[PATCH v2] Detect ld.so and libc.so version inconsistency during startup
Carlos O'Donell
carlos@redhat.com
Tue Aug 23 21:26:51 GMT 2022
On 8/23/22 13:36, Florian Weimer wrote:
> The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h
> contribute to the version fingerprint used for detection. The
> fingerprint can be further refined using the --with-extra-version-id
> configure argument.
OK.
Passes i686 pre-commit CI.
Passes my x86_64 testers.
Passes the smoke tests I used to verify the check detects wrong ld.so/libc mismatches.
I can't see this causes serious problems crossing container, chroot or namespace
boundaries because we load libc.so.6 early before doing any kind of transition.
Where it might have impact is in the developer workflow and we can adjust as
required.
Please post v3 with two comment typos fixed. I'll ACK v3.
The refactor and move to the early version check was a good solution!
Tested-by: Carlos O'Donell <carlos@redhat.com>
> _dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init.
> The new function is used store a pointer to libc.so's
> __libc_early_init function in the libc_map_early_init member of the
> ld.so namespace structure. This function pointer can then be called
> directly, so the separate invocation function is no longer needed.
>
> The versioned symbol lookup needs the symbol versioning data
> structures, so the initialization of libc_map and libc_map_early_init
> is now done from _dl_check_map_versions, after this information
> becomes available. (_dl_map_object_from_fd does not set this up
> in time, so the initialization code had to be moved from there.)
> This means that the separate initialization code can be removed from
> dl_main because _dl_check_map_versions covers all maps, including
> the initial executable loaded by the kernel. The lookup still happens
> before relocation and the invocation of IFUNC resolvers, so IFUNC
> resolvers are protected from ABI mismatch.
>
> The __libc_early_init function pointer is not protected because
> so little code runs between the pointer write and the invocation
> (only dynamic linker code and IFUNC resolvers).
>
> ---
> v2: Really quite different. I moved the __libc_early_init lookup before
> relocation processing, which had a bunch of knock-on effects.
> Re-tested on i386-linux-gnu and x86_64-linux-gnu.
> build-many-glibcs.py is still running.
> INSTALL | 10 +++
> Makerules | 14 ++++
> NEWS | 7 +-
> config.make.in | 1 +
> configure | 11 +++
> configure.ac | 5 ++
> elf/Makefile | 2 +-
> elf/Versions | 4 +-
> elf/dl-load.c | 9 ---
> ...bc-early-init.c => dl-lookup_libc_early_init.c} | 23 +++---
> elf/dl-open.c | 4 +-
> elf/dl-version.c | 18 +++++
> elf/libc-early-init.h | 21 ++++--
> elf/rtld.c | 12 +--
> manual/install.texi | 9 +++
> scripts/libc_early_init_name.py | 85 ++++++++++++++++++++++
> sysdeps/generic/ldsodefs.h | 4 +
> 17 files changed, 194 insertions(+), 45 deletions(-)
>
> diff --git a/INSTALL b/INSTALL
> index 659f75a97f..6470cd3d25 100644
> --- a/INSTALL
> +++ b/INSTALL
> @@ -120,6 +120,16 @@ if 'CFLAGS' is specified it must enable optimization. For example:
> compiler flags which target a later instruction set architecture
> (ISA).
>
> +'--with-extra-version-id=STRING'
> + Use STRING as part of the fingerprint that is used by the dynamic
> + linker to detect an incompatible version of 'libc.so'. For
> + example, STRING could be the full package version and release
> + string used by a distribution build of the GNU C Library. This
> + way, concurrent process creation during a package update will fail
> + with an error message, _error while loading shared libraries:
> + /lib64/libc.so.6: ld.so/libc.so mismatch detected (upgrade in
> + progress?)_, rather than crashing mysteriously.
OK. Regenerated.
