Remove Wundef warnings for specification macros

This patch adds a file posix-conf-vars.list that is used to generate
macros to determine if a macro is defined as set, unset or not
defined.  gen-posix-conf-vars.awk processes this file and generates a
header (posix-conf-vars-def.h) with these macros.  A new header
posix-conf-vars.h includes this generated header and defines accessor
macros for the generated macros.

Tested on x86_64.

	* posix/Makefile (before-compile): Add posix-conf-vars-def.h.
	($(objpfx)posix-conf-vars-def.h): New target.
	* posix/posix-conf-vars.list: New file.
	* posix/posix-conf-vars.h: New file.
	* posix/confstr.c: Include posix-conf-vars.h.
	(confstr): Use CONF_IS_* macros.
	* posix/posix-envs.def: Include posix-conf-vars.h.  Use
	CONF_IS_* macros.
	* scripts/gen-posix-conf-vars.awk: New file.

1 files changed, 48 insertions, 0 deletions

diff --git a/posix/posix-conf-vars.h b/posix/posix-conf-vars.h
new file mode 100644
index 0000000000..6faf29f56b
--- /dev/null
+++ b/posix/posix-conf-vars.h
@@ -0,0 +1,48 @@
+/* Macros to check if a POSIX configuration variable is defined or set.
+
+   Copyright (C) 1991-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _POSIX_CONF_VARS_H
+#define _POSIX_CONF_VARS_H
+
+/* The script gen-posix-conf-vars.awk generates the header
+   posix-conf-vars-def.h from the list file posix-conf-vars.list and defines
+   CONF_DEF_* macros for each entry in the list file set to either of
+   CONF_DEF_UNDEFINED, CONF_DEF_DEFINED_SET or CONF_DEF_DEFINED_UNSET.  To
+   check configuration variables within glibc code, use the configuration macro
+   functions instead of checking for definitions of the macros.  */
+
+#include <posix-conf-vars-def.h>
+
+#define CONF_DEF_UNDEFINED	1
+#define CONF_DEF_DEFINED_SET	2
+#define CONF_DEF_DEFINED_UNSET	3
+
+/* The configuration variable is not defined.  */
+#define CONF_IS_UNDEFINED(conf) (CONF_DEF##conf == CONF_DEF_UNDEFINED)
+
+/* The configuration variable is defined.  It may or may not be set.  */
+#define CONF_IS_DEFINED(conf) (CONF_DEF##conf != CONF_DEF_UNDEFINED)
+
+/* The configuration variable is defined and set.  */
+#define CONF_IS_DEFINED_SET(conf) (CONF_DEF##conf == CONF_DEF_DEFINED_SET)
+
+/* The configuration variable is defined but not set.  */
+#define CONF_IS_DEFINED_UNSET(conf) (CONF_DEF##conf == CONF_DEF_DEFINED_UNSET)
+
+#endif