+ gl_FUNC_FCHOWNAT
+])
+
+# gl_FUNC_FCHOWNAT_DEREF_BUG([ACTION-IF-BUGGY[, ACTION-IF-NOT_BUGGY]])
+AC_DEFUN([gl_FUNC_FCHOWNAT_DEREF_BUG],
+[
+ AC_CACHE_CHECK([whether fchownat works with AT_SYMLINK_NOFOLLOW],
+ gl_cv_func_fchownat_nofollow_works,
+ [
+ gl_dangle=conftest.dangle
+ # Remove any remnants of a previous test.
+ rm -f $gl_dangle
+ # Arrange for deletion of the temporary file this test creates.
+ ac_clean_files="$ac_clean_files $gl_dangle"
+ ln -s conftest.no-such $gl_dangle
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE(
+ [[
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/types.h>
+int
+main ()
+{
+ return (fchownat (AT_FDCWD, "$gl_dangle", -1, getgid (),
+ AT_SYMLINK_NOFOLLOW) != 0
+ && errno == ENOENT);
+}
+ ]])],
+ [gl_cv_func_fchownat_nofollow_works=yes],
+ [gl_cv_func_fchownat_nofollow_works=no],
+ [gl_cv_func_fchownat_nofollow_works=no],
+ )
+ ])
+ AS_IF([test $gl_cv_func_fchownat_nofollow_works = no], [$1], [$2])
+])
+
+# If we have the fchownat function, and it has the bug (in glibc-2.4)
+# that it dereferences symlinks even with AT_SYMLINK_NOFOLLOW, then
+# use the replacement function.
+# Also use the replacement function if fchownat is simply not available.
+AC_DEFUN([gl_FUNC_FCHOWNAT],
+[
+ # Assume we'll use the replacement function.
+ # The only case in which we won't is when we have fchownat, and it works.
+ use_replacement_fchownat=yes
+
+ AC_CHECK_FUNC([fchownat], [have_fchownat=yes], [have_fchownat=no])
+ if test $have_fchownat = yes; then
+ gl_FUNC_FCHOWNAT_DEREF_BUG([], [use_replacement_fchownat=no])
+ fi
+
+ if test $use_replacement_fchownat = yes; then
+ AC_LIBOBJ(fchownat)
+ AC_DEFINE(fchownat, rpl_fchownat,
+ [Define to rpl_fchownat if the replacement function should be used.])
+ fi