> +
> '--with-timeoutfactor=NUM'
> Specify an integer NUM to scale the timeout of test programs. This
> factor can be changed at run time using 'TIMEOUTFACTOR' environment
> diff --git a/Makerules b/Makerules
> index d1e139d03c..756c1f181c 100644
> --- a/Makerules
> +++ b/Makerules
> @@ -112,6 +112,20 @@ before-compile := $(common-objpfx)first-versions.h \
> $(common-objpfx)ldbl-compat-choose.h $(before-compile)
> $(common-objpfx)first-versions.h: $(common-objpfx)versions.stmp
> $(common-objpfx)ldbl-compat-choose.h: $(common-objpfx)versions.stmp
> +
> +# libc_early_init_name.h provides the actual name of the
> +# __libc_early_init function. It is used as a protocol version marker
> +# between ld.so and libc.so
OK.
> +before-compile := $(common-objpfx)libc_early_init_name.h $(before-compile)
> +libc_early_init_name-deps = \
> + $(..)NEWS $(..)sysdeps/generic/ldsodefs.h $(..)include/link.h
> +$(common-objpfx)libc_early_init_name.h: $(..)scripts/libc_early_init_name.py \
> + $(common-objpfx)config.make $(libc_early_init_name-deps)
> + $(PYTHON) $(..)scripts/libc_early_init_name.py \
> + --output=$@T \
> + --extra-version-id="$(extra-version-id)" \
> + $(libc_early_init_name-deps)
OK.
> + $(move-if-change) $@T $@
> endif # avoid-generated
> endif # $(build-shared) = yes
>
> diff --git a/NEWS b/NEWS
> index f9bef48a8f..193c10e647 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -9,7 +9,12 @@ Version 2.37
>
> Major new features:
>
> - [Add new features here]
> +* The dynamic loader now prints an error message, "ld.so/libc.so
> + mismatch detected (upgrade in progress?)" if it detects that the
> + version of libc.so it loaded comes from a different build of glibc.
> + The new configure option --with-extra-version-id can be used to
> + specify an arbitrary string that affects the comptuation of the
s/comptuation/computation/g
> + version fingerprint.
>
> Deprecated and removed features, and other changes affecting compatibility:
>
> diff --git a/config.make.in b/config.make.in
> index d7c416cbea..ecaffbfd4b 100644
> --- a/config.make.in
> +++ b/config.make.in
> @@ -98,6 +98,7 @@ build-hardcoded-path-in-tests= @hardcoded_path_in_tests@
> build-pt-chown = @build_pt_chown@
> have-tunables = @have_tunables@
> pthread-in-libc = @pthread_in_libc@
> +extra-version-id = @extra_version_id@
OK.
>
> # Build tools.
> CC = @CC@
> diff --git a/configure b/configure
> index ff2c406b3b..c576f9f133 100755
> --- a/configure
> +++ b/configure
> @@ -760,6 +760,7 @@ with_headers
> with_default_link
> with_nonshared_cflags
> with_rtld_early_cflags
> +with_extra_version_id
> with_timeoutfactor
> enable_sanity_checks
> enable_shared
> @@ -1481,6 +1482,9 @@ Optional Packages:
> build nonshared libraries with additional CFLAGS
> --with-rtld-early-cflags=CFLAGS
> build early initialization with additional CFLAGS
> + --extra-version-id=STRING
> + specify an extra version string to use in internal
> + ABI checks
OK. Regenerated.
> --with-timeoutfactor=NUM
> specify an integer to scale the timeout
> --with-cpu=CPU select code for CPU variant
> @@ -3397,6 +3401,13 @@ fi
>
>
>
> +# Check whether --with-extra-version-id was given.
> +if test "${with_extra_version_id+set}" = set; then :
> + withval=$with_extra_version_id; extra_version_id="$withval"
> +fi
> +
> +
> +
> # Check whether --with-timeoutfactor was given.
> if test "${with_timeoutfactor+set}" = set; then :
> withval=$with_timeoutfactor; timeoutfactor=$withval
> diff --git a/configure.ac b/configure.ac
> index eb5bc6a131..68baeee4d7 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -169,6 +169,11 @@ AC_ARG_WITH([rtld-early-cflags],
> [rtld_early_cflags=])
> AC_SUBST(rtld_early_cflags)
>
> +AC_ARG_WITH([extra-version-id],
> + AS_HELP_STRING([--extra-version-id=STRING],
> + [specify an extra version string to use in internal ABI checks]),
> + [extra_version_id="$withval"])
> +
OK.
