPT_TESTDIR,
> +  };
> +
> +/* Options provided by the test driver.  */
> +#define TEST_DEFAULT_OPTIONS                            \
> +  { "verbose", no_argument, NULL, 'v' },                \
> +  { "direct", no_argument, NULL, OPT_DIRECT },          \
> +  { "test-dir", required_argument, NULL, OPT_TESTDIR }, \
> +
> +/* The directory the test should use for temporary files.  */
> +extern const char *test_dir;
> +
> +/* The number of --verbose arguments specified during program
> +   invocation.  This variable can be used to control the verbosity of
> +   tests.  */
> +extern unsigned int test_verbose;
> +
> +int support_test_main (int argc, char **argv, const struct test_config *);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_TEST_DRIVER_H */
> diff --git a/support/tst-support-namespace.c b/support/tst-support-namespace.c
> new file mode 100644
> index 0000000..a50b074
> --- /dev/null
> +++ b/support/tst-support-namespace.c
> @@ -0,0 +1,34 @@
> +/* Test entering namespaces.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdio.h>
> +#include <support/namespace.h>
> +
> +static int
> +do_test (void)
> +{
> +  if (support_become_root ())
> +    printf ("info: acquired root-like privileges\n");
> +  if (support_enter_network_namespace ())
> +    printf ("info: entered network namespace\n");
> +  if (support_in_uts_namespace ())
> +    printf ("info: also entered UTS namespace\n");
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/support/tst-support_capture_subprocess.c b/support/tst-support_capture_subprocess.c
> new file mode 100644
> index 0000000..5672fba
> --- /dev/null
> +++ b/support/tst-support_capture_subprocess.c
> @@ -0,0 +1,188 @@
> +/* Test capturing output from a subprocess.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <support/capture_subprocess.h>
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <sys/wait.h>
> +#include <unistd.h>
> +
> +/* Write one byte at *P to FD and advance *P.  Do nothing if *P is
> +   '\0'.  */
> +static void
> +transfer (const unsigned char **p, int fd)
> +{
> +  if (**p != '\0')
> +    {
> +      TEST_VERIFY (write (fd, *p, 1) == 1);
> +      ++*p;
> +    }
> +}
> +
> +/* Determine the order in which stdout and stderr are written.  */
> +enum write_mode { out_first, err_first, interleave,
> +                  write_mode_last =  interleave };
> +
> +/* Describe what to write in the subprocess.  */
> +struct test
> +{
> +  char *out;
> +  char *err;
> +  enum write_mode write_mode;
> +  int signal;
> +  int status;
> +};
> +
> +/* For use with support_capture_subprocess.  */
> +static void
> +callback (void *closure)
> +{
> +  const struct test *test = closure;
> +  bool mode_ok = false;
> +  switch (test->write_mode)
> +    {
> +    case out_first:
> +      TEST_VERIFY (fputs (test->out, stdout) >= 0);
> +      TEST_VERIFY (fflush (stdout) == 0);
> +      TEST_VERIFY (fputs (test->err, stderr) >= 0);
> +      TEST_VERIFY (fflush (stderr) == 0);
> +      mode_ok = true;
> +      break;
> +    case err_first:
> +      TEST_VERIFY (fputs (test->err, stderr) >= 0);
> +      TEST_VERIFY (fflush (stderr) == 0);
> +      TEST_VERIFY (fputs (test->out, stdout) >= 0);
> +      TEST_VERIFY (fflush (stdout) == 0);
> +      mode_ok = true;
> +      break;
> +    case interleave:
> +      {
> +        const unsigned char *pout = (const unsigned char *) test->out;
> +        const unsigned char *perr = (const unsigned char *) test->err;
> +        do
> +          {
> +            transfer (&pout, STDOUT_FILENO);
> +            transfer (&perr, STDERR_FILENO);
> +          }
> +        while (*pout != '\0' || *perr != '\0');
> +      }
> +      mode_ok = true;
> +      break;
> +    }
> +  TEST_VERIFY (mode_ok);
> +
> +  if (test->signal != 0)
> +    raise (test->signal);
> +  exit (test->status);
> +}
> +
> +/* Create a heap-allocated random string of letters.  */
> +static char *
> +random_string (size_t length)
> +{
> +  char *result = xmalloc (length + 1);
> +  for (size_t i = 0; i < length; ++i)
> +    result[i] = 'a' + (rand () % 26);
> +  result[length] = '\0';
> +  return result;
> +}
> +
> +/* Check that the specific stream from the captured subprocess matches
> +   expectations.  */
> +static void
> +check_stream (const char *what, const struct xmemstream *stream,
> +              const char *expected)
> +{
> +  if (strcmp (stream->buffer, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: captured %s data incorrect\n"
> +              "  expected: %s\n"
> +              "  actual:   %s\n",
> +              what, expected, stream->buffer);
> +    }
> +  if (stream->length != strlen (expected))
> +    {
> +      support_record_failure ();
> +      printf ("error: captured %s data length incorrect\n"
> +              "  expected: %zu\n"
> +              "  actual:   %zu\n",
> +              what, strlen (expected), stream->length);
> +    }
> +}
> +
> +static int
> +do_test (void)
> +{
> +  const int lengths[] = {0, 1, 17, 512, 20000, -1};
> +
> +  /* Test multiple combinations of support_capture_subprocess.
> +
> +     length_idx_stdout: Index into the lengths array above,
> +       controls how many bytes are written by the subprocess to
> +       standard output.
> +     length_idx_stderr: Same for standard error.
> +     write_mode: How standard output and standard error writes are
> +       ordered.
> +     signal: Exit with no signal if zero, with SIGTERM if one.
