Throw an exception when login is canceled by an app

lib/base.php

@@ -844,19 +844,24 @@ class OC {
 	protected static function handleLogin() {
 		OC_App::loadApps(array('prelogin'));
 		$error = array();
+		$messages = [];
 
-		// auth possible via apache module?
+		try {
-		if (OC::tryApacheAuth()) {
+			// auth possible via apache module?
-			$error[] = 'apacheauthfailed';
+			if (OC::tryApacheAuth()) {
-		} // remember was checked after last login
+				$error[] = 'apacheauthfailed';
-		elseif (OC::tryRememberLogin()) {
+			} // remember was checked after last login
-			$error[] = 'invalidcookie';
+			elseif (OC::tryRememberLogin()) {
-		} // logon via web form
+				$error[] = 'invalidcookie';
-		elseif (OC::tryFormLogin()) {
+			} // logon via web form
-			$error[] = 'invalidpassword';
+			elseif (OC::tryFormLogin()) {
+				$error[] = 'invalidpassword';
+			}
+		} catch (\OC\User\LoginException $e) {
+			$messages[] = $e->getMessage();
 		}
 
-		OC_Util::displayLoginPage(array_unique($error));
+		OC_Util::displayLoginPage(array_unique($error), $messages);
 	}
 
 	/**

lib/private/user/loginexception.php

@@ -0,0 +1,12 @@
+<?php
+/**
+ * Copyright (c) 2014 Robin Appelman <icewind@owncloud.com>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+namespace OC\User;
+
+class LoginException extends \Exception {
+}

lib/private/user/session.php

@@ -189,6 +189,7 @@ class Session implements IUserSession, Emitter {
 	 * @param string $uid
 	 * @param string $password
 	 * @return boolean|null
+	 * @throws LoginException
 	 */
 	public function login($uid, $password) {
 		$this->manager->emit('\OC\User', 'preLogin', array($uid, $password));
@@ -199,7 +200,11 @@ class Session implements IUserSession, Emitter {
 					$this->setUser($user);
 					$this->setLoginName($uid);
 					$this->manager->emit('\OC\User', 'postLogin', array($user, $password));
-					return $this->isLoggedIn();
+					if ($this->isLoggedIn()) {
+						return true;
+					} else {
+						throw new LoginException('Login canceled by app');
+					}
 				} else {
 					return false;
 				}