setenv: relax requirement in light of POSIX ruling

Requiring that {un,}setenv gracefully reject NULL is just a waste
of processing power; POSIX agreed to this argument in
 http://austingroupbugs.net/view.php?id=185
so we no longer worry whether a native implementation handles NULL.

* m4/setenv.m4 (gl_FUNC_SETENV_SEPARATE): Test handling of "" but
not NULL.
* tests/test-setenv.c (main): Relax test.
* tests/test-unsetenv.c (main): Likewise.
* doc/posix-functions/setenv.texi (setenv): Document this.
* doc/posix-functions/unsetenv.texi (unsetenv): Likewise.

Signed-off-by: Eric Blake <ebb9@byu.net>

6 files changed, 30 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 99a631c916..7aaf2de3b2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2009-12-11  Eric Blake  <ebb9@byu.net>
+
+	setenv: relax requirement in light of POSIX ruling
+	* m4/setenv.m4 (gl_FUNC_SETENV_SEPARATE): Test handling of "" but
+	not NULL.
+	* tests/test-setenv.c (main): Relax test.
+	* tests/test-unsetenv.c (main): Likewise.
+	* doc/posix-functions/setenv.texi (setenv): Document this.
+	* doc/posix-functions/unsetenv.texi (unsetenv): Likewise.
+
 2009-12-11  Bruno Haible  <bruno@clisp.org>
 
 	New module 'fd-safer-flag'.
diff --git a/doc/posix-functions/setenv.texi b/doc/posix-functions/setenv.texi
index 87c9e2d7cc..279ae14a54 100644
--- a/doc/posix-functions/setenv.texi
+++ b/doc/posix-functions/setenv.texi
@@ -13,7 +13,7 @@ This function is missing on some platforms:
 AIX 4.3.2, HP-UX 11, IRIX 6.5, Solaris 9, mingw, BeOS.
 @item
 On some platforms, this function does not fail with @samp{EINVAL} when
-passed a null pointer, an empty string, or a string containing @samp{=}:
+passed an empty string or a string containing @samp{=}:
 FreeBSD 6.0, NetBSD 1.6, OpenBSD 3.8, Cygwin 1.5.x.
 @item
 On some platforms, this function removes a leading @samp{=} from the
@@ -23,4 +23,8 @@ Cygwin 1.5.x.
 
 Portability problems not fixed by Gnulib:
 @itemize
+@item
+Older versions of POSIX required that @code{setenv(NULL,"",0)} gracefully
+fail with @code{EINVAL}, but not all implementations guarantee this,
+and the requirement was removed.
 @end itemize
diff --git a/doc/posix-functions/unsetenv.texi b/doc/posix-functions/unsetenv.texi
index 99a5e69527..80b17048cb 100644
--- a/doc/posix-functions/unsetenv.texi
+++ b/doc/posix-functions/unsetenv.texi
@@ -17,7 +17,7 @@ platforms:
 MacOS X 10.3, FreeBSD 6.0, NetBSD 1.6, OpenBSD 3.8, OSF/1 5.1.
 @item
 On some platforms, this function does not fail with @samp{EINVAL} when
-passed a null pointer, an empty string, or a string containing @samp{=}:
+passed an empty string or a string containing @samp{=}:
 FreeBSD 6.0, NetBSD 1.6, OpenBSD 3.8.
 @item
 This function removes only the first value association for the given
@@ -27,4 +27,8 @@ Solaris 10.
 
 Portability problems not fixed by Gnulib:
 @itemize
+@item
+Older versions of POSIX required that @code{unsetenv(NULL)} gracefully
+fail with @code{EINVAL}, but not all implementations guarantee this,
+and the requirement was removed.
 @end itemize
diff --git a/m4/setenv.m4 b/m4/setenv.m4
index a5df034aa6..29e6866742 100644
--- a/m4/setenv.m4
+++ b/m4/setenv.m4
@@ -1,4 +1,4 @@
-# setenv.m4 serial 13
+# setenv.m4 serial 14
 dnl Copyright (C) 2001-2004, 2006-2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -26,7 +26,7 @@ AC_DEFUN([gl_FUNC_SETENV_SEPARATE],
        #include <stdlib.h>
        #include <errno.h>
       ]], [[
-       if (setenv (NULL, "", 0) != -1) return 1;
+       if (setenv ("", "", 0) != -1) return 1;
        if (errno != EINVAL) return 2;
        if (setenv ("a", "=", 1) != 0) return 3;
        if (strcmp (getenv ("a"), "=") != 0) return 4;
diff --git a/tests/test-setenv.c b/tests/test-setenv.c
index 61be8381bc..eb1fe3336f 100644
--- a/tests/test-setenv.c
+++ b/tests/test-setenv.c
@@ -52,9 +52,13 @@ main (void)
   errno = 0;
   ASSERT (setenv ("a=b", "", 0) == -1);
   ASSERT (errno == EINVAL);
+#if 0
+  /* glibc and gnulib's implementation guarantee this, but POSIX no
+     longer requires it: http://austingroupbugs.net/view.php?id=185  */
   errno = 0;
   ASSERT (setenv (NULL, "", 0) == -1);
   ASSERT (errno == EINVAL);
+#endif
 
   return 0;
 }
diff --git a/tests/test-unsetenv.c b/tests/test-unsetenv.c
index 11af82c991..2815cf3a39 100644
--- a/tests/test-unsetenv.c
+++ b/tests/test-unsetenv.c
@@ -57,9 +57,13 @@ main (void)
   errno = 0;
   ASSERT (unsetenv ("a=b") == -1);
   ASSERT (errno == EINVAL);
+#if 0
+  /* glibc and gnulib's implementation guarantee this, but POSIX no
+     longer requires it: http://austingroupbugs.net/view.php?id=185  */
   errno = 0;
   ASSERT (unsetenv (NULL) == -1);
   ASSERT (errno == EINVAL);
+#endif
 
   return 0;
 }