> +     status: Process exit status: 0 if zero, 3 if one.  */
> +  for (int length_idx_stdout = 0; lengths[length_idx_stdout] >= 0;
> +       ++length_idx_stdout)
> +    for (int length_idx_stderr = 0; lengths[length_idx_stderr] >= 0;
> +         ++length_idx_stderr)
> +      for (int write_mode = 0; write_mode < write_mode_last; ++write_mode)
> +        for (int signal = 0; signal < 2; ++signal)
> +          for (int status = 0; status < 2; ++status)
> +            {
> +              struct test test =
> +                {
> +                  .out = random_string (lengths[length_idx_stdout]),
> +                  .err = random_string (lengths[length_idx_stderr]),
> +                  .write_mode = write_mode,
> +                  .signal = signal * SIGTERM, /* 0 or SIGTERM.  */
> +                  .status = status * 3,       /* 0 or 3.  */
> +                };
> +              TEST_VERIFY (strlen (test.out) == lengths[length_idx_stdout]);
> +              TEST_VERIFY (strlen (test.err) == lengths[length_idx_stderr]);
> +
> +              struct support_capture_subprocess result
> +                = support_capture_subprocess (callback, &test);
> +              check_stream ("stdout", &result.out, test.out);
> +              check_stream ("stderr", &result.err, test.err);
> +              if (test.signal != 0)
> +                {
> +                  TEST_VERIFY (WIFSIGNALED (result.status));
> +                  TEST_VERIFY (WTERMSIG (result.status) == test.signal);
> +                }
> +              else
> +                {
> +                  TEST_VERIFY (WIFEXITED (result.status));
> +                  TEST_VERIFY (WEXITSTATUS (result.status) == test.status);
> +                }
> +              support_capture_subprocess_free (&result);
> +              free (test.out);
> +              free (test.err);
> +            }
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/support/tst-support_format_dns_packet.c b/support/tst-support_format_dns_packet.c
> new file mode 100644
> index 0000000..9c8589c
> --- /dev/null
> +++ b/support/tst-support_format_dns_packet.c
> @@ -0,0 +1,101 @@
> +/* Tests for the support_format_dns_packet function.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/format_nss.h>
> +#include <support/run_diff.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +
> +static void
> +check_packet (const void *buffer, size_t length,
> +              const char *name, const char *expected)
> +{
> +  char *actual = support_format_dns_packet (buffer, length);
> +  if (strcmp (actual, expected) != 0)
> +    {
> +      support_record_failure ();
> +      printf ("error: formatted packet does not match: %s\n", name);
> +      support_run_diff ("expected", expected,
> +                        "actual", actual);
> +    }
> +  free (actual);
> +}
> +
> +static void
> +test_aaaa_length (void)
> +{
> +  static const char packet[] =
> +    /* Header: Response with two records.  */
> +    "\x12\x34\x80\x00\x00\x01\x00\x02\x00\x00\x00\x00"
> +    /* Question section.  www.example/IN/AAAA.  */
> +    "\x03www\x07""example\x00\x00\x1c\x00\x01"
> +    /* Answer section.  www.example AAAA [corrupted].  */
> +    "\xc0\x0c"
> +    "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x10"
> +    "\x20\x01\x0d\xb8\x05\x06\x07\x08"
> +    "\x11\x12\x13\x14\x15\x16\x17\x18"
> +    /* www.example AAAA [corrupted].  */
> +    "\xc0\x0c"
> +    "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x11"
> +    "\x01\x02\x03\x04\x05\x06\x07\x08"
> +    "\x11\x12\x13\x14\x15\x16\x17\x18" "\xff";
> +  check_packet (packet, sizeof (packet) - 1, __func__,
> +                "name: www.example\n"
> +                "address: 2001:db8:506:708:1112:1314:1516:1718\n"
> +                "error: AAAA record of size 17: www.example\n");
> +}
> +
> +static void
> +test_multiple_cnames (void)
> +{
> +  static const char packet[] =
> +    /* Header: Response with three records.  */
> +    "\x12\x34\x80\x00\x00\x01\x00\x03\x00\x00\x00\x00"
> +    /* Question section.  www.example/IN/A.  */
> +    "\x03www\x07""example\x00\x00\x01\x00\x01"
> +    /* Answer section.  www.example CNAME www1.example.  */
> +    "\xc0\x0c"
> +    "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07"
> +    "\x04www1\xc0\x10"
> +    /* www1 CNAME www2.  */
> +    "\x04www1\xc0\x10"
> +    "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07"
> +    "\x04www2\xc0\x10"
> +    /* www2 A 192.0.2.1.  */
> +    "\x04www2\xc0\x10"
> +    "\x00\x01\x00\x01\x00\x00\x00\x00\x00\x04"
> +    "\xc0\x00\x02\x01";
> +  check_packet (packet, sizeof (packet) - 1, __func__,
> +                "name: www.example\n"
> +                "name: www1.example\n"
> +                "name: www2.example\n"
> +                "address: 192.0.2.1\n");
> +}
> +
> +static int
> +do_test (void)
> +{
> +  test_aaaa_length ();
> +  test_multiple_cnames ();
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/support/tst-support_record_failure-2.sh b/support/tst-support_record_failure-2.sh
> new file mode 100644
> index 0000000..2c9372c
> --- /dev/null
> +++ b/support/tst-support_record_failure-2.sh
> @@ -0,0 +1,69 @@
> +#!/bin/sh
> +# Test failure recording (with and without --direct).
> +# Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +# This file is part of the GNU C Library.
> +
> +# The GNU C Library is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU Lesser General Public
> +# License as published by the Free Software Foundation; either
> +# version 2.1 of the License, or (at your option) any later version.
> +#
> +# The GNU C Library is distributed in the hope that it will be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +# Lesser General Public License for more details.
> +#
> +# You should have received a copy of the GNU Lesser General Public
> +# License along with the GNU C Library; if not, see
> +# <http://www.gnu.org/licenses/>.  */
> +
> +set -e
> +
> +common_objpfx=$1; shift
> +test_program_prefix_before_env=$1; shift
> +run_program_env=$1; shift
> +test_program_prefix_after_env=$1; shift
> +
> +run_test () {
> +    expected_status="$1"
> +    expected_output="$2"
> +    shift 2
> +    args="${common_objpfx}support/tst-support_record_failure $*"
> +    echo "running: $args"
> +    set +e
> +    output="$(${test_program_prefix_before_env} \
> +		 ${run_program} ${test_program_prefix_after_env} $args)"
> +    status=$?
> +    set -e
> +    echo "  exit status: $status"
> +    if test "$output" != "$expected_output" ; then
> +	echo "error: unexpected output: $output"
> +	exit 1
> +    fi
> +    if test "$status" -ne "$expected_status" ; then
> +	echo "error: exit status $expected_status expected"
> +	exit 1
> +    fi
> +}
> +
> +different_status () {
> +    direct="$1"
> +    run_test 1 "error: 1 test failures" $direct --status=0
> +    run_test 1 "error: 1 test failures" $direct --status=1
> +    run_test 2 "error: 1 test failures" $direct --status=2
> +    run_test 1 "error: 1 test failures" $direct --status=77
> +    run_test 2 "error: tst-support_record_failure.c:109: not true: false
> +error: 1 test failures" $direct --test-verify
> +    run_test 2 "error: tst-support_record_failure.c:109: not true: false
> +info: execution passed failed TEST_VERIFY
> +error: 1 test failures" $direct --test-verify --verbose
> +}
> +
> +different_status
> +different_status --direct
> +
> +run_test 1 "error: tst-support_record_failure.c:116: not true: false
> +error: 1 test failures" --test-verify-exit
> +# --direct does not print the summary error message if exit is called.
