Make setenv(3) consistent with unsetenv(3), giving EINVAL if passed

an empty name, NULL pointer, or a name containing an '=' character.
OK millert@, guenther@

src/lib/libc/stdlib/getenv.3

@@ -29,9 +29,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: getenv.3,v 1.17 2012/06/02 00:14:16 guenther Exp $
+.\"	$OpenBSD: getenv.3,v 1.18 2012/09/23 16:08:04 jeremy Exp $
 .\"
-.Dd $Mdocdate: June 2 2012 $
+.Dd $Mdocdate: September 23 2012 $
 .Dt GETENV 3
 .Os
 .Sh NAME
@@ -53,14 +53,6 @@
 .Sh DESCRIPTION
 These functions set, unset, and fetch environment variables from the host
 .Em environment list .
-For compatibility with differing environment conventions, the given argument
-.Fa name
-may be appended with an equal sign
-.Dq Li \&=
-followed by zero or more characters,
-and
-.Fa value
-may be prepended with an equal sign.
 .Pp
 The
 .Fn getenv
@@ -125,19 +117,15 @@ The
 .Fn setenv
 or
 .Fn unsetenv
-function was passed a
+function was passed an empty
+.Ar name
+or a NULL pointer, or was passed a
 .Ar name
 containing an
 .Sq =
 character.
 .Pp
 The
-.Fn unsetenv
-function was passed an empty
-.Ar name
-or a NULL pointer.
-.Pp
-The
 .Fn putenv
 function was passed a
 .Ar string

src/lib/libc/stdlib/setenv.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: setenv.c,v 1.13 2010/08/23 22:31:50 millert Exp $ */
+/*	$OpenBSD: setenv.c,v 1.14 2012/09/23 16:08:04 jeremy Exp $ */
 /*
  * Copyright (c) 1987 Regents of the University of California.
  * All rights reserved.
@@ -94,14 +94,16 @@ setenv(const char *name, const char *value, int rewrite)
 	const char *np;
 	int l_value, offset = 0;
 
+	if (!name || !*name) {
+		errno = EINVAL;
+		return (-1);
+	}
 	for (np = name; *np && *np != '='; ++np)
 		;
-#ifdef notyet
 	if (*np) {
 		errno = EINVAL;
 		return (-1);			/* has `=' in name */
 	}
-#endif
 
 	l_value = strlen(value);
 	if ((C = __findenv(name, (int)(np - name), &offset)) != NULL) {