2 # Determine whether we need the chown wrapper.
4 dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2020 Free Software
7 dnl This file is free software; the Free Software Foundation
8 dnl gives unlimited permission to copy and/or distribute it,
9 dnl with or without modifications, as long as this notice is preserved.
11 # chown should accept arguments of -1 for uid and gid, and it should
12 # dereference symlinks. If it doesn't, arrange to use the replacement
17 # This is taken from the following Autoconf patch:
18 # https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=7fbb553727ed7e0e689a17594b58559ecf3ea6e9
19 AC_DEFUN([AC_FUNC_CHOWN],
21 AC_REQUIRE([AC_TYPE_UID_T])dnl
22 AC_REQUIRE([AC_CANONICAL_HOST])dnl for cross-compiles
23 AC_CHECK_HEADERS([unistd.h])
24 AC_CACHE_CHECK([for working chown],
25 [ac_cv_func_chown_works],
32 char *f = "conftest.chown";
33 struct stat before, after;
35 if (creat (f, 0600) < 0)
37 if (stat (f, &before) < 0)
39 if (chown (f, (uid_t) -1, (gid_t) -1) == -1)
41 if (stat (f, &after) < 0)
43 return ! (before.st_uid == after.st_uid && before.st_gid == after.st_gid);
46 [ac_cv_func_chown_works=yes],
47 [ac_cv_func_chown_works=no],
48 [case "$host_os" in # ((
49 # Guess yes on Linux systems.
50 linux-* | linux) ac_cv_func_chown_works="guessing yes" ;;
51 # Guess yes on glibc systems.
52 *-gnu* | gnu*) ac_cv_func_chown_works="guessing yes" ;;
53 # Guess no on native Windows.
54 mingw*) ac_cv_func_chown_works="guessing no" ;;
55 # If we don't know, obey --enable-cross-guesses.
56 *) ac_cv_func_chown_works="$gl_cross_guess_normal" ;;
61 case "$ac_cv_func_chown_works" in
63 AC_DEFINE([HAVE_CHOWN], [1],
64 [Define to 1 if your system has a working `chown' function.])
69 AC_DEFUN_ONCE([gl_FUNC_CHOWN],
71 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
72 AC_REQUIRE([AC_TYPE_UID_T])
73 AC_REQUIRE([AC_FUNC_CHOWN])
74 AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
75 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
76 AC_CHECK_FUNCS_ONCE([chown fchown])
78 dnl mingw lacks chown altogether.
79 if test $ac_cv_func_chown = no; then
82 dnl Some old systems treated chown like lchown.
83 case "$gl_cv_func_chown_follows_symlink" in
88 dnl Some old systems tried to use uid/gid -1 literally.
89 case "$ac_cv_func_chown_works" in
91 AC_DEFINE([CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE], [1],
92 [Define if chown is not POSIX compliant regarding IDs of -1.])
97 dnl Solaris 9 ignores trailing slash.
98 dnl FreeBSD 7.2 mishandles trailing slash on symlinks.
99 dnl Likewise for AIX 7.1.
100 AC_CACHE_CHECK([whether chown honors trailing slash],
101 [gl_cv_func_chown_slash_works],
102 [touch conftest.file && rm -f conftest.link
103 AC_RUN_IFELSE([AC_LANG_PROGRAM([[
107 ]], [[ if (symlink ("conftest.file", "conftest.link")) return 1;
108 if (chown ("conftest.link/", getuid (), getgid ()) == 0) return 2;
110 [gl_cv_func_chown_slash_works=yes],
111 [gl_cv_func_chown_slash_works=no],
113 # Guess yes on glibc systems.
114 *-gnu*) gl_cv_func_chown_slash_works="guessing yes" ;;
115 # Guess yes on musl systems.
116 *-musl*) gl_cv_func_chown_slash_works="guessing yes" ;;
117 # If we don't know, obey --enable-cross-guesses.
118 *) gl_cv_func_chown_slash_works="$gl_cross_guess_normal" ;;
121 rm -f conftest.link conftest.file])
122 case "$gl_cv_func_chown_slash_works" in
125 AC_DEFINE([CHOWN_TRAILING_SLASH_BUG], [1],
126 [Define to 1 if chown mishandles trailing slash.])
131 dnl OpenBSD fails to update ctime if ownership does not change.
132 AC_CACHE_CHECK([whether chown always updates ctime],
133 [gl_cv_func_chown_ctime_works],
134 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
139 #include <sys/stat.h>
140 ]], [[ struct stat st1, st2;
141 if (close (creat ("conftest.file", 0600))) return 1;
142 if (stat ("conftest.file", &st1)) return 2;
144 if (chown ("conftest.file", st1.st_uid, st1.st_gid)) return 3;
145 if (stat ("conftest.file", &st2)) return 4;
146 if (st2.st_ctime <= st1.st_ctime) return 5;
148 [gl_cv_func_chown_ctime_works=yes],
149 [gl_cv_func_chown_ctime_works=no],
151 # Guess yes on glibc systems.
152 *-gnu*) gl_cv_func_chown_ctime_works="guessing yes" ;;
153 # Guess yes on musl systems.
154 *-musl*) gl_cv_func_chown_ctime_works="guessing yes" ;;
155 # If we don't know, obey --enable-cross-guesses.
156 *) gl_cv_func_chown_ctime_works="$gl_cross_guess_normal" ;;
159 rm -f conftest.file])
160 case "$gl_cv_func_chown_ctime_works" in
163 AC_DEFINE([CHOWN_CHANGE_TIME_BUG], [1], [Define to 1 if chown fails
164 to change ctime when at least one argument was not -1.])
171 # Determine whether chown follows symlinks (it should).
172 AC_DEFUN_ONCE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
175 [whether chown dereferences symlinks],
176 [gl_cv_func_chown_follows_symlink],
178 AC_RUN_IFELSE([AC_LANG_SOURCE([[
187 char const *dangling_symlink = "conftest.dangle";
189 unlink (dangling_symlink);
190 if (symlink ("conftest.no-such", dangling_symlink))
193 /* Exit successfully on a conforming system,
194 i.e., where chown must fail with ENOENT. */
195 if (chown (dangling_symlink, getuid (), getgid ()) == 0)
202 [gl_cv_func_chown_follows_symlink=yes],
203 [gl_cv_func_chown_follows_symlink=no],
204 [gl_cv_func_chown_follows_symlink="guessing yes"]
209 case "$gl_cv_func_chown_follows_symlink" in
212 AC_DEFINE([CHOWN_MODIFIES_SYMLINK], [1],
213 [Define if chown modifies symlinks.])