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# fchmodat.m4
# serial 8
dnl Copyright (C) 2004-2025 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.
# Written by Jim Meyering.
AC_DEFUN([gl_FUNC_FCHMODAT],
[
AC_REQUIRE([gl_SYS_STAT_H_DEFAULTS])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CHECK_FUNCS_ONCE([fchmodat lchmod])
if test $ac_cv_func_fchmodat != yes; then
HAVE_FCHMODAT=0
else
AC_CACHE_CHECK(
[whether fchmodat works],
[gl_cv_func_fchmodat_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[
AC_INCLUDES_DEFAULT[
#include <fcntl.h>
#ifndef S_IRUSR
#define S_IRUSR 0400
#endif
#ifndef S_IWUSR
#define S_IWUSR 0200
#endif
#ifndef S_IRWXU
#define S_IRWXU 0700
#endif
#ifndef S_IRWXG
#define S_IRWXG 0070
#endif
#ifndef S_IRWXO
#define S_IRWXO 0007
#endif
]GL_MDA_DEFINES],
[[
int permissive = S_IRWXU | S_IRWXG | S_IRWXO;
int desired = S_IRUSR | S_IWUSR;
int result = 0;
#define file "conftest.fchmodat"
struct stat st;
if (creat (file, permissive) < 0)
return 1;
/* Test whether fchmodat rejects a trailing slash on a non-directory.
This test fails on AIX 7.2. */
if (fchmodat (AT_FDCWD, file "/", desired, 0) == 0)
result |= 2;
/* Test whether fchmodat+AT_SYMLINK_NOFOLLOW works on non-symlinks.
This test fails on GNU/Linux with glibc 2.31 (but not on
GNU/kFreeBSD nor GNU/Hurd) and Cygwin 2.9. */
if (fchmodat (AT_FDCWD, file, desired, AT_SYMLINK_NOFOLLOW) != 0)
result |= 4;
if (stat (file, &st) != 0)
return 1;
if ((st.st_mode & permissive) != desired)
result |= 4;
return result;
]])],
[gl_cv_func_fchmodat_works=yes],
[case $? in
2) gl_cv_func_fchmodat_works='nearly' ;;
*) gl_cv_func_fchmodat_works=no ;;
esac
],
[case "$host_os" in
# Guess no on Linux with glibc and Cygwin.
linux-gnu* | cygwin*) gl_cv_func_fchmodat_works="guessing no" ;;
# Guess 'nearly' on AIX.
aix*) gl_cv_func_fchmodat_works="guessing nearly" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_fchmodat_works="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.fchmodat])
case "$gl_cv_func_fchmodat_works" in
*yes) ;;
*nearly)
AC_DEFINE([HAVE_NEARLY_WORKING_FCHMODAT], [1],
[Define to 1 if fchmodat works, except for the trailing slash handling.])
REPLACE_FCHMODAT=1
;;
*)
AC_DEFINE([NEED_FCHMODAT_NONSYMLINK_FIX], [1],
[Define to 1 if fchmodat+AT_SYMLINK_NOFOLLOW does not work right on non-symlinks.])
REPLACE_FCHMODAT=1
;;
esac
fi
])
# Prerequisites of lib/fchmodat.c.
AC_DEFUN([gl_PREREQ_FCHMODAT],
[
gl_CHECK_FUNCS_ANDROID([readlinkat], [[#include <unistd.h>]])
:
])
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