> +run_test 1 "error: tst-support_record_failure.c:116: not true: false" \
> +	 --direct --test-verify-exit
> diff --git a/support/tst-support_record_failure.c b/support/tst-support_record_failure.c
> new file mode 100644
> index 0000000..e739e73
> --- /dev/null
> +++ b/support/tst-support_record_failure.c
> @@ -0,0 +1,153 @@
> +/* Test support_record_failure state sharing.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/support.h>
> +#include <support/test-driver.h>
> +#include <support/xunistd.h>
> +
> +#include <getopt.h>
> +#include <stdbool.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +
> +static int exit_status_with_failure = -1;
> +static bool test_verify;
> +static bool test_verify_exit;
> +enum
> +  {
> +    OPT_STATUS = 10001,
> +    OPT_TEST_VERIFY,
> +    OPT_TEST_VERIFY_EXIT,
> +  };
> +#define CMDLINE_OPTIONS                                                 \
> +  { "status", required_argument, NULL, OPT_STATUS },                    \
> +  { "test-verify", no_argument, NULL, OPT_TEST_VERIFY },                \
> +  { "test-verify-exit", no_argument, NULL, OPT_TEST_VERIFY_EXIT },
> +static void
> +cmdline_process (int c)
> +{
> +  switch (c)
> +    {
> +    case OPT_STATUS:
> +      exit_status_with_failure = atoi (optarg);
> +      break;
> +    case OPT_TEST_VERIFY:
> +      test_verify = true;
> +      break;
> +    case OPT_TEST_VERIFY_EXIT:
> +      test_verify_exit = true;
> +      break;
> +    }
> +}
> +#define CMDLINE_PROCESS cmdline_process
> +
> +static void
> +check_failure_reporting (int phase, int zero, int unsupported)
> +{
> +  int status = support_report_failure (0);
> +  if (status != zero)
> +    {
> +      printf ("real-error (phase %d): support_report_failure (0) == %d\n",
> +              phase, status);
> +      exit (1);
> +    }
> +  status = support_report_failure (1);
> +  if (status != 1)
> +    {
> +      printf ("real-error (phase %d): support_report_failure (1) == %d\n",
> +              phase, status);
> +      exit (1);
> +    }
> +  status = support_report_failure (2);
> +  if (status != 2)
> +    {
> +      printf ("real-error (phase %d): support_report_failure (2) == %d\n",
> +              phase, status);
> +      exit (1);
> +    }
> +  status = support_report_failure (EXIT_UNSUPPORTED);
> +  if (status != unsupported)
> +    {
> +      printf ("real-error (phase %d): "
> +              "support_report_failure (EXIT_UNSUPPORTED) == %d\n",
> +              phase, status);
> +      exit (1);
> +    }
> +}
> +
> +static int
> +do_test (void)
> +{
> +  if (exit_status_with_failure >= 0)
> +    {
> +      /* External invocation with requested error status.  Used by
> +         tst-support_report_failure-2.sh.  */
> +      support_record_failure ();
> +      return exit_status_with_failure;
> +    }
> +  TEST_VERIFY (true);
> +  TEST_VERIFY_EXIT (true);
> +  if (test_verify)
> +    {
> +      TEST_VERIFY (false);
> +      if (test_verbose)
> +        printf ("info: execution passed failed TEST_VERIFY\n");
> +      return 2; /* Expected exit status.  */
> +    }
> +  if (test_verify_exit)
> +    {
> +      TEST_VERIFY_EXIT (false);
> +      return 3; /* Not reached.  Expected exit status is 1.  */
> +    }
> +
> +  printf ("info: This test tests the test framework.\n"
> +          "info: It reports some expected errors on stdout.\n");
> +
> +  /* Check that the status is passed through unchanged.  */
> +  check_failure_reporting (1, 0, EXIT_UNSUPPORTED);
> +
> +  /* Check state propagation from a subprocess.  */
> +  pid_t pid = xfork ();
> +  if (pid == 0)
> +    {
> +      support_record_failure ();
> +      _exit (0);
> +    }
> +  int status;
> +  xwaitpid (pid, &status, 0);
> +  if (status != 0)
> +    {
> +      printf ("real-error: incorrect status from subprocess: %d\n", status);
> +      return 1;
> +    }
> +  check_failure_reporting (2, 1, 1);
> +
> +  /* Also test directly in the parent process.  */
> +  support_record_failure_reset ();
> +  check_failure_reporting (3, 0, EXIT_UNSUPPORTED);
> +  support_record_failure ();
> +  check_failure_reporting (4, 1, 1);
> +
> +  /* We need to mask the failure above.  */
> +  support_record_failure_reset ();
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> diff --git a/support/write_message.c b/support/write_message.c
> new file mode 100644
> index 0000000..f03ed93
> --- /dev/null
> +++ b/support/write_message.c
> @@ -0,0 +1,29 @@
> +/* Write a message to standard output.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <string.h>
> +#include <unistd.h>
> +
> +void
> +write_message (const char *message)
> +{
> +  ssize_t unused __attribute__ ((unused));
> +  unused = write (STDOUT_FILENO, message, strlen (message));
> +}
> diff --git a/support/xaccept.c b/support/xaccept.c
> new file mode 100644
> index 0000000..7b25af3
> --- /dev/null
> +++ b/support/xaccept.c
> @@ -0,0 +1,32 @@
> +/* accept with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +int
> +xaccept (int fd, struct sockaddr *sa, socklen_t *salen)
> +{
> +  int clientfd = accept (fd, sa, salen);
> +  if (clientfd < 0)
> +    FAIL_EXIT1 ("accept (%d): %m", fd);
> +  return clientfd;
> +}
> diff --git a/support/xaccept4.c b/support/xaccept4.c
> new file mode 100644
> index 0000000..67dd95e
> --- /dev/null
> +++ b/support/xaccept4.c
> @@ -0,0 +1,32 @@
> +/* accept4 with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +int
> +xaccept4 (int fd, struct sockaddr *sa, socklen_t *salen, int flags)
> +{
> +  int clientfd = accept4 (fd, sa, salen, flags);
> +  if (clientfd < 0)
> +    FAIL_EXIT1 ("accept4 (%d, 0x%x): %m", fd, flags);
> +  return clientfd;
> +}
> diff --git a/support/xasprintf.c b/support/xasprintf.c
> new file mode 100644
> index 0000000..5157680
> --- /dev/null
> +++ b/support/xasprintf.c
> @@ -0,0 +1,36 @@
> +/* Error-checking wrapper for asprintf.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +char *
> +xasprintf (const char *format, ...)
