RFC: Add --enable-prepend-sysdeps=

["H.J. Lu" <hongjiu dot lu at intel dot com>]

Hi,

Here is another approach to fix BZ #14200.  This patch adds
--enable-prepend-sysdeps=.  When you configure glibc with

-enable-prepend-sysdeps=unix/sysv/linux/x86/mx32

you will get -mx32 for ILP32_OFFBIG.  Any comments?

Thanks.


H.J.
---
2012-07-19  H.J. Lu  <hongjiu.lu@intel.com>

	[BZ #14200]
	* configure.in: Add --enable-prepend-sysdeps=.
	* configure: Regenerated.
	* sysdeps/unix/sysv/linux/x86/bits/environments.h
	(_POSIX_V7_ILP32_OFF32): Defined as 1 only if __x86_64__ isn't
	defined.
	(_POSIX_V6_ILP32_OFF32): Likewise.
	(_XBS5_ILP32_OFF32): Likewise.
	* sysdeps/unix/sysv/linux/x86/mx32/bits/environments.h: New file.

diff --git a/configure.in b/configure.in
index 6b6dde5..13880e4 100644
--- a/configure.in
+++ b/configure.in
@@ -153,6 +153,18 @@ AC_ARG_ENABLE([add-ons],
 			      search for add-ons if no parameter given]),
 			     , [enable_add_ons=yes])
 
+dnl Generic infrastructure to prepend sysdeps list.
+AC_ARG_ENABLE([prepend-sysdeps],
+	      AC_HELP_STRING([--enable-prepend-sysdeps=@DIRS...@],
+			     [Prepend DIR1,DIR2,... to sysdep search list]),
+			     , [enable_prepend_sysdeps=yes])
+
+case "$enable_prepend_sysdeps" in
+''|no) prepend_sysdeps= ;;
+yes|'*') AC_MSG_ERROR([invalid --enable-prepend-sysdeps option]);;
+*) prepend_sysdeps=`echo "$enable_prepend_sysdeps" | sed 's/,/ /g'`;;
+esac
+
 AC_ARG_ENABLE([hidden-plt],
 	      AC_HELP_STRING([--disable-hidden-plt],
 			     [do not hide internal function calls to avoid PLT]),
@@ -832,6 +844,43 @@ done
 # Add the default directories.
 default_sysnames="sysdeps/generic"
 sysnames="$names $default_sysnames"
+
+# Prepend directories.
+if test -n "$prepend_sysdeps"; then
+  set $prepend_sysdeps
+  names=
+  while test $# -gt 0; do
+    name=$1
+    shift
+
+    case " $names " in *" sysdeps/$name "*)
+      # Already in the list.
+      continue
+    esac
+
+    found=no
+    if test -d $srcdir/sysdeps/$name; then
+      names="$names sysdeps/$name"
+      found=yes
+    fi
+    for d in $add_ons_pfx ''; do
+      try="${d}sysdeps/$name"
+      case $d in
+      /*) try_srcdir= ;;
+      *) try_srcdir=$srcdir/ ;;
+      esac
+      if test -d $try_srcdir$try; then
+	names="$names $try"
+	found=yes
+      fi
+    done
+    if test $found = no; then
+      AC_MSG_ERROR(--enable-prepend-sysdeps specifies nonexistent $name)
+    fi
+  done
+  sysnames="$names $sysnames"
+fi
+
 AC_SUBST(sysnames)
 # The other names were emitted during the scan.
 AC_MSG_RESULT($default_sysnames)
diff --git a/sysdeps/unix/sysv/linux/x86/bits/environments.h b/sysdeps/unix/sysv/linux/x86/bits/environments.h
index 793a04f..cdaa1e5 100644
--- a/sysdeps/unix/sysv/linux/x86/bits/environments.h
+++ b/sysdeps/unix/sysv/linux/x86/bits/environments.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 1999, 2001, 2004, 2009 Free Software Foundation, Inc.
+/* Copyright (C) 1999-2012 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
@@ -64,15 +64,19 @@
 
 #else /* __WORDSIZE == 32 */
 
-/* By default we have 32-bit wide `int', `long int', pointers and `off_t'
-   and all platforms support LFS.  */
-# define _POSIX_V7_ILP32_OFF32	1
+/* We have 32-bit wide `int', `long int' and pointers and all platforms
+   support LFS.  -mx32 has 64-bit wide `off_t'.  */
 # define _POSIX_V7_ILP32_OFFBIG	1
-# define _POSIX_V6_ILP32_OFF32	1
-# define _POSIX_V6_ILP32_OFFBIG	1
-# define _XBS5_ILP32_OFF32	1
+# define _POSIX_V6_ILP32_OFFBIG 1
 # define _XBS5_ILP32_OFFBIG	1
 
