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# chown.m4
# serial 36
dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2025 Free Software
dnl 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.
dnl This file is offered as-is, without any warranty.
# Determine whether we need the chown wrapper.
# chown should accept arguments of -1 for uid and gid, and it should
# dereference symlinks. If it doesn't, arrange to use the replacement
# function.
# From Jim Meyering.
# This is taken from the following Autoconf patch:
# https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
AC_DEFUN([AC_FUNC_CHOWN],
[
AC_REQUIRE([AC_TYPE_UID_T])dnl
AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
AC_CHECK_HEADERS([unistd.h])
AC_CACHE_CHECK([for working chown],
[ac_cv_func_chown_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[AC_INCLUDES_DEFAULT
[#include <fcntl.h>
]GL_MDA_DEFINES],
[[
char *f = "conftest.chown";
struct stat before, after;
if (creat (f, 0600) < 0)
return 1;
if (stat (f, &before) < 0)
return 1;
if (chown (f, (uid_t) -1, (gid_t) -1) == -1)
return 1;
if (stat (f, &after) < 0)
return 1;
return ! (before.st_uid == after.st_uid && before.st_gid == after.st_gid);
]])
],
[ac_cv_func_chown_works=yes],
[ac_cv_func_chown_works=no],
[case "$host_os" in # ((
# Guess yes on Linux systems.
linux-* | linux) ac_cv_func_chown_works="guessing yes" ;;
# Guess yes on glibc systems.
*-gnu* | gnu*) ac_cv_func_chown_works="guessing yes" ;;
# Guess no on native Windows.
mingw* | windows*) ac_cv_func_chown_works="guessing no" ;;
# If we don't know, obey --enable-cross-guesses.
*) ac_cv_func_chown_works="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.chown
])
case "$ac_cv_func_chown_works" in
*yes)
AC_DEFINE([HAVE_CHOWN], [1],
[Define to 1 if your system has a working `chown' function.])
;;
esac
])# AC_FUNC_CHOWN
AC_DEFUN_ONCE([gl_FUNC_CHOWN],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([AC_TYPE_UID_T])
AC_REQUIRE([AC_FUNC_CHOWN])
AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CHECK_FUNCS_ONCE([chown fchown])
dnl mingw lacks chown altogether.
if test $ac_cv_func_chown = no; then
HAVE_CHOWN=0
else
dnl Some old systems treated chown like lchown.
case "$gl_cv_func_chown_follows_symlink" in
*yes) ;;
*) REPLACE_CHOWN=1 ;;
esac
dnl Some old systems tried to use uid/gid -1 literally.
case "$ac_cv_func_chown_works" in
*no)
AC_DEFINE([CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE], [1],
[Define if chown is not POSIX compliant regarding IDs of -1.])
REPLACE_CHOWN=1
;;
esac
dnl Solaris 9 ignores trailing slash.
dnl FreeBSD 7.2 mishandles trailing slash on symlinks.
dnl Likewise for AIX 7.1.
AC_CACHE_CHECK([whether chown honors trailing slash],
[gl_cv_func_chown_slash_works],
[touch conftest.file && rm -f conftest.link
AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
]GL_MDA_DEFINES],
[[if (symlink ("conftest.file", "conftest.link")) return 1;
if (chown ("conftest.link/", getuid (), getgid ()) == 0) return 2;
]])],
[gl_cv_func_chown_slash_works=yes],
[gl_cv_func_chown_slash_works=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_chown_slash_works="guessing yes" ;;
# Guess yes on musl systems.
*-musl*) gl_cv_func_chown_slash_works="guessing yes" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_chown_slash_works="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.link conftest.file])
case "$gl_cv_func_chown_slash_works" in
*yes) ;;
*)
AC_DEFINE([CHOWN_TRAILING_SLASH_BUG], [1],
[Define to 1 if chown mishandles trailing slash.])
REPLACE_CHOWN=1
;;
esac
dnl OpenBSD fails to update ctime if ownership does not change.
AC_CACHE_CHECK([whether chown always updates ctime],
[gl_cv_func_chown_ctime_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
]GL_MDA_DEFINES],
[[struct stat st1, st2;
if (close (creat ("conftest.file", 0600))) return 1;
if (stat ("conftest.file", &st1)) return 2;
sleep (1);
if (chown ("conftest.file", st1.st_uid, st1.st_gid)) return 3;
if (stat ("conftest.file", &st2)) return 4;
if (st2.st_ctime <= st1.st_ctime) return 5;
]])],
[gl_cv_func_chown_ctime_works=yes],
[gl_cv_func_chown_ctime_works=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_chown_ctime_works="guessing yes" ;;
# Guess yes on musl systems.
*-musl*) gl_cv_func_chown_ctime_works="guessing yes" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_chown_ctime_works="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.file])
case "$gl_cv_func_chown_ctime_works" in
*yes) ;;
*)
AC_DEFINE([CHOWN_CHANGE_TIME_BUG], [1], [Define to 1 if chown fails
to change ctime when at least one argument was not -1.])
REPLACE_CHOWN=1
;;
esac
fi
])
# Determine whether chown follows symlinks (it should).
AC_DEFUN_ONCE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
[
AC_CACHE_CHECK(
[whether chown dereferences symlinks],
[gl_cv_func_chown_follows_symlink],
[
AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
]GL_MDA_DEFINES[
int
main ()
{
int result = 0;
char const *dangling_symlink = "conftest.dangle";
unlink (dangling_symlink);
if (symlink ("conftest.no-such", dangling_symlink))
abort ();
/* Exit successfully on a conforming system,
i.e., where chown must fail with ENOENT. */
if (chown (dangling_symlink, getuid (), getgid ()) == 0)
result |= 1;
if (errno != ENOENT)
result |= 2;
return result;
}
]])],
[gl_cv_func_chown_follows_symlink=yes],
[gl_cv_func_chown_follows_symlink=no],
[gl_cv_func_chown_follows_symlink="guessing yes"]
)
]
)
case "$gl_cv_func_chown_follows_symlink" in
*yes) ;;
*)
AC_DEFINE([CHOWN_MODIFIES_SYMLINK], [1],
[Define if chown modifies symlinks.])
;;
esac
])
|
