maint.mk: import changes to syntax-check macros from coreutils

[gnulib.git] / m4 / openat.m4

diff --git a/m4/openat.m4 b/m4/openat.m4
index 27b0e59..10eac5c 100644 (file)
--- a/m4/openat.m4
+++ b/m4/openat.m4
@@ -1,7 +1,7 @@
-#serial 3
-# See if we need to use our replacement for Solaris' openat function.
+# serial 17
+# See if we need to use our replacement for Solaris' openat et al functions.
 
-dnl Copyright (C) 2004 Free Software Foundation, Inc.
+dnl Copyright (C) 2004-2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -10,19 +10,82 @@ dnl with or without modifications, as long as this notice is preserved.
 
 AC_DEFUN([gl_FUNC_OPENAT],
 [
-  AC_LIBSOURCES([openat.c, openat.h])
+  AC_LIBOBJ([openat-proc])
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
-  AC_REPLACE_FUNCS(openat)
-  case $ac_cv_func_openat in
-  yes) ;;
+  AC_CHECK_FUNCS_ONCE([lchmod])
+  AC_CHECK_FUNCS_ONCE([fdopendir])
+  AC_REPLACE_FUNCS([fchmodat mkdirat openat])
+  AC_REQUIRE([AC_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
+  case $ac_cv_func_openat+$ac_cv_func_lstat_dereferences_slashed_symlink in
+  yes+yes) ;;
+  yes+*) AC_LIBOBJ([fstatat]);;
   *)
     AC_DEFINE([__OPENAT_PREFIX], [[rpl_]],
       [Define to rpl_ if the openat replacement function should be used.])
     gl_PREREQ_OPENAT;;
   esac
+  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
 ])
 
 AC_DEFUN([gl_PREREQ_OPENAT],
 [
-  AC_REQUIRE([gl_SAVE_CWD])
+  :
 ])