openat-safer: new module * modules/openat-safer: New file. * lib/openat-safer.c: Likewise. * m4/fcntl-safer.m4 (gl_OPENAT_SAFER): New macro. * lib/fcntl-safer.h (openat_safer): Declare. * lib/fcntl--.h (openat): Override. * MODULES.html.sh (File descriptor based I/O): Mention it. * lib/openat.h: Add double-inclusion guards. * lib/openat.c (includes): Only include "fcntl-safer.h", not "fcntl--.h", so we can implement openat. * modules/openat-safer-tests: New test. * tests/test-openat-safer.c: New file. Signed-off-by: Eric Blake <ebb9@byu.net>

--- a/m4/fcntl-safer.m4
+++ b/m4/fcntl-safer.m4
@@ -1,4 +1,4 @@
-#serial 6
+#serial 7
 dnl Copyright (C) 2005-2007, 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,
@@ -11,3 +11,9 @@
   # Prerequisites of lib/open-safer.c.
   AC_REQUIRE([gl_PROMOTED_TYPE_MODE_T])
 ])
+
+AC_DEFUN([gl_OPENAT_SAFER],
+[
+  AC_REQUIRE([gl_FCNTL_SAFER])
+  AC_LIBOBJ([openat-safer])
+])