> AC_ARG_WITH([timeoutfactor],
> AS_HELP_STRING([--with-timeoutfactor=NUM],
> [specify an integer to scale the timeout]),
> diff --git a/elf/Makefile b/elf/Makefile
> index 3928a08787..bc68150a37 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -52,7 +52,6 @@ routines = \
> # The core dynamic linking functions are in libc for the static and
> # profiled libraries.
> dl-routines = \
> - dl-call-libc-early-init \
OK. Removed.
> dl-close \
> dl-debug \
> dl-debug-symbols \
> @@ -65,6 +64,7 @@ dl-routines = \
> dl-load \
> dl-lookup \
> dl-lookup-direct \
> + dl-lookup_libc_early_init \
OK. Added.
> dl-minimal-malloc \
> dl-misc \
> dl-object \
> diff --git a/elf/Versions b/elf/Versions
> index a9ff278de7..6260c0fe03 100644
> --- a/elf/Versions
> +++ b/elf/Versions
> @@ -29,8 +29,8 @@ libc {
> __placeholder_only_for_empty_version_map;
> }
> GLIBC_PRIVATE {
> - # functions used in other libraries
> - __libc_early_init;
> + # A pattern is needed here because the suffix is dynamically generated.
> + __libc_early_init_*;
OK. Confirmed with hash.
readelf -a -W ./libc.so.6 | grep __libc_early
2960: 0000000000148ed0 185 FUNC GLOBAL DEFAULT 10 __libc_early_init_jBsH275t@@GLIBC_PRIVATE
8976: 0000000000148ed0 185 FUNC GLOBAL DEFAULT 10 __libc_early_init_jBsH275t
>
> # Internal error handling support. Interposes the functions in ld.so.
> _dl_signal_exception; _dl_catch_exception;
> diff --git a/elf/dl-load.c b/elf/dl-load.c
> index 1ad0868dad..00e08b5500 100644
> --- a/elf/dl-load.c
> +++ b/elf/dl-load.c
> @@ -31,7 +31,6 @@
> #include <sys/param.h>
> #include <sys/stat.h>
> #include <sys/types.h>
> -#include <gnu/lib-names.h>
OK. Not required.
>
> /* Type for the buffer we put the ELF header and hopefully the program
> header. This buffer does not really have to be too large. In most
> @@ -1466,14 +1465,6 @@ cannot enable executable stack as shared object requires");
> add_name_to_object (l, ((const char *) D_PTR (l, l_info[DT_STRTAB])
> + l->l_info[DT_SONAME]->d_un.d_val));
>
OK. We are in _dl_map_object_from_fd ...
> - /* If we have newly loaded libc.so, update the namespace
> - description. */
> - if (GL(dl_ns)[nsid].libc_map == NULL
> - && l->l_info[DT_SONAME] != NULL
> - && strcmp (((const char *) D_PTR (l, l_info[DT_STRTAB])
> - + l->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0)
> - GL(dl_ns)[nsid].libc_map = l;
> -
OK. Remove the identification of libc from _dl_map_object_from_fd because we are going to put
it somewhere else.
> /* _dl_close can only eventually undo the module ID assignment (via
> remove_slotinfo) if this function returns a pointer to a link
> map. Therefore, delay this step until all possibilities for
> diff --git a/elf/dl-call-libc-early-init.c b/elf/dl-lookup_libc_early_init.c
> similarity index 66%
> rename from elf/dl-call-libc-early-init.c
> rename to elf/dl-lookup_libc_early_init.c
> index ee9860e3ab..64bc287a05 100644
> --- a/elf/dl-call-libc-early-init.c
> +++ b/elf/dl-lookup_libc_early_init.c
> @@ -1,4 +1,4 @@
> -/* Invoke the early initialization function in libc.so.
> +/* Find the address of the __libc_early_init function.
OK.
> Copyright (C) 2020-2022 Free Software Foundation, Inc.
> This file is part of the GNU C Library.
