3 dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2024 Free Software Foundation, Inc.
4 dnl This file is free software; the Free Software Foundation
5 dnl gives unlimited permission to copy and/or distribute it,
6 dnl with or without modifications, as long as this notice is preserved.
8 # Determine whether we need the chown wrapper.
10 # chown should accept arguments of -1 for uid and gid, and it should
11 # dereference symlinks. If it doesn't, arrange to use the replacement
16 # This is taken from the following Autoconf patch:
17 # https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
18 AC_DEFUN([AC_FUNC_CHOWN],
20 AC_REQUIRE([AC_TYPE_UID_T])dnl
21 AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
22 AC_CHECK_HEADERS([unistd.h])
23 AC_CACHE_CHECK([for working chown],
24 [ac_cv_func_chown_works],
31 char *f = "conftest.chown";
32 struct stat before, after;
34 if (creat (f, 0600) < 0)
36 if (stat (f, &before) < 0)
38 if (chown (f, (uid_t) -1, (gid_t) -1) == -1)
40 if (stat (f, &after) < 0)
42 return ! (before.st_uid == after.st_uid && before.st_gid == after.st_gid);
45 [ac_cv_func_chown_works=yes],
46 [ac_cv_func_chown_works=no],
47 [case "$host_os" in # ((
48 # Guess yes on Linux systems.
49 linux-* | linux) ac_cv_func_chown_works="guessing yes" ;;
50 # Guess yes on glibc systems.
51 *-gnu* | gnu*) ac_cv_func_chown_works="guessing yes" ;;
52 # Guess no on native Windows.
53 mingw* | windows*) ac_cv_func_chown_works="guessing no" ;;
54 # If we don't know, obey --enable-cross-guesses.
55 *) ac_cv_func_chown_works="$gl_cross_guess_normal" ;;
60 case "$ac_cv_func_chown_works" in
62 AC_DEFINE([HAVE_CHOWN], [1],
63 [Define to 1 if your system has a working `chown' function.])
68 AC_DEFUN_ONCE([gl_FUNC_CHOWN],
70 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
71 AC_REQUIRE([AC_TYPE_UID_T])
72 AC_REQUIRE([AC_FUNC_CHOWN])
73 AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
74 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
75 AC_CHECK_FUNCS_ONCE([chown fchown])
77 dnl mingw lacks chown altogether.
78 if test $ac_cv_func_chown = no; then
81 dnl Some old systems treated chown like lchown.
82 case "$gl_cv_func_chown_follows_symlink" in
87 dnl Some old systems tried to use uid/gid -1 literally.
88 case "$ac_cv_func_chown_works" in
90 AC_DEFINE([CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE], [1],
91 [Define if chown is not POSIX compliant regarding IDs of -1.])
96 dnl Solaris 9 ignores trailing slash.
97 dnl FreeBSD 7.2 mishandles trailing slash on symlinks.
98 dnl Likewise for AIX 7.1.
99 AC_CACHE_CHECK([whether chown honors trailing slash],
100 [gl_cv_func_chown_slash_works],
101 [touch conftest.file && rm -f conftest.link
102 AC_RUN_IFELSE([AC_LANG_PROGRAM([[
107 [[if (symlink ("conftest.file", "conftest.link")) return 1;
108 if (chown ("conftest.link/", getuid (), getgid ()) == 0) return 2;
110 [gl_cv_func_chown_slash_works=yes],
111 [gl_cv_func_chown_slash_works=no],
113 # Guess yes on glibc systems.
114 *-gnu*) gl_cv_func_chown_slash_works="guessing yes" ;;
115 # Guess yes on musl systems.
116 *-musl*) gl_cv_func_chown_slash_works="guessing yes" ;;
117 # If we don't know, obey --enable-cross-guesses.
118 *) gl_cv_func_chown_slash_works="$gl_cross_guess_normal" ;;
121 rm -f conftest.link conftest.file])
122 case "$gl_cv_func_chown_slash_works" in
125 AC_DEFINE([CHOWN_TRAILING_SLASH_BUG], [1],
126 [Define to 1 if chown mishandles trailing slash.])
131 dnl OpenBSD fails to update ctime if ownership does not change.
132 AC_CACHE_CHECK([whether chown always updates ctime],
133 [gl_cv_func_chown_ctime_works],
134 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
139 #include <sys/stat.h>
141 [[struct stat st1, st2;
142 if (close (creat ("conftest.file", 0600))) return 1;
143 if (stat ("conftest.file", &st1)) return 2;
145 if (chown ("conftest.file", st1.st_uid, st1.st_gid)) return 3;
146 if (stat ("conftest.file", &st2)) return 4;
147 if (st2.st_ctime <= st1.st_ctime) return 5;
149 [gl_cv_func_chown_ctime_works=yes],
150 [gl_cv_func_chown_ctime_works=no],
152 # Guess yes on glibc systems.
153 *-gnu*) gl_cv_func_chown_ctime_works="guessing yes" ;;
154 # Guess yes on musl systems.
155 *-musl*) gl_cv_func_chown_ctime_works="guessing yes" ;;
156 # If we don't know, obey --enable-cross-guesses.
157 *) gl_cv_func_chown_ctime_works="$gl_cross_guess_normal" ;;
160 rm -f conftest.file])
161 case "$gl_cv_func_chown_ctime_works" in
164 AC_DEFINE([CHOWN_CHANGE_TIME_BUG], [1], [Define to 1 if chown fails
165 to change ctime when at least one argument was not -1.])
172 # Determine whether chown follows symlinks (it should).
173 AC_DEFUN_ONCE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
176 [whether chown dereferences symlinks],
177 [gl_cv_func_chown_follows_symlink],
179 AC_RUN_IFELSE([AC_LANG_SOURCE([[
188 char const *dangling_symlink = "conftest.dangle";
190 unlink (dangling_symlink);
191 if (symlink ("conftest.no-such", dangling_symlink))
194 /* Exit successfully on a conforming system,
195 i.e., where chown must fail with ENOENT. */
196 if (chown (dangling_symlink, getuid (), getgid ()) == 0)
203 [gl_cv_func_chown_follows_symlink=yes],
204 [gl_cv_func_chown_follows_symlink=no],
205 [gl_cv_func_chown_follows_symlink="guessing yes"]
210 case "$gl_cv_func_chown_follows_symlink" in
213 AC_DEFINE([CHOWN_MODIFIES_SYMLINK], [1],
214 [Define if chown modifies symlinks.])