> +{
> +  va_list ap;
> +  va_start (ap, format);
> +  char *result;
> +  if (vasprintf (&result, format, ap) < 0)
> +    FAIL_EXIT1 ("asprintf: %m");
> +  va_end (ap);
> +  return result;
> +}
> diff --git a/support/xbind.c b/support/xbind.c
> new file mode 100644
> index 0000000..cfc6dd8
> --- /dev/null
> +++ b/support/xbind.c
> @@ -0,0 +1,30 @@
> +/* bind with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xbind (int fd, const struct sockaddr *sa, socklen_t sa_len)
> +{
> +  if (bind (fd, sa, sa_len) != 0)
> +    FAIL_EXIT1 ("bind (%d), family %d: %m", fd, sa->sa_family);
> +}
> diff --git a/support/xcalloc.c b/support/xcalloc.c
> new file mode 100644
> index 0000000..135f42d
> --- /dev/null
> +++ b/support/xcalloc.c
> @@ -0,0 +1,34 @@
> +/* Error-checking wrapper for calloc.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void *
> +xcalloc (size_t n, size_t s)
> +{
> +  void *p;
> +
> +  p = calloc (n, s);
> +  if (p == NULL)
> +    oom_error ("calloc", n * s);
> +  return p;
> +}
> diff --git a/support/xchroot.c b/support/xchroot.c
> new file mode 100644
> index 0000000..abcc299
> --- /dev/null
> +++ b/support/xchroot.c
> @@ -0,0 +1,28 @@
> +/* chroot with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/stat.h>
> +
> +void
> +xchroot (const char *path)
> +{
> +  if (chroot (path) != 0)
> +    FAIL_EXIT1 ("chroot (\"%s\"): %m", path);
> +}
> diff --git a/support/xclose.c b/support/xclose.c
> new file mode 100644
> index 0000000..c931e08
> --- /dev/null
> +++ b/support/xclose.c
> @@ -0,0 +1,28 @@
> +/* close with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +#include <support/check.h>
> +#include <errno.h>
> +
> +void
> +xclose (int fd)
> +{
> +  if (close (fd) < 0 && errno != EINTR)
> +    FAIL_EXIT1 ("close of descriptor %d failed: %m", fd);
> +}
> diff --git a/support/xconnect.c b/support/xconnect.c
> new file mode 100644
> index 0000000..0266dbc
> --- /dev/null
> +++ b/support/xconnect.c
> @@ -0,0 +1,30 @@
> +/* connect with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xconnect (int fd, const struct sockaddr *sa, socklen_t sa_len)
> +{
> +  if (connect (fd, sa, sa_len) != 0)
> +    FAIL_EXIT1 ("connect (%d), family %d: %m", fd, sa->sa_family);
> +}
> diff --git a/support/xdup2.c b/support/xdup2.c
> new file mode 100644
> index 0000000..dc08c94
> --- /dev/null
> +++ b/support/xdup2.c
> @@ -0,0 +1,28 @@
> +/* dup2 with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +
> +#include <support/check.h>
> +
> +void
> +xdup2 (int from, int to)
> +{
> +  if (dup2 (from, to) < 0)
> +    FAIL_EXIT1 ("dup2 (%d, %d): %m", from, to);
> +}
> diff --git a/support/xfclose.c b/support/xfclose.c
> new file mode 100644
> index 0000000..2737f05
> --- /dev/null
> +++ b/support/xfclose.c
> @@ -0,0 +1,33 @@
> +/* fclose with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xstdio.h>
> +
> +#include <support/check.h>
> +#include <stdlib.h>
> +
> +void
> +xfclose (FILE *fp)
> +{
> +  if (ferror (fp))
> +    FAIL_EXIT1 ("stdio stream closed with pending errors");
> +  if (fflush (fp) != 0)
> +    FAIL_EXIT1 ("fflush: %m");
> +  if (fclose (fp) != 0)
> +    FAIL_EXIT1 ("fclose: %m");
> +}
> diff --git a/support/xfopen.c b/support/xfopen.c
> new file mode 100644
> index 0000000..14532a0
> --- /dev/null
> +++ b/support/xfopen.c
> @@ -0,0 +1,31 @@
> +/* fopen with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xstdio.h>
> +
> +#include <support/check.h>
> +#include <stdlib.h>
> +
> +FILE *
> +xfopen (const char *path, const char *mode)
> +{
> +  FILE *fp = fopen (path, mode);
> +  if (fp == NULL)
> +    FAIL_EXIT1 ("could not open %s (mode \"%s\"): %m", path, mode);
> +  return fp;
> +}
> diff --git a/support/xfork.c b/support/xfork.c
> new file mode 100644
> index 0000000..aa52ba6
> --- /dev/null
> +++ b/support/xfork.c
> @@ -0,0 +1,32 @@
> +/* fork with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +pid_t
> +xfork (void)
> +{
> +  pid_t result = fork ();
> +  if (result < 0)
> +    FAIL_EXIT1 ("fork: %m");
> +  return result;
> +}
> diff --git a/support/xgetsockname.c b/support/xgetsockname.c
> new file mode 100644
> index 0000000..c3bd884
> --- /dev/null
> +++ b/support/xgetsockname.c
> @@ -0,0 +1,30 @@
> +/* getsockname with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xgetsockname (int fd, struct sockaddr *sa, socklen_t *plen)
> +{
> +  if (getsockname (fd, sa, plen) != 0)
> +    FAIL_EXIT1 ("setsockopt (%d): %m", fd);
> +}
> diff --git a/support/xlisten.c b/support/xlisten.c
> new file mode 100644
> index 0000000..1953e59
> --- /dev/null
> +++ b/support/xlisten.c
> @@ -0,0 +1,30 @@
> +/* listen with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xlisten (int fd, int backlog)
> +{
> +  if (listen (fd, backlog) != 0)
> +    FAIL_EXIT1 ("listen (%d, %d): %m", fd, backlog);
> +}
> diff --git a/support/xmalloc.c b/support/xmalloc.c
> new file mode 100644
> index 0000000..450f699
> --- /dev/null
> +++ b/support/xmalloc.c
> @@ -0,0 +1,34 @@
> +/* Error-checking wrapper for malloc.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void *
> +xmalloc (size_t n)
> +{
> +  void *p;
> +
> +  p = malloc (n);
> +  if (p == NULL)
> +    oom_error ("malloc", n);
> +  return p;
> +}
> diff --git a/support/xmemstream.c b/support/xmemstream.c
> new file mode 100644
> index 0000000..bce6dc9
> --- /dev/null
> +++ b/support/xmemstream.c
> @@ -0,0 +1,42 @@
> +/* Error-checking wrappers for memstream functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xmemstream.h>
> +
> +#include <errno.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <support/xstdio.h>
> +
> +void
> +xopen_memstream (struct xmemstream *stream)
> +{
> +  int old_errno = errno;
> +  *stream = (struct xmemstream) {};
> +  stream->out = open_memstream (&stream->buffer, &stream->length);
> +  if (stream->out == NULL)
> +    FAIL_EXIT1 ("open_memstream: %m");
> +  errno = old_errno;
> +}
> +
> +void
> +xfclose_memstream (struct xmemstream *stream)
> +{
> +  xfclose (stream->out);
> +  stream->out = NULL;
> +}
> diff --git a/support/xmemstream.h b/support/xmemstream.h
> new file mode 100644
> index 0000000..e5ba231
> --- /dev/null
> +++ b/support/xmemstream.h
> @@ -0,0 +1,49 @@
> +/* Error-checking wrappers for memstream functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_XMEMSTREAM_H
> +#define SUPPORT_XMEMSTREAM_H
> +
> +#include <stdio.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Wrappers for other libc functions.  */
> +struct xmemstream
> +{
> +  FILE *out;
> +  char *buffer;
> +  size_t length;
> +};
> +
> +/* Create a new in-memory stream.  Initializes *STREAM.  After this
> +   function returns, STREAM->out is a file descriptor open for
> +   writing.  errno is preserved, so that the %m format specifier can
> +   be used for writing to STREAM->out.  */
> +void xopen_memstream (struct xmemstream *stream);
> +
> +/* Closes STREAM->OUT.  After this function returns, STREAM->buffer
> +   and STREAM->length denote a memory range which contains the bytes
> +   written to the output stream.  The caller should free
> +   STREAM->buffer.  */
> +void xfclose_memstream (struct xmemstream *stream);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_XMEMSTREAM_H */
> diff --git a/support/xmkdir.c b/support/xmkdir.c
> new file mode 100644