>
> @@ -16,26 +16,21 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#include <assert.h>
> #include <ldsodefs.h>
> #include <libc-early-init.h>
> #include <link.h>
> #include <stddef.h>
>
> -void
> -_dl_call_libc_early_init (struct link_map *libc_map, _Bool initial)
> +__typeof (__libc_early_init) *
> +_dl_lookup_libc_early_init (struct link_map *libc_map)
OK. Return function pointer.
> {
> - /* There is nothing to do if we did not actually load libc.so. */
> - if (libc_map == NULL)
> - return;
> -
> const ElfW(Sym) *sym
> - = _dl_lookup_direct (libc_map, "__libc_early_init",
> - 0x069682ac, /* dl_new_hash output. */
> + = _dl_lookup_direct (libc_map, LIBC_EARLY_INIT_NAME_STRING,
> + LIBC_EARLY_INIT_GNU_HASH,
OK. Lookup new mangled function.
> "GLIBC_PRIVATE",
> 0x0963cf85); /* _dl_elf_hash output. */
> - assert (sym != NULL);
> - __typeof (__libc_early_init) *early_init
> - = DL_SYMBOL_ADDRESS (libc_map, sym);
> - early_init (initial);
> + if (sym == NULL)
> + _dl_signal_error (0, libc_map->l_name, NULL, "\
> +ld.so/libc.so mismatch detected (upgrade in progress?)");
> + return DL_SYMBOL_ADDRESS (libc_map, sym);
OK. If we can't find the symbol then error out.
> }
> diff --git a/elf/dl-open.c b/elf/dl-open.c
> index a23e65926b..dcc24130fe 100644
> --- a/elf/dl-open.c
> +++ b/elf/dl-open.c
> @@ -760,8 +760,8 @@ dl_open_worker_begin (void *a)
> if (!args->libc_already_loaded)
> {
> /* dlopen cannot be used to load an initial libc by design. */
> - struct link_map *libc_map = GL(dl_ns)[args->nsid].libc_map;
> - _dl_call_libc_early_init (libc_map, false);
> + if (GL(dl_ns)[args->nsid].libc_map != NULL)
> + GL(dl_ns)[args->nsid].libc_map_early_init (false);
OK. Call the function pointer we loaded earlier.
> }
>
> args->worker_continue = true;
> diff --git a/elf/dl-version.c b/elf/dl-version.c
> index cda0889209..39514371ff 100644
> --- a/elf/dl-version.c
> +++ b/elf/dl-version.c
> @@ -23,6 +23,8 @@
> #include <string.h>
> #include <ldsodefs.h>
> #include <_itoa.h>
> +#include <gnu/lib-names.h>
> +#include <libc-early-init.h>
OK.
>
> #include <assert.h>
>
> @@ -359,6 +361,22 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
> }
> }
>
OK. This is *VERY* early in:
dl_main
version_check_doit
_dl_check_all_versions
_dl_check_map_version
This is quite early and a completely different approach, but it still works,
and we use the symbol we lookup later to avoid duplicate work.
> + /* Detect a libc.so loaded into this namespace. The
> + __libc_early_init lookup below means that we have to do this
> + after parsing the version data. */
> + if (GL(dl_ns)[map->l_ns].libc_map == NULL
> + && map->l_info[DT_SONAME] != NULL
> + && strcmp (((const char *) D_PTR (map, l_info[DT_STRTAB])
> + + map->l_info[DT_SONAME]->d_un.d_val), LIBC_SO) == 0)
> + {
> + /* Look up this symbol error to trigger a mismatch error before
s/error//g
> + relocation (which may call IFUNC resolvers, and those can
> + have an internal ABI dependency). */
> + GL(dl_ns)[map->l_ns].libc_map_early_init
> + = _dl_lookup_libc_early_init (map);
> + GL(dl_ns)[map->l_ns].libc_map = map;
OK. Early lookup just after we scan version names.
