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(gl_PREREQ_CHOWN): Check for fcntl.h.

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See if we need an fchown replacement.
(gl_FUNC_CHOWN_FOLLOWS_SYMLINK): New macro.
(gl_FUNC_CHOWN): Require gl_FUNC_CHOWN_FOLLOWS_SYMLINK,
and use the replacement function if we detect either defect.
This commit is contained in:
Jim Meyering
2004-05-01 14:41:21 +00:00
parent 87cb7bca64
commit 1c473ba843
1 changed files with 61 additions and 9 deletions
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m4/chown.m4
+61 -9
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@@ -1,15 +1,24 @@
#serial 9
dnl From Jim Meyering.
dnl Determine whether chown accepts arguments of -1 for uid and gid.
dnl If it doesn't, arrange to use the replacement function.
dnl
#serial 10
# 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.
AC_DEFUN([gl_FUNC_CHOWN],
[
AC_REQUIRE([AC_TYPE_UID_T])dnl
AC_REQUIRE([AC_TYPE_UID_T])
AC_REQUIRE([AC_FUNC_CHOWN])
if test $ac_cv_func_chown_works = no; then
AC_REQUIRE([gl_FUNC_CHOWN_FOLLOWS_SYMLINK])
if test $ac_cv_func_chown_works = yes; then
AC_DEFINE(CHOWN_FAILS_TO_HONOR_ID_OF_NEGATIVE_ONE, 1,
[Define if chown is not POSIX compliant regarding IDs of -1.])
fi
# If chown has either of the above problems, then we need the wrapper.
if test $ac_cv_func_chown_works$gl_cv_func_chown_follows_symlink = yesyes; then
: # no wrapper needed
else
AC_LIBOBJ(chown)
AC_DEFINE(chown, rpl_chown,
[Define to rpl_chown if the replacement function should be used.])
@@ -17,8 +26,51 @@ AC_DEFUN([gl_FUNC_CHOWN],
fi
])
# Determine whether chown follows symlinks (it should).
AC_DEFUN([gl_FUNC_CHOWN_FOLLOWS_SYMLINK],
[
AC_CACHE_CHECK(
[whether chown(2) dereferences symlinks],
gl_cv_func_chown_follows_symlink,
[
AC_RUN_IFELSE([AC_LANG_SOURCE([[
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <stdlib.h>
#include <errno.h>
int
main ()
{
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. */
exit ( ! (chown (dangling_symlink, getuid (), getgid ()) != 0
&& errno == ENOENT));
}
]])],
[gl_cv_func_chown_follows_symlink=yes],
[gl_cv_func_chown_follows_symlink=no],
[gl_cv_func_chown_follows_symlink=no]
)
]
)
if test $gl_cv_func_chown_follows_symlink = no; then
AC_DEFINE(CHOWN_MODIFIES_SYMLINK, 1,
[Define if chown modifies symlinks.])
fi
])
# Prerequisites of lib/chown.c.
AC_DEFUN([gl_PREREQ_CHOWN],
[
AC_CHECK_HEADERS_ONCE(unistd.h)
AC_CHECK_HEADERS_ONCE(unistd.h fcntl.h)
AC_CHECK_FUNC([fchown], , [AC_LIBOBJ(fchown-stub)])
])