> index 0000000..ea17d49
> --- /dev/null
> +++ b/support/xmkdir.c
> @@ -0,0 +1,28 @@
> +/* mkdir with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/stat.h>
> +
> +void
> +xmkdir (const char *path, mode_t mode)
> +{
> +  if (mkdir (path, mode) != 0)
> +    FAIL_EXIT1 ("mkdir (\"%s\", 0%o): %m", path, mode);
> +}
> diff --git a/support/xmmap.c b/support/xmmap.c
> new file mode 100644
> index 0000000..435b1eb
> --- /dev/null
> +++ b/support/xmmap.c
> @@ -0,0 +1,31 @@
> +/* mmap with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/mman.h>
> +
> +void *
> +xmmap (void *addr, size_t length, int prot, int flags, int fd)
> +{
> +  void *result = mmap (addr, length, prot, flags, fd, 0);
> +  if (result == MAP_FAILED)
> +    FAIL_EXIT1 ("mmap of %zu bytes, prot=0x%x, flags=0x%x: %m",
> +                length, prot, flags);
> +  return result;
> +}
> diff --git a/support/xmunmap.c b/support/xmunmap.c
> new file mode 100644
> index 0000000..6ef5a4a
> --- /dev/null
> +++ b/support/xmunmap.c
> @@ -0,0 +1,28 @@
> +/* munmap with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <sys/mman.h>
> +
> +void
> +xmunmap (void *addr, size_t length)
> +{
> +  if (munmap (addr, length) != 0)
> +    FAIL_EXIT1 ("munmap of %zu bytes: %m", length);
> +}
> diff --git a/support/xopen.c b/support/xopen.c
> new file mode 100644
> index 0000000..7f033a0
> --- /dev/null
> +++ b/support/xopen.c
> @@ -0,0 +1,30 @@
> +/* open64 with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <fcntl.h>
> +
> +int
> +xopen (const char *path, int flags, mode_t mode)
> +{
> +  int ret = open64 (path, flags, mode);
> +  if (ret < 0)
> +    FAIL_EXIT1 ("open64 (\"%s\", 0x%x, 0%o): %m", path, flags, mode);
> +  return ret;
> +}
> diff --git a/support/xpipe.c b/support/xpipe.c
> new file mode 100644
> index 0000000..89a64a5
> --- /dev/null
> +++ b/support/xpipe.c
> @@ -0,0 +1,28 @@
> +/* pipe with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +
> +#include <support/check.h>
> +
> +void
> +xpipe (int fds[2])
> +{
> +  if (pipe (fds) < 0)
> +    FAIL_EXIT1 ("pipe: %m");
> +}
> diff --git a/support/xpoll.c b/support/xpoll.c
> new file mode 100644
> index 0000000..bec2521
> --- /dev/null
> +++ b/support/xpoll.c
> @@ -0,0 +1,32 @@
> +/* poll with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +int
> +xpoll (struct pollfd *fds, nfds_t nfds, int timeout)
> +{
> +  int ret = poll (fds, nfds, timeout);
> +  if (ret < 0)
> +    FAIL_EXIT1 ("poll: %m");
> +  return ret;
> +}
> diff --git a/support/xpthread_attr_destroy.c b/support/xpthread_attr_destroy.c
> new file mode 100644
> index 0000000..664c809
> --- /dev/null
> +++ b/support/xpthread_attr_destroy.c
> @@ -0,0 +1,26 @@
> +/* pthread_attr_destroy with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_attr_destroy (pthread_attr_t *attr)
> +{
> +  xpthread_check_return ("pthread_attr_destroy",
> +			 pthread_attr_destroy (attr));
> +}
> diff --git a/support/xpthread_attr_init.c b/support/xpthread_attr_init.c
> new file mode 100644
> index 0000000..2e30ade
> --- /dev/null
> +++ b/support/xpthread_attr_init.c
> @@ -0,0 +1,25 @@
> +/* pthread_attr_init with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_attr_init (pthread_attr_t *attr)
> +{
> +  xpthread_check_return ("pthread_attr_init", pthread_attr_init (attr));
> +}
> diff --git a/support/xpthread_attr_setdetachstate.c b/support/xpthread_attr_setdetachstate.c
> new file mode 100644
> index 0000000..b544dba
> --- /dev/null
> +++ b/support/xpthread_attr_setdetachstate.c
> @@ -0,0 +1,27 @@
> +/* pthread_attr_setdetachstate with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_attr_setdetachstate (pthread_attr_t *attr, int detachstate)
> +{
> +  xpthread_check_return ("pthread_attr_setdetachstate",
> +			 pthread_attr_setdetachstate (attr,
> +						      detachstate));
> +}
> diff --git a/support/xpthread_attr_setstacksize.c b/support/xpthread_attr_setstacksize.c
> new file mode 100644
> index 0000000..02d0631
> --- /dev/null
> +++ b/support/xpthread_attr_setstacksize.c
> @@ -0,0 +1,26 @@
> +/* pthread_attr_setstacksize with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_attr_setstacksize (pthread_attr_t *attr, size_t stacksize)
> +{
> +  xpthread_check_return ("pthread_attr_setstacksize",
> +			 pthread_attr_setstacksize (attr, stacksize));
> +}
> diff --git a/support/xpthread_barrier_destroy.c b/support/xpthread_barrier_destroy.c
> new file mode 100644
> index 0000000..efc0719
> --- /dev/null
> +++ b/support/xpthread_barrier_destroy.c
> @@ -0,0 +1,26 @@
> +/* pthread_barrier_destroy with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_barrier_destroy (pthread_barrier_t *barrier)
> +{
> +  xpthread_check_return ("pthread_barrier_destroy",
> +                         pthread_barrier_destroy (barrier));
> +}
> diff --git a/support/xpthread_barrier_init.c b/support/xpthread_barrier_init.c
> new file mode 100644
> index 0000000..b32dad1
> --- /dev/null
> +++ b/support/xpthread_barrier_init.c
> @@ -0,0 +1,27 @@
> +/* pthread_barrier_init with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_barrier_init (pthread_barrier_t *barrier,
> +                       pthread_barrierattr_t *attr, unsigned int count)
> +{
> +  xpthread_check_return ("pthread_barrier_init",
> +                         pthread_barrier_init (barrier, attr, count));
> +}
> diff --git a/support/xpthread_barrier_wait.c b/support/xpthread_barrier_wait.c
> new file mode 100644
> index 0000000..7cee44d
> --- /dev/null
> +++ b/support/xpthread_barrier_wait.c
> @@ -0,0 +1,28 @@
> +/* pthread_barrier_wait with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +int
> +xpthread_barrier_wait (pthread_barrier_t *barrier)
> +{
> +  int ret = pthread_barrier_wait (barrier);
> +  if (ret != 0 && ret != PTHREAD_BARRIER_SERIAL_THREAD)
> +    xpthread_check_return ("pthread_barrier_wait", ret);
> +  return ret == PTHREAD_BARRIER_SERIAL_THREAD;
> +}
> diff --git a/support/xpthread_cancel.c b/support/xpthread_cancel.c
> new file mode 100644
> index 0000000..3af16f9
> --- /dev/null
> +++ b/support/xpthread_cancel.c
> @@ -0,0 +1,25 @@
> +/* pthread_cancel with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_cancel (pthread_t thr)
> +{
> +  xpthread_check_return ("pthread_cancel", pthread_cancel (thr));
> +}
> diff --git a/support/xpthread_check_return.c b/support/xpthread_check_return.c
> new file mode 100644
> index 0000000..3094d82
> --- /dev/null
> +++ b/support/xpthread_check_return.c
> @@ -0,0 +1,34 @@
> +/* Return value checking for pthread functions, exit variant.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +#include <errno.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xpthread_check_return (const char *function, int value)
> +{
> +  if (value != 0)
> +    {
> +      errno = value;
> +      FAIL_EXIT1 ("%s: %m", function);
> +    }
> +}
> diff --git a/support/xpthread_cond_wait.c b/support/xpthread_cond_wait.c
> new file mode 100644
> index 0000000..b0e9b2a
> --- /dev/null
> +++ b/support/xpthread_cond_wait.c
> @@ -0,0 +1,26 @@
> +/* pthread_cond_wait with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
> +{
> +  xpthread_check_return
> +    ("pthread_cond_wait", pthread_cond_wait (cond, mutex));
> +}
> diff --git a/support/xpthread_create.c b/support/xpthread_create.c
