1#serial 17
2# Determine whether we need the chown wrapper.
3
4dnl Copyright (C) 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005, 2007 Free
5dnl Software Foundation, Inc.
6
7dnl This file is free software; the Free Software Foundation
8dnl gives unlimited permission to copy and/or distribute it,
9dnl with or without modifications, as long as this notice is preserved.
10
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
13# function.
14
15# From Jim Meyering.
16
17AC_DEFUN([gl_FUNC_CHOWN],
18[
19  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
20  AC_REQUIRE([AC_TYPE_UID_T])
21  AC_REQUIRE([AC_FUNC_CHOWN])
22  AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
23
24  if test $ac_cv_func_chown_works = no; then
25    AC_DEFINE(CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE, 1,
26      [Define if chown is not POSIX compliant regarding IDs of -1.])
27  fi
28
29  # If chown has either of the above problems, then we need the wrapper.
30  if test $ac_cv_func_chown_works$gl_cv_func_chown_follows_symlink = yesyes; then
31    : # no wrapper needed
32  else
33    REPLACE_CHOWN=1
34    AC_LIBOBJ(chown)
35    gl_PREREQ_CHOWN
36  fi
37])
38
39# Determine whether chown follows symlinks (it should).
40AC_DEFUN([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
41[
42  AC_CACHE_CHECK(
43    [whether chown(2) dereferences symlinks],
44    gl_cv_func_chown_follows_symlink,
45    [
46      AC_RUN_IFELSE([AC_LANG_SOURCE([[
47#include <unistd.h>
48#include <stdlib.h>
49#include <errno.h>
50
51	int
52	main ()
53	{
54	  char const *dangling_symlink = "conftest.dangle";
55
56	  unlink (dangling_symlink);
57	  if (symlink ("conftest.no-such", dangling_symlink))
58	    abort ();
59
60	  /* Exit successfully on a conforming system,
61	     i.e., where chown must fail with ENOENT.  */
62	  exit ( ! (chown (dangling_symlink, getuid (), getgid ()) != 0
63		    && errno == ENOENT));
64	}
65	]])],
66	[gl_cv_func_chown_follows_symlink=yes],
67	[gl_cv_func_chown_follows_symlink=no],
68	[gl_cv_func_chown_follows_symlink=yes]
69      )
70    ]
71  )
72
73  if test $gl_cv_func_chown_follows_symlink = no; then
74    AC_DEFINE(CHOWN_MODIFIES_SYMLINK, 1,
75      [Define if chown modifies symlinks.])
76  fi
77])
78
79# Prerequisites of lib/chown.c.
80AC_DEFUN([gl_PREREQ_CHOWN],
81[
82  AC_CHECK_FUNC([fchown], , [AC_LIBOBJ(fchown-stub)])
83])
84