> + }
> +
> /* When there is a DT_VERNEED entry with libc.so on DT_NEEDED, issue
> an error if there is a DT_RELR entry without GLIBC_ABI_DT_RELR
> dependency. */
> diff --git a/elf/libc-early-init.h b/elf/libc-early-init.h
> index a8edfadfb0..ac8c204bc7 100644
> --- a/elf/libc-early-init.h
> +++ b/elf/libc-early-init.h
> @@ -19,13 +19,10 @@
> #ifndef _LIBC_EARLY_INIT_H
> #define _LIBC_EARLY_INIT_H
>
> +#include <libc_early_init_name.h>
> +
> struct link_map;
>
> -/* If LIBC_MAP is not NULL, look up the __libc_early_init symbol in it
> - and call this function, with INITIAL as the argument. */
> -void _dl_call_libc_early_init (struct link_map *libc_map, _Bool initial)
> - attribute_hidden;
OK.
> -
> /* In the shared case, this function is defined in libc.so and invoked
> from ld.so (or on the fist static dlopen) after complete relocation
> of a new loaded libc.so, but before user-defined ELF constructors
> @@ -33,6 +30,18 @@ void _dl_call_libc_early_init (struct link_map *libc_map, _Bool initial)
> startup code. If INITIAL is true, the libc being initialized is
> the libc for the main program. INITIAL is false for libcs loaded
> for audit modules, dlmopen, and static dlopen. */
> -void __libc_early_init (_Bool initial);
> +void __libc_early_init (_Bool initial)
> +#ifdef SHARED
> +/* Redirect to the actual implementation name. */
> + __asm__ (LIBC_EARLY_INIT_NAME_STRING)
OK.
> +#endif
> + ;
> +
> +/* Attempts to find the appropriately named __libc_early_init function
> + in LIBC_MAP. On lookup failure, an exception is signaled,
> + indicating an ld.so/libc.so mismatch. */
> +__typeof (__libc_early_init) *_dl_lookup_libc_early_init (struct link_map *
> + libc_map)
OK.
> + attribute_hidden;
>
> #endif /* _LIBC_EARLY_INIT_H */
> diff --git a/elf/rtld.c b/elf/rtld.c
> index cbbaf4a331..910075c37f 100644
> --- a/elf/rtld.c
> +++ b/elf/rtld.c
> @@ -1707,15 +1707,6 @@ dl_main (const ElfW(Phdr) *phdr,
> /* Extract the contents of the dynamic section for easy access. */
> elf_get_dynamic_info (main_map, false, false);
>
> - /* If the main map is libc.so, update the base namespace to
> - refer to this map. If libc.so is loaded later, this happens
> - in _dl_map_object_from_fd. */
> - if (main_map->l_info[DT_SONAME] != NULL
> - && (strcmp (((const char *) D_PTR (main_map, l_info[DT_STRTAB])
> - + main_map->l_info[DT_SONAME]->d_un.d_val), LIBC_SO)
> - == 0))
> - GL(dl_ns)[LM_ID_BASE].libc_map = main_map;
> -
OK. Refactor.
> /* Set up our cache of pointers into the hash table. */
> _dl_setup_hash (main_map);
> }
> @@ -2386,7 +2377,8 @@ dl_main (const ElfW(Phdr) *phdr,
> /* Relocation is complete. Perform early libc initialization. This
> is the initial libc, even if audit modules have been loaded with
> other libcs. */
> - _dl_call_libc_early_init (GL(dl_ns)[LM_ID_BASE].libc_map, true);
> + if (GL(dl_ns)[LM_ID_BASE].libc_map != NULL)
> + GL(dl_ns)[LM_ID_BASE].libc_map_early_init (true);
OK. Call function pointer.
>
> /* Do any necessary cleanups for the startup OS interface code.
> We do these now so that no calls are made after rtld re-relocation
> diff --git a/manual/install.texi b/manual/install.texi
> index c775005581..6d43599a47 100644
> --- a/manual/install.texi
> +++ b/manual/install.texi
> @@ -144,6 +144,15 @@ dynamic linker diagnostics to run on CPUs which are not compatible with
> the rest of @theglibc{}, for example, due to compiler flags which target
> a later instruction set architecture (ISA).
>
> +@item --with-extra-version-id=@var{string}
> +Use @var{string} as part of the fingerprint that is used by the dynamic
> +linker to detect an incompatible version of @file{libc.so}. For
> +example, @var{string} could be the full package version and release
> +string used by a distribution build of @theglibc{}. This way,
> +concurrent process creation during a package update will fail with an
> +error message, @emph{ld.so/libc.so mismatch detected (upgrade in
> +progress?)}, rather than crashing mysteriously.