> new file mode 100644
> index 0000000..98c63e5
> --- /dev/null
> +++ b/support/xpthread_create.c
> @@ -0,0 +1,29 @@
> +/* pthread_create with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +pthread_t
> +xpthread_create (pthread_attr_t *attr,
> +                 void *(*thread_func) (void *), void *closure)
> +{
> +  pthread_t thr;
> +  xpthread_check_return
> +    ("pthread_create", pthread_create (&thr, attr, thread_func, closure));
> +  return thr;
> +}
> diff --git a/support/xpthread_detach.c b/support/xpthread_detach.c
> new file mode 100644
> index 0000000..2088af2
> --- /dev/null
> +++ b/support/xpthread_detach.c
> @@ -0,0 +1,25 @@
> +/* pthread_detach with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_detach (pthread_t thr)
> +{
> +  xpthread_check_return ("pthread_detach", pthread_detach (thr));
> +}
> diff --git a/support/xpthread_join.c b/support/xpthread_join.c
> new file mode 100644
> index 0000000..f23bb9a
> --- /dev/null
> +++ b/support/xpthread_join.c
> @@ -0,0 +1,27 @@
> +/* pthread_join with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void *
> +xpthread_join (pthread_t thr)
> +{
> +  void *result;
> +  xpthread_check_return ("pthread_join", pthread_join (thr, &result));
> +  return result;
> +}
> diff --git a/support/xpthread_mutex_consistent.c b/support/xpthread_mutex_consistent.c
> new file mode 100644
> index 0000000..52364be
> --- /dev/null
> +++ b/support/xpthread_mutex_consistent.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutex_consistent with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutex_consistent (pthread_mutex_t *mutex)
> +{
> +  xpthread_check_return ("pthread_mutex_consistent",
> +                         pthread_mutex_consistent (mutex));
> +}
> diff --git a/support/xpthread_mutex_destroy.c b/support/xpthread_mutex_destroy.c
> new file mode 100644
> index 0000000..f11f8f0
> --- /dev/null
> +++ b/support/xpthread_mutex_destroy.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutex_destroy with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutex_destroy (pthread_mutex_t *mutex)
> +{
> +  xpthread_check_return ("pthread_mutex_destroy",
> +                         pthread_mutex_destroy (mutex));
> +}
> diff --git a/support/xpthread_mutex_init.c b/support/xpthread_mutex_init.c
> new file mode 100644
> index 0000000..2d16d1b
> --- /dev/null
> +++ b/support/xpthread_mutex_init.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutex_init with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutex_init (pthread_mutex_t *mutex, const pthread_mutexattr_t *attr)
> +{
> +  xpthread_check_return ("pthread_mutex_init",
> +                         pthread_mutex_init (mutex, attr));
> +}
> diff --git a/support/xpthread_mutex_lock.c b/support/xpthread_mutex_lock.c
> new file mode 100644
> index 0000000..af727b4
> --- /dev/null
> +++ b/support/xpthread_mutex_lock.c
> @@ -0,0 +1,25 @@
> +/* pthread_mutex_lock with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutex_lock (pthread_mutex_t *mutex)
> +{
> +  xpthread_check_return ("pthread_mutex_lock", pthread_mutex_lock (mutex));
> +}
> diff --git a/support/xpthread_mutex_unlock.c b/support/xpthread_mutex_unlock.c
> new file mode 100644
> index 0000000..161b41e
> --- /dev/null
> +++ b/support/xpthread_mutex_unlock.c
> @@ -0,0 +1,25 @@
> +/* pthread_mutex_unlock with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutex_unlock (pthread_mutex_t *mutex)
> +{
> +  xpthread_check_return ("pthread_mutex_unlock", pthread_mutex_unlock (mutex));
> +}
> diff --git a/support/xpthread_mutexattr_destroy.c b/support/xpthread_mutexattr_destroy.c
> new file mode 100644
> index 0000000..c699e32
> --- /dev/null
> +++ b/support/xpthread_mutexattr_destroy.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutexattr_destroy with error checking.
> +   Copyright (C) 2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_destroy (pthread_mutexattr_t *attr)
> +{
> +  xpthread_check_return ("pthread_mutexattr_destroy",
> +                         pthread_mutexattr_destroy (attr));
> +}
> diff --git a/support/xpthread_mutexattr_init.c b/support/xpthread_mutexattr_init.c
> new file mode 100644
> index 0000000..fa93fab
> --- /dev/null
> +++ b/support/xpthread_mutexattr_init.c
> @@ -0,0 +1,25 @@
> +/* pthread_mutexattr_init with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_init (pthread_mutexattr_t *attr)
> +{
> +  xpthread_check_return ("pthread_mutexattr_init", pthread_mutexattr_init (attr));
> +}
> diff --git a/support/xpthread_mutexattr_setprotocol.c b/support/xpthread_mutexattr_setprotocol.c
> new file mode 100644
> index 0000000..353f75e
> --- /dev/null
> +++ b/support/xpthread_mutexattr_setprotocol.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutexattr_setprotocol with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_setprotocol (pthread_mutexattr_t *attr, int flag)
> +{
> +  xpthread_check_return ("pthread_mutexattr_setprotocol",
> +                         pthread_mutexattr_setprotocol (attr, flag));
> +}
> diff --git a/support/xpthread_mutexattr_setpshared.c b/support/xpthread_mutexattr_setpshared.c
> new file mode 100644
> index 0000000..242da1a
> --- /dev/null
> +++ b/support/xpthread_mutexattr_setpshared.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutexattr_setpshared with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_setpshared (pthread_mutexattr_t *attr, int flag)
> +{
> +  xpthread_check_return ("pthread_mutexattr_setpshared",
> +                         pthread_mutexattr_setpshared (attr, flag));
> +}
> diff --git a/support/xpthread_mutexattr_setrobust.c b/support/xpthread_mutexattr_setrobust.c
> new file mode 100644
> index 0000000..d7d6fa8
> --- /dev/null
> +++ b/support/xpthread_mutexattr_setrobust.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutexattr_setrobust with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_setrobust (pthread_mutexattr_t *attr, int flag)
> +{
> +  xpthread_check_return ("pthread_mutexattr_setrobust",
> +                         pthread_mutexattr_setrobust (attr, flag));
> +}
> diff --git a/support/xpthread_mutexattr_settype.c b/support/xpthread_mutexattr_settype.c
> new file mode 100644
> index 0000000..cf22170
> --- /dev/null
> +++ b/support/xpthread_mutexattr_settype.c
> @@ -0,0 +1,26 @@
> +/* pthread_mutexattr_settype with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_mutexattr_settype (pthread_mutexattr_t *attr, int flag)
> +{
> +  xpthread_check_return ("pthread_mutexattr_settype",
> +                         pthread_mutexattr_settype (attr, flag));
> +}
> diff --git a/support/xpthread_once.c b/support/xpthread_once.c
> new file mode 100644
> index 0000000..70d58db
> --- /dev/null
> +++ b/support/xpthread_once.c
> @@ -0,0 +1,25 @@
> +/* pthread_once with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_once (pthread_once_t *guard, void (*func) (void))
> +{
> +  xpthread_check_return ("pthread_once", pthread_once (guard, func));
> +}
> diff --git a/support/xpthread_sigmask.c b/support/xpthread_sigmask.c
> new file mode 100644
> index 0000000..0ba9ca0
> --- /dev/null
> +++ b/support/xpthread_sigmask.c
> @@ -0,0 +1,34 @@
> +/* pthread_sigmask with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsignal.h>
> +#include <support/support.h>
> +
> +#include <unistd.h>