+# ifndef __x86_64__
+/* -m32 has 32-bit wide `off_t'.  */
+#  define _POSIX_V7_ILP32_OFF32	1
+#  define _POSIX_V6_ILP32_OFF32	1
+#  define _XBS5_ILP32_OFF32	1
+# endif
+
 /* We optionally provide an environment with the above size but an 64-bit
    side `off_t'.  Therefore we don't define _POSIX_V7_ILP32_OFFBIG.  */
 
diff --git a/sysdeps/unix/sysv/linux/x86/mx32/bits/environments.h b/sysdeps/unix/sysv/linux/x86/mx32/bits/environments.h
new file mode 100644
index 0000000..ac9ed07
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/mx32/bits/environments.h
@@ -0,0 +1,100 @@
+/* Copyright (C) 2012 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 _UNISTD_H
+# error "Never include this file directly.  Use <unistd.h> instead"
+#endif
+
+#include <bits/wordsize.h>
+
+/* This header should define the following symbols under the described
+   situations.  A value `1' means that the model is always supported,
+   `-1' means it is never supported.  Undefined means it cannot be
+   statically decided.
+
+   _POSIX_V7_ILP32_OFF32   32bit int, long, pointers, and off_t type
+   _POSIX_V7_ILP32_OFFBIG  32bit int, long, and pointers and larger off_t type
+
+   _POSIX_V7_LP64_OFF32	   64bit long and pointers and 32bit off_t type
+   _POSIX_V7_LPBIG_OFFBIG  64bit long and pointers and large off_t type
+
+   The macros _POSIX_V6_ILP32_OFF32, _POSIX_V6_ILP32_OFFBIG,
+   _POSIX_V6_LP64_OFF32, _POSIX_V6_LPBIG_OFFBIG, _XBS5_ILP32_OFF32,
+   _XBS5_ILP32_OFFBIG, _XBS5_LP64_OFF32, and _XBS5_LPBIG_OFFBIG were
+   used in previous versions of the Unix standard and are available
+   only for compatibility.
+*/
+
+#if __WORDSIZE == 64
+
+/* Environments with 32-bit wide pointers are optionally provided.
+   Therefore following macros aren't defined:
+   # undef _POSIX_V7_ILP32_OFF32
+   # undef _POSIX_V7_ILP32_OFFBIG
+   # undef _POSIX_V6_ILP32_OFF32
+   # undef _POSIX_V6_ILP32_OFFBIG
+   # undef _XBS5_ILP32_OFF32
+   # undef _XBS5_ILP32_OFFBIG
+   and users need to check at runtime.  */
+
+/* We also have no use (for now) for an environment with bigger pointers
+   and offsets.  */
+# define _POSIX_V7_LPBIG_OFFBIG	-1
+# define _POSIX_V6_LPBIG_OFFBIG	-1
+# define _XBS5_LPBIG_OFFBIG	-1
+
+/* By default we have 64-bit wide `long int', pointers and `off_t'.  */
+# define _POSIX_V7_LP64_OFF64	1
+# define _POSIX_V6_LP64_OFF64	1
+# define _XBS5_LP64_OFF64	1
+
+#else /* __WORDSIZE == 32 */
+
+/* We have 32-bit wide `int', `long int' and pointers and all platforms
+   support LFS.  -mx32 has 64-bit wide `off_t'.  */
+# define _POSIX_V7_ILP32_OFFBIG	1
+# define _POSIX_V6_ILP32_OFFBIG 1
+# define _XBS5_ILP32_OFFBIG	1
+
+# ifndef __x86_64__
+/* -m32 has 32-bit wide `off_t'.  */
+#  define _POSIX_V7_ILP32_OFF32	1
+#  define _POSIX_V6_ILP32_OFF32	1
+#  define _XBS5_ILP32_OFF32	1
+# endif
+
+/* We optionally provide an environment with the above size but an 64-bit
+   side `off_t'.  Therefore we don't define _POSIX_V7_ILP32_OFFBIG.  */
+
+/* Environments with 64-bit wide pointers can be provided,
+   so these macros aren't defined:
+   # undef _POSIX_V7_LP64_OFF64
+   # undef _POSIX_V7_LPBIG_OFFBIG
+   # undef _POSIX_V6_LP64_OFF64
+   # undef _POSIX_V6_LPBIG_OFFBIG
+   # undef _XBS5_LP64_OFF64
+   # undef _XBS5_LPBIG_OFFBIG
+   and sysconf tests for it at runtime.  */
+
+#endif /* __WORDSIZE == 32 */
+
+#define __ILP32_OFF32_CFLAGS	"-m32"
+#define __ILP32_OFF32_LDFLAGS	"-m32"
+#define __ILP32_OFFBIG_CFLAGS	"-mx32"
+#define __ILP32_OFFBIG_LDFLAGS	"-mx32"
+#define __LP64_OFF64_CFLAGS	"-m64"
+#define __LP64_OFF64_LDFLAGS	"-m64"
-- 
1.7.10.4