OK.
> +
> @item --with-timeoutfactor=@var{NUM}
> Specify an integer @var{NUM} to scale the timeout of test programs.
> This factor can be changed at run time using @env{TIMEOUTFACTOR}
> diff --git a/scripts/libc_early_init_name.py b/scripts/libc_early_init_name.py
> new file mode 100644
> index 0000000000..465cbe9dae
> --- /dev/null
> +++ b/scripts/libc_early_init_name.py
> @@ -0,0 +1,85 @@
> +#!/usr/bin/python3
> +# Compute the hash-based name of the __libc_early_init function.
> +# Copyright (C) 2022 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
> +# <https://www.gnu.org/licenses/>.
> +
> +"""Compute the name of the __libc_early_init function, which is used
> +as a protocol version marker between ld.so and libc.so.
> +
> +The name contains a hash suffix, and the hash changes if certain key
> +files in the source tree change. Distributions can also configure
> +with --with-extra-version-id, to make the computed hash dependent on
> +the package version.
> +
> +"""
> +
> +import argparse
> +import hashlib
> +import os
> +import string
> +import sys
> +
> +# Make available glibc Python modules.
> +sys.path.append(os.path.dirname(os.path.realpath(__file__)))
> +
> +import glibcelf
> +
> +# Parse the command line.
> +parser = argparse.ArgumentParser(description=__doc__)
> +parser.add_argument('--output', metavar='PATH',
> + help='path to header file this tool generates')
> +parser.add_argument('--extra-version-id', metavar='ID',
> + help='extra string to influence hash computation')
> +parser.add_argument('inputs', metavar='PATH', nargs='*',
> + help='files whose contents influences the generated hash')
> +opts = parser.parse_args()
> +
> +# Obtain the blobs that affect the generated hash.
> +blobs = [(opts.extra_version_id or '').encode('UTF-8')]
> +for path in opts.inputs:
> + with open(path, 'rb') as inp:
> + blobs.append(inp.read())
> +
> +# Hash the file boundaries.
> +md = hashlib.sha256()
> +md.update(repr([len(blob) for blob in blobs]).encode('UTF-8'))
> +
> +# And then hash the file contents. Do not hash the paths, to avoid
> +# impacting reproducibility.
> +for blob in blobs:
> + md.update(blob)
> +
> +# These are the bits used to compute the suffix.
> +derived_bits = int.from_bytes(md.digest(), byteorder='big', signed=False)
> +
> +# These digits are used in the suffix (should result in base-62 encoding).
> +# They must be valid in C identifiers.
> +digits = string.digits + string.ascii_letters
> +
> +# Generate eight digits as a suffix. They should provide enough
> +# uniqueness (47.6 bits).
> +name = '__libc_early_init_'
> +for n in range(8):
> + name += digits[derived_bits % len(digits)]
> + derived_bits //= len(digits)
> +
> +# Write the output file.
> +with open(opts.output, 'w') if opts.output else sys.stdout as out:
> + out.write('#define LIBC_EARLY_INIT_NAME {}\n'.format(name))
> + out.write('#define LIBC_EARLY_INIT_NAME_STRING "{}"\n'.format(name))
> + out.write('#define LIBC_EARLY_INIT_GNU_HASH {}\n'.format(
> + glibcelf.gnu_hash(name)))
OK. Compute hash.
> diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
> index 050a3032de..275dbc95ce 100644
> --- a/sysdeps/generic/ldsodefs.h
> +++ b/sysdeps/generic/ldsodefs.h
> @@ -333,6 +333,10 @@ struct rtld_global
> its link map. */
> struct link_map *libc_map;
>
> + /* __libc_early_init function in libc_map. Initialized at the
> + same time as libc_map. */
> + void (*libc_map_early_init) (_Bool);
OK. Function pointer.
> +
> /* Search table for unique objects. */
> struct unique_sym_table
> {
>
> base-commit: bd13cb19f5e15e9e9a92a536e755fd93a97a67f6
>
--
Cheers,
Carlos.
More information about the Libc-alpha
mailing list