1
Fork 0
mirror of git://git.sv.gnu.org/emacs.git synced 2025-12-25 23:10:47 -08:00
emacs/m4/readlink.m4
Paul Eggert ae0d725005 [ChangeLog]
Work around some portability problems with symlinks.
* Makefile.in (GNULIB_MODULES): Add lstat, readlink, symlink.
* configure.in (lstat, HAVE_LSTAT): Remove special hack.
* lib/lstat.c, lib/readlink.c, lib/stat.c, lib/symlink.c:
* m4/dos.m4, m4/lstat.m4, m4/readlink.m4, m4/stat.m4, m4/symlink.m4:
New files, automatically generated from gnulib.
* aclocal.m4, configure, lib/Makefile.in, lib/gnulib.mk:
* lib/stdlib.in.h, m4/gl-comp.m4, m4/stdlib_h.m4: Regenerate.

2011-02-22  Paul Eggert  <eggert@cs.ucla.edu>
[src/ChangeLog]
Work around some portability problems with symlinks.
* fileio.c (Frename_file, Fmake_symbolic_link, Ffile_symlink_p):
Simplify the code by assuming that the readlink and symlink calls
exist, even if they always fail on this host.
(Ffile_readable_p): Likewise, for fifos.
* config.in: Regenerate.
2011-02-22 11:30:07 -08:00

62 lines
2.2 KiB
Text

# readlink.m4 serial 9
dnl Copyright (C) 2003, 2007, 2009-2011 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_FUNC_READLINK],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_CHECK_FUNCS_ONCE([readlink])
if test $ac_cv_func_readlink = no; then
HAVE_READLINK=0
AC_LIBOBJ([readlink])
gl_PREREQ_READLINK
else
AC_CACHE_CHECK([whether readlink signature is correct],
[gl_cv_decl_readlink_works],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
/* Cause compilation failure if original declaration has wrong type. */
ssize_t readlink (const char *, char *, size_t);]])],
[gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
dnl Solaris 9 ignores trailing slash.
dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
[gl_cv_func_readlink_works],
[# We have readlink, so assume ln -s works.
ln -s conftest.no-such conftest.link
ln -s conftest.link conftest.lnk2
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
]], [[char buf[20];
return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
[gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
[gl_cv_func_readlink_works="guessing no"])
rm -f conftest.link conftest.lnk2])
if test "$gl_cv_func_readlink_works" != yes; then
AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
fails to recognize a trailing slash.])
REPLACE_READLINK=1
AC_LIBOBJ([readlink])
elif test "$gl_cv_decl_readlink_works" != yes; then
REPLACE_READLINK=1
AC_LIBOBJ([readlink])
fi
fi
])
# Like gl_FUNC_READLINK, except prepare for separate compilation (no AC_LIBOBJ).
AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
[
AC_CHECK_FUNCS_ONCE([readlink])
gl_PREREQ_READLINK
])
# Prerequisites of lib/readlink.c.
AC_DEFUN([gl_PREREQ_READLINK],
[
:
])