2 # Determine whether we need the chown wrapper.
4 dnl Copyright (C) 1997-2001, 2003-2005, 2007, 2009-2017 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 "$host_os" in # ((
49 # Guess yes on glibc systems.
50 *-gnu*) ac_cv_func_chown_works="guessing yes" ;;
51 # Guess no on native Windows.
52 mingw*) ac_cv_func_chown_works="guessing no" ;;
53 # If we don't know, assume the worst.
54 *) ac_cv_func_chown_works="guessing no" ;;
59 case "$ac_cv_func_chown_works" in
61 AC_DEFINE([HAVE_CHOWN], [1],
62 [Define to 1 if your system has a working `chown' function.])
67 AC_DEFUN_ONCE([gl_FUNC_CHOWN],
69 AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
70 AC_REQUIRE([AC_TYPE_UID_T])
71 AC_REQUIRE([AC_FUNC_CHOWN])
72 AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
73 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
74 AC_CHECK_FUNCS_ONCE([chown fchown])
76 dnl mingw lacks chown altogether.
77 if test $ac_cv_func_chown = no; then
80 dnl Some old systems treated chown like lchown.
81 if test $gl_cv_func_chown_follows_symlink = no; then
85 dnl Some old systems tried to use uid/gid -1 literally.
86 case "$ac_cv_func_chown_works" in
88 AC_DEFINE([CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE], [1],
89 [Define if chown is not POSIX compliant regarding IDs of -1.])
94 dnl Solaris 9 ignores trailing slash.
95 dnl FreeBSD 7.2 mishandles trailing slash on symlinks.
96 dnl Likewise for AIX 7.1.
97 AC_CACHE_CHECK([whether chown honors trailing slash],
98 [gl_cv_func_chown_slash_works],
99 [touch conftest.file && rm -f conftest.link
100 AC_RUN_IFELSE([AC_LANG_PROGRAM([[
104 ]], [[ if (symlink ("conftest.file", "conftest.link")) return 1;
105 if (chown ("conftest.link/", getuid (), getgid ()) == 0) return 2;
107 [gl_cv_func_chown_slash_works=yes],
108 [gl_cv_func_chown_slash_works=no],
110 # Guess yes on glibc systems.
111 *-gnu*) gl_cv_func_chown_slash_works="guessing yes" ;;
112 # If we don't know, assume the worst.
113 *) gl_cv_func_chown_slash_works="guessing no" ;;
116 rm -f conftest.link conftest.file])
117 case "$gl_cv_func_chown_slash_works" in
120 AC_DEFINE([CHOWN_TRAILING_SLASH_BUG], [1],
121 [Define to 1 if chown mishandles trailing slash.])
126 dnl OpenBSD fails to update ctime if ownership does not change.
127 AC_CACHE_CHECK([whether chown always updates ctime],
128 [gl_cv_func_chown_ctime_works],
129 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
134 #include <sys/stat.h>
135 ]], [[ struct stat st1, st2;
136 if (close (creat ("conftest.file", 0600))) return 1;
137 if (stat ("conftest.file", &st1)) return 2;
139 if (chown ("conftest.file", st1.st_uid, st1.st_gid)) return 3;
140 if (stat ("conftest.file", &st2)) return 4;
141 if (st2.st_ctime <= st1.st_ctime) return 5;
143 [gl_cv_func_chown_ctime_works=yes],
144 [gl_cv_func_chown_ctime_works=no],
146 # Guess yes on glibc systems.
147 *-gnu*) gl_cv_func_chown_ctime_works="guessing yes" ;;
148 # If we don't know, assume the worst.
149 *) gl_cv_func_chown_ctime_works="guessing no" ;;
152 rm -f conftest.file])
153 case "$gl_cv_func_chown_ctime_works" in
156 AC_DEFINE([CHOWN_CHANGE_TIME_BUG], [1], [Define to 1 if chown fails
157 to change ctime when at least one argument was not -1.])
164 # Determine whether chown follows symlinks (it should).
165 AC_DEFUN_ONCE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
168 [whether chown dereferences symlinks],
169 [gl_cv_func_chown_follows_symlink],
171 AC_RUN_IFELSE([AC_LANG_SOURCE([[
180 char const *dangling_symlink = "conftest.dangle";
182 unlink (dangling_symlink);
183 if (symlink ("conftest.no-such", dangling_symlink))
186 /* Exit successfully on a conforming system,
187 i.e., where chown must fail with ENOENT. */
188 if (chown (dangling_symlink, getuid (), getgid ()) == 0)
195 [gl_cv_func_chown_follows_symlink=yes],
196 [gl_cv_func_chown_follows_symlink=no],
197 [gl_cv_func_chown_follows_symlink=yes]
202 if test $gl_cv_func_chown_follows_symlink = no; then
203 AC_DEFINE([CHOWN_MODIFIES_SYMLINK], [1],
204 [Define if chown modifies symlinks.])