Merge pull request #1898 from owncloud/session_start_fix

set http 500 when session could not be started to prevent serving of emp...

lib/base.php

@@ -320,8 +320,21 @@ class OC {
 		// set the session name to the instance id - which is unique
 		session_name(OC_Util::getInstanceId());
 
-		// (re)-initialize session
-		session_start();
+		// if session cant be started break with http 500 error
+		if (session_start() === false){
+			OC_Log::write('core', 'Session could not be initialized', 
+				OC_Log::ERROR);
+			
+			header('HTTP/1.1 500 Internal Server Error');
+			$error = 'Session could not be initialized. Please contact your ';
+			$error .= 'system administrator';
+
+			$tmpl = new OC_Template('', 'error', 'guest');
+			$tmpl->assign('errors', array(1 => array('error' => $error)));
+			$tmpl->printPage();
+
+			exit();
+		}
 
 		// regenerate session id periodically to avoid session fixation
 		if (!isset($_SESSION['SID_CREATED'])) {