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emacs/m4/fchmodat.m4
Paul Eggert ba05d005e5 Update copyright year to 2021
Run "TZ=UTC0 admin/update-copyright".
2021-01-01 01:13:56 -08:00

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# fchmodat.m4 serial 5
dnl Copyright (C) 2004-2021 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 $ac_cv_func_fchmodat != yes; then
HAVE_FCHMODAT=0
else
AC_CACHE_CHECK(
[whether fchmodat+AT_SYMLINK_NOFOLLOW works on non-symlinks],
[gl_cv_func_fchmodat_works],
[dnl This test fails on GNU/Linux with glibc 2.31 (but not on
dnl GNU/kFreeBSD nor GNU/Hurd) and Cygwin 2.9.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[
AC_INCLUDES_DEFAULT[
#include <fcntl.h>
#ifndef S_IRUSR
#define S_IRUSR 0400
#endif
#ifndef S_IWUSR
#define S_IWUSR 0200
#endif
#ifndef S_IRWXU
#define S_IRWXU 0700
#endif
#ifndef S_IRWXG
#define S_IRWXG 0070
#endif
#ifndef S_IRWXO
#define S_IRWXO 0007
#endif
]GL_MDA_DEFINES],
[[
int permissive = S_IRWXU | S_IRWXG | S_IRWXO;
int desired = S_IRUSR | S_IWUSR;
static char const f[] = "conftest.fchmodat";
struct stat st;
if (creat (f, permissive) < 0)
return 1;
if (fchmodat (AT_FDCWD, f, desired, AT_SYMLINK_NOFOLLOW) != 0)
return 1;
if (stat (f, &st) != 0)
return 1;
return ! ((st.st_mode & permissive) == desired);
]])],
[gl_cv_func_fchmodat_works=yes],
[gl_cv_func_fchmodat_works=no],
[case "$host_os" in
dnl Guess no on Linux with glibc and Cygwin, yes otherwise.
linux-gnu* | cygwin*) gl_cv_func_fchmodat_works="guessing no" ;;
*) gl_cv_func_fchmodat_works="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.fchmodat])
case $gl_cv_func_fchmodat_works in
*yes) ;;
*)
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],
[
AC_CHECK_FUNCS_ONCE([lchmod])
:
])