> +
> +void
> +xpthread_sigmask (int how, const sigset_t *set, sigset_t *oldset)
> +{
> +  if (pthread_sigmask (how, set, oldset) != 0)
> +    {
> +      write_message ("error: pthread_setmask failed\n");
> +      /* Do not use exit because pthread_sigmask can be called from a
> +         signal handler.  */
> +      _exit (1);
> +    }
> +}
> diff --git a/support/xpthread_spin_lock.c b/support/xpthread_spin_lock.c
> new file mode 100644
> index 0000000..6975215
> --- /dev/null
> +++ b/support/xpthread_spin_lock.c
> @@ -0,0 +1,25 @@
> +/* pthread_spin_lock with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_spin_lock (pthread_spinlock_t *lock)
> +{
> +  xpthread_check_return ("pthread_spin_lock", pthread_spin_lock (lock));
> +}
> diff --git a/support/xpthread_spin_unlock.c b/support/xpthread_spin_unlock.c
> new file mode 100644
> index 0000000..4f19a44
> --- /dev/null
> +++ b/support/xpthread_spin_unlock.c
> @@ -0,0 +1,25 @@
> +/* pthread_spin_unlock with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xthread.h>
> +
> +void
> +xpthread_spin_unlock (pthread_spinlock_t *lock)
> +{
> +  xpthread_check_return ("pthread_spin_unlock", pthread_spin_unlock (lock));
> +}
> diff --git a/support/xrealloc.c b/support/xrealloc.c
> new file mode 100644
> index 0000000..00c3138
> --- /dev/null
> +++ b/support/xrealloc.c
> @@ -0,0 +1,32 @@
> +/* Error-checking wrapper for realloc.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <stdarg.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +
> +void *
> +xrealloc (void *p, size_t n)
> +{
> +  void *result = realloc (p, n);
> +  if (result == NULL && (n > 0 || p == NULL))
> +    oom_error ("realloc", n);
> +  return result;
> +}
> diff --git a/support/xrecvfrom.c b/support/xrecvfrom.c
> new file mode 100644
> index 0000000..17809c4
> --- /dev/null
> +++ b/support/xrecvfrom.c
> @@ -0,0 +1,33 @@
> +/* recvfrom with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +size_t
> +xrecvfrom (int fd, void *buf, size_t buflen, int flags,
> +           struct sockaddr *sa, socklen_t *salen)
> +{
> +  ssize_t ret = recvfrom (fd, buf, buflen, flags, sa, salen);
> +  if (ret < 0)
> +    FAIL_EXIT1 ("error: recvfrom (%d), %zu bytes buffer: %m", fd, buflen);
> +  return ret;
> +}
> diff --git a/support/xsendto.c b/support/xsendto.c
> new file mode 100644
> index 0000000..20bddf6
> --- /dev/null
> +++ b/support/xsendto.c
> @@ -0,0 +1,35 @@
> +/* sendto with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xsendto (int fd, const void *buf, size_t buflen, int flags,
> +         const struct sockaddr *sa, socklen_t salen)
> +{
> +  ssize_t ret = sendto (fd, buf, buflen, flags, sa, salen);
> +  if (ret < 0)
> +    FAIL_EXIT1 ("sendto (%d), %zu bytes, family %d: %m",
> +                fd, buflen, sa->sa_family);
> +  if (ret != buflen)
> +    FAIL_EXIT1 ("sendto (%d) sent %zd bytes instead of %zu", fd, ret, buflen);
> +}
> diff --git a/support/xsetsockopt.c b/support/xsetsockopt.c
> new file mode 100644
> index 0000000..9931882
> --- /dev/null
> +++ b/support/xsetsockopt.c
> @@ -0,0 +1,31 @@
> +/* setsockopt with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +void
> +xsetsockopt (int fd, int level, int name, const void *val, socklen_t vallen)
> +{
> +  if (setsockopt (fd, level, name, val, vallen) != 0)
> +    FAIL_EXIT1 ("setsockopt (%d, %d, %d), %zu bytes: %m",
> +                fd, level, name, (size_t) vallen);
> +}
> diff --git a/support/xsignal.h b/support/xsignal.h
> new file mode 100644
> index 0000000..3dc0d9d
> --- /dev/null
> +++ b/support/xsignal.h
> @@ -0,0 +1,34 @@
> +/* Support functionality for using signals.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_SIGNAL_H
> +#define SUPPORT_SIGNAL_H
> +
> +#include <signal.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* The following functions call the corresponding libpthread functions
> +   and terminate the process on error.  */
> +
> +void xpthread_sigmask (int how, const sigset_t *set, sigset_t *oldset);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_SIGNAL_H */
> diff --git a/support/xsocket.c b/support/xsocket.c
> new file mode 100644
> index 0000000..c1deaee
> --- /dev/null
> +++ b/support/xsocket.c
> @@ -0,0 +1,32 @@
> +/* socket with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xsocket.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +
> +int
> +xsocket (int domain, int type, int protocol)
> +{
> +  int fd = socket (domain, type, protocol);
> +  if (fd < 0)
> +    FAIL_EXIT1 ("socket (%d, %d, %d): %m\n", domain, type, protocol);
> +  return fd;
> +}
> diff --git a/support/xsocket.h b/support/xsocket.h
> new file mode 100644
> index 0000000..d672494
> --- /dev/null
> +++ b/support/xsocket.h
> @@ -0,0 +1,39 @@
> +/* Error-checking wrappers for socket functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_XSOCKET_H
> +#define SUPPORT_XSOCKET_H
> +
> +#include <poll.h>
> +#include <sys/socket.h>
> +#include <sys/types.h>
> +
> +int xsocket (int, int, int);
> +void xsetsockopt (int, int, int, const void *, socklen_t);
> +void xgetsockname (int, struct sockaddr *, socklen_t *);
> +void xconnect (int, const struct sockaddr *, socklen_t);
> +void xbind (int, const struct sockaddr *, socklen_t);
> +void xlisten (int, int);
> +int xaccept (int, struct sockaddr *, socklen_t *);
> +int xaccept4 (int, struct sockaddr *, socklen_t *, int);
> +void xsendto (int, const void *, size_t, int,
> +              const struct sockaddr *, socklen_t);
> +size_t xrecvfrom (int, void *, size_t, int, struct sockaddr *, socklen_t *);
> +int xpoll (struct pollfd *, nfds_t, int);
> +
> +#endif /* SUPPORT_XSOCKET_H */
> diff --git a/support/xstdio.h b/support/xstdio.h
> new file mode 100644
> index 0000000..bcc2e86
> --- /dev/null
> +++ b/support/xstdio.h
> @@ -0,0 +1,32 @@
> +/* Error-checking wrappers for stdio functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_XSTDIO_H
> +#define SUPPORT_XSTDIO_H
> +
> +#include <stdio.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +FILE *xfopen (const char *path, const char *mode);
> +void xfclose (FILE *);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_XSTDIO_H */
> diff --git a/support/xstrdup.c b/support/xstrdup.c
> new file mode 100644
> index 0000000..d6a8c04
> --- /dev/null
> +++ b/support/xstrdup.c
> @@ -0,0 +1,30 @@
> +/* strdup with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/support.h>
> +
> +#include <string.h>
> +
> +char *
> +xstrdup (const char *s)
> +{
> +  char *p = strdup (s);
> +  if (p == NULL)
> +    oom_error ("strdup", strlen (s));
> +  return p;
> +}
> diff --git a/support/xthread.h b/support/xthread.h
> new file mode 100644
> index 0000000..6dd7e70
> --- /dev/null
> +++ b/support/xthread.h
> @@ -0,0 +1,77 @@
> +/* Support functionality for using threads.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#ifndef SUPPORT_THREAD_H
> +#define SUPPORT_THREAD_H
> +
> +#include <pthread.h>
> +#include <sys/cdefs.h>
> +
> +__BEGIN_DECLS
> +
> +/* Terminate the process (with exit status 0) after SECONDS have
> +   elapsed, from a helper thread.  The process is terminated with the
> +   exit function, so atexit handlers are executed.  */
> +void delayed_exit (int seconds);
> +
> +/* Terminate the process (with exit status 1) if VALUE is not zero.
