login: fix login_is_valid test

1 files changed, 22 insertions, 1 deletions

diff --git a/src/login/login-shared.c b/src/login/login-shared.c
index ff13c28861..054c77503b 100644
--- a/src/login/login-shared.c
+++ b/src/login/login-shared.c
@@ -1,8 +1,29 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Zbigniew Jędrzejewski-Szmek
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
 #include "login-shared.h"
 #include "def.h"
 
 bool session_id_valid(const char *id) {
         assert(id);
 
-        return id + strspn(id, LETTERS DIGITS) == '\0';
+        return id[0] && id[strspn(id, LETTERS DIGITS)] == '\0';
 }