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emacs/m4/utimensat.m4
2021-01-22 12:02:55 -08:00

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# serial 9
# See if we need to provide utimensat replacement.
dnl Copyright (C) 2009-2021 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 Eric Blake.
AC_DEFUN([gl_FUNC_UTIMENSAT],
[
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([utimensat])
if test $ac_cv_func_utimensat = no; then
HAVE_UTIMENSAT=0
else
AC_CACHE_CHECK([whether utimensat works],
[gl_cv_func_utimensat_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM([[
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
]GL_MDA_DEFINES],
[[int result = 0;
const char *f = "conftest.file";
if (close (creat (f, 0600)))
return 1;
/* Test whether a trailing slash is handled correctly.
This fails on AIX 7.2. */
{
struct timespec ts[2];
ts[0].tv_sec = 345183300; ts[0].tv_nsec = 0;
ts[1] = ts[0];
if (utimensat (AT_FDCWD, "conftest.file/", ts, 0) == 0)
result |= 2;
}
/* Test whether the AT_SYMLINK_NOFOLLOW flag is supported. */
{
if (utimensat (AT_FDCWD, f, NULL, AT_SYMLINK_NOFOLLOW))
result |= 4;
}
/* Test whether UTIME_NOW and UTIME_OMIT work. */
{
struct timespec ts[2];
ts[0].tv_sec = 1;
ts[0].tv_nsec = UTIME_OMIT;
ts[1].tv_sec = 1;
ts[1].tv_nsec = UTIME_NOW;
if (utimensat (AT_FDCWD, f, ts, 0))
result |= 8;
}
sleep (1);
{
struct stat st;
struct timespec ts[2];
ts[0].tv_sec = 1;
ts[0].tv_nsec = UTIME_NOW;
ts[1].tv_sec = 1;
ts[1].tv_nsec = UTIME_OMIT;
if (utimensat (AT_FDCWD, f, ts, 0))
result |= 16;
if (stat (f, &st))
result |= 32;
else if (st.st_ctime < st.st_atime)
result |= 64;
}
return result;
]])],
[gl_cv_func_utimensat_works=yes],
[case $? in
2) gl_cv_func_utimensat_works='nearly' ;;
*) gl_cv_func_utimensat_works=no ;;
esac
],
[case "$host_os" in
# Guess yes on Linux or glibc systems.
linux-* | linux | *-gnu* | gnu*)
gl_cv_func_utimensat_works="guessing yes" ;;
# Guess 'nearly' on AIX.
aix*)
gl_cv_func_utimensat_works="guessing nearly" ;;
# If we don't know, obey --enable-cross-guesses.
*)
gl_cv_func_utimensat_works="$gl_cross_guess_normal" ;;
esac
])
])
case "$gl_cv_func_utimensat_works" in
*yes)
;;
*nearly)
AC_DEFINE([HAVE_NEARLY_WORKING_UTIMENSAT], [1],
[Define to 1 if utimensat works, except for the trailing slash handling.])
REPLACE_UTIMENSAT=1
;;
*)
REPLACE_UTIMENSAT=1
;;
esac
fi
])