setenv, unsetenv: work around various bugs POSIX requires setenv(NULL,"",0), setenv("a=b","",0), unsetenv(NULL), and unsetenv("a=b") to fail with EINVAL, but many BSD implementations lack validation. The gnulib replacement for void unsetenv did not do validation, and the replacement for setenv was out of sync with glibc. Also, some BSD implementations of setenv("a","==",1) eat the leading '='. See also some recent Austin Group interpretations on environ: http://austingroupbugs.net/view.php?id=167 http://austingroupbugs.net/view.php?id=185 * lib/setenv.c (setenv) [!HAVE_SETENV]: Resync from glibc. (setenv) [HAVE_SETENV]: Work around bugs. * lib/unsetenv.c (unsetenv) [HAVE_UNSETENV]: Work around bugs. * m4/setenv.m4 (gl_FUNC_SETENV_SEPARATE, gl_FUNC_UNSETENV): Check for bugs. (gl_FUNC_SETENV): Write in terms of gl_FUNC_SETENV_SEPARATE. * m4/environ.m4 (gl_ENVIRON): Avoid expand-before-require. * m4/stdlib_h.m4 (gl_STDLIB_H_DEFAULTS): Update defaults. * modules/stdlib (Makefile.am): Update substitutions. * lib/stdlib.in.h (setenv, unsetenv): Update prototypes. * doc/posix-functions/setenv.texi (setenv): Document the bugs. * doc/posix-functions/unsetenv.texi (unsetenv): Likewise. * modules/setenv-tests: New test. * modules/unsetenv-tests: Likewise. * tests/test-setenv.c: New file. * tests/test-unsetenv.c: Likewise. Signed-off-by: Eric Blake <ebb9@byu.net>

--- a/lib/unsetenv.c
+++ b/lib/unsetenv.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1992,1995-1999,2000-2002,2005-2008 Free Software Foundation, Inc.
+/* Copyright (C) 1992,1995-1999,2000-2002,2005-2009 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    This program is free software: you can redistribute it and/or modify
@@ -47,6 +47,7 @@
 # define unsetenv __unsetenv
 #endif
 
+#if _LIBC || !HAVE_UNSETENV
 
 int
 unsetenv (const char *name)
@@ -88,3 +89,27 @@
 # undef unsetenv
 weak_alias (__unsetenv, unsetenv)
 #endif
+
+#else /* HAVE_UNSETENV */
+
+# undef unsetenv
+
+/* Call the underlying unsetenv, in case there is hidden bookkeeping
+   that needs updating beyond just modifying environ.  */
+int
+rpl_unsetenv (const char *name)
+{
+  int result = 0;
+  if (!name || !*name || strchr (name, '='))
+    {
+      errno = EINVAL;
+      return -1;
+    }
+# if !VOID_UNSETENV
+  result =
+# endif
+    unsetenv (name);
+  return result;
+}
+
+#endif /* HAVE_UNSETENV */