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/modules/stdlib	Mon Nov 16 22:08:52 2009 +0100
+++ b/modules/stdlib	Sat Nov 14 22:13:10 2009 -0700
@@ -73,8 +73,9 @@
 	      -e 's|@''REPLACE_MKSTEMP''@|$(REPLACE_MKSTEMP)|g' \
 	      -e 's|@''REPLACE_PUTENV''@|$(REPLACE_PUTENV)|g' \
 	      -e 's|@''REPLACE_REALPATH''@|$(REPLACE_REALPATH)|g' \
+	      -e 's|@''REPLACE_SETENV''@|$(REPLACE_SETENV)|g' \
 	      -e 's|@''REPLACE_STRTOD''@|$(REPLACE_STRTOD)|g' \
-	      -e 's|@''VOID_UNSETENV''@|$(VOID_UNSETENV)|g' \
+	      -e 's|@''REPLACE_UNSETENV''@|$(REPLACE_UNSETENV)|g' \
 	      -e '/definition of GL_LINK_WARNING/r $(LINK_WARNING_H)' \
 	      < $(srcdir)/stdlib.in.h; \
 	} > $@-t && \