> +   In that case, print a failure message to standard output mentioning
> +   FUNCTION.  The process is terminated with the exit function, so
> +   atexit handlers are executed.  */
> +void xpthread_check_return (const char *function, int value);
> +
> +/* The following functions call the corresponding libpthread functions
> +   and terminate the process on error.  */
> +
> +void xpthread_barrier_init (pthread_barrier_t *barrier,
> +                            pthread_barrierattr_t *attr, unsigned int count);
> +void xpthread_barrier_destroy (pthread_barrier_t *barrier);
> +void xpthread_mutexattr_destroy (pthread_mutexattr_t *);
> +void xpthread_mutexattr_init (pthread_mutexattr_t *);
> +void xpthread_mutexattr_setprotocol (pthread_mutexattr_t *, int);
> +void xpthread_mutexattr_setpshared (pthread_mutexattr_t *, int);
> +void xpthread_mutexattr_setrobust (pthread_mutexattr_t *, int);
> +void xpthread_mutexattr_settype (pthread_mutexattr_t *, int);
> +void xpthread_mutex_init (pthread_mutex_t *, const pthread_mutexattr_t *);
> +void xpthread_mutex_destroy (pthread_mutex_t *);
> +void xpthread_mutex_lock (pthread_mutex_t *mutex);
> +void xpthread_mutex_unlock (pthread_mutex_t *mutex);
> +void xpthread_mutex_consistent (pthread_mutex_t *);
> +void xpthread_spin_lock (pthread_spinlock_t *lock);
> +void xpthread_spin_unlock (pthread_spinlock_t *lock);
> +void xpthread_cond_wait (pthread_cond_t * cond, pthread_mutex_t * mutex);
> +pthread_t xpthread_create (pthread_attr_t *attr,
> +                           void *(*thread_func) (void *), void *closure);
> +void xpthread_detach (pthread_t thr);
> +void xpthread_cancel (pthread_t thr);
> +void *xpthread_join (pthread_t thr);
> +void xpthread_once (pthread_once_t *guard, void (*func) (void));
> +void xpthread_attr_destroy (pthread_attr_t *attr);
> +void xpthread_attr_init (pthread_attr_t *attr);
> +void xpthread_attr_setdetachstate (pthread_attr_t *attr,
> +				   int detachstate);
> +void xpthread_attr_setstacksize (pthread_attr_t *attr,
> +				 size_t stacksize);
> +
> +/* This function returns non-zero if pthread_barrier_wait returned
> +   PTHREAD_BARRIER_SERIAL_THREAD.  */
> +int xpthread_barrier_wait (pthread_barrier_t *barrier);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_THREAD_H */
> diff --git a/support/xunistd.h b/support/xunistd.h
> new file mode 100644
> index 0000000..151d743
> --- /dev/null
> +++ b/support/xunistd.h
> @@ -0,0 +1,56 @@
> +/* POSIX-specific extra functions.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +/* These wrapper functions use POSIX types and therefore cannot be
> +   declared in <support/support.h>.  */
> +
> +#ifndef SUPPORT_XUNISTD_H
> +#define SUPPORT_XUNISTD_H
> +
> +#include <sys/cdefs.h>
> +#include <sys/types.h>
> +#include <unistd.h>
> +
> +__BEGIN_DECLS
> +
> +struct stat64;
> +
> +pid_t xfork (void);
> +pid_t xwaitpid (pid_t, int *status, int flags);
> +void xpipe (int[2]);
> +void xdup2 (int, int);
> +int xopen (const char *path, int flags, mode_t);
> +void xstat (const char *path, struct stat64 *);
> +void xmkdir (const char *path, mode_t);
> +void xchroot (const char *path);
> +
> +/* Close the file descriptor.  Ignore EINTR errors, but terminate the
> +   process on other errors.  */
> +void xclose (int);
> +
> +/* Write the buffer.  Retry on short writes.  */
> +void xwrite (int, const void *, size_t);
> +
> +/* Invoke mmap with a zero file offset.  */
> +void *xmmap (void *addr, size_t length, int prot, int flags, int fd);
> +
> +void xmunmap (void *addr, size_t length);
> +
> +__END_DECLS
> +
> +#endif /* SUPPORT_XUNISTD_H */
> diff --git a/support/xwaitpid.c b/support/xwaitpid.c
> new file mode 100644
> index 0000000..204795e
> --- /dev/null
> +++ b/support/xwaitpid.c
> @@ -0,0 +1,33 @@
> +/* waitpid with error checking.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <support/check.h>
> +#include <sys/wait.h>
> +
> +int
> +xwaitpid (int pid, int *status, int flags)
> +{
> +  pid_t result = waitpid (pid, status, flags);
> +  if (result < 0)
> +    FAIL_EXIT1 ("waitpid: %m\n");
> +  return result;
> +}
> diff --git a/support/xwrite.c b/support/xwrite.c
> new file mode 100644
> index 0000000..134e8ee
> --- /dev/null
> +++ b/support/xwrite.c
> @@ -0,0 +1,39 @@
> +/* write with error checking and retries.
> +   Copyright (C) 2016-2017 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <support/xunistd.h>
> +
> +#include <support/check.h>
> +
> +void
> +xwrite (int fd, const void *buffer, size_t length)
> +{
> +  const char *p = buffer;
> +  const char *end = p + length;
> +  while (p < end)
> +    {
> +      ssize_t ret = write (fd, p, end - p);
> +      if (ret < 0)
> +        FAIL_EXIT1 ("write of %zu bytes failed after %td: %m",
> +                    length, p - (const char *) buffer);
> +      if (ret == 0)
> +        FAIL_EXIT1 ("write return 0 after writing %td bytes of %zu",
> +                    p - (const char *) buffer, length);
> +      p += ret;
> +    }
> +}
> 


-- 
Cheers,
Carlos.