new file, from Paul Eggert

lib/posixver.c

@@ -0,0 +1,58 @@
+/* Which POSIX version to conform to, for utilities.
+
+   Copyright (C) 2002 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU Library General Public License as published
+   by the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+   USA.  */
+
+/* Written by Paul Eggert.  */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <limits.h>
+
+#include <stdlib.h>
+#if !HAVE_DECL_GETENV && !defined getenv
+char *getenv ();
+#endif
+
+#if HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+#ifndef _POSIX2_VERSION
+# define _POSIX2_VERSION 0
+#endif
+
+/* The POSIX version that utilities should conform to.  The default is
+   specified by the system.  */
+
+int
+posix2_version (void)
+{
+  long int v = _POSIX2_VERSION;
+  char const *s = getenv ("_POSIX2_VERSION");
+
+  if (s && *s)
+    {
+      char *e;
+      long int i = strtol (s, &e, 10);
+      if (! *e)
+	v = i;
+    }
+
+  return v < INT_MIN ? INT_MIN : v < INT_MAX ? v : INT_MAX;
+}

lib/posixver.h

@@ -0,0 +1 @@
+int posix2_version (void);