check registered sections and settings after an app got updated to garbage collect orphaned classes

lib/base.php

@@ -810,6 +810,14 @@ class OC {
 			/** @var \OCP\App\ManagerEvent $event */
 			\OC::$server->getSettingsManager()->onAppDisabled($event->getAppID());
 		});
+		$dispatcher->addListener(OCP\App\ManagerEvent::EVENT_APP_UPDATE, function($event) {
+			/** @var \OCP\App\ManagerEvent $event */
+			$jobList = \OC::$server->getJobList();
+			$job = 'OC\\Settings\\RemoveOrphaned';
+			if(!($jobList->has($job, null))) {
+				$jobList->add($job);
+			}
+		});
 	}
 
 	private static function registerEncryptionWrapper() {

lib/private/Settings/Manager.php

@@ -112,6 +112,37 @@ class Manager implements IManager {
 		}
 	}
 
+	public function checkForOrphanedClassNames() {
+		$tables = [ self::TABLE_ADMIN_SECTIONS, self::TABLE_ADMIN_SETTINGS ];
+		foreach ($tables as $table) {
+			$classes = $this->getClasses($table);
+			foreach($classes as $className) {
+				try {
+					\OC::$server->query($className);
+				} catch (QueryException $e) {
+					$this->remove($table, $className);
+				}
+			}
+		}
+	}
+
+	/**
+	 * returns the registerd classes in the given table
+	 *
+	 * @param $table
+	 * @return string[]
+	 */
+	private function getClasses($table) {
+		$q = $this->dbc->getQueryBuilder();
+		$resultStatement = $q->select('class')
+			->from($table)
+			->execute();
+		$data = $resultStatement->fetchAll();
+		$resultStatement->closeCursor();
+
+		return array_map(function($row) { return $row['class']; }, $data);
+	}
+
 	/**
 	 * @param string $sectionClassName
 	 */

lib/private/Settings/RemoveOrphaned.php

@@ -0,0 +1,91 @@
+<?php
+/**
+ * @copyright Copyright (c) 2016 Arthur Schiwon <blizzz@arthur-schiwon.de>
+ *
+ * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace OC\Settings;
+
+use OC\BackgroundJob\JobList;
+use OC\BackgroundJob\TimedJob;
+use OC\NeedsUpdateException;
+use OCP\BackgroundJob\IJobList;
+use OCP\ILogger;
+
+/**
+ * Class RemoveOrphaned
+ *
+ * @package OC\Settings
+ */
+class RemoveOrphaned extends TimedJob {
+
+	/** @var IJobList */
+	private $jobList;
+
+	/** @var ILogger */
+	private $logger;
+
+	/** @var Manager */
+	private $manager;
+
+	public function __construct(Manager $manager = null) {
+		if($manager !== null) {
+			$this->manager = $manager;
+		} else {
+			// fix DI for Jobs
+			$this->manager = \OC::$server->getSettingsManager();
+		}
+	}
+
+	/**
+	 * run the job, then remove it from the job list
+	 *
+	 * @param JobList $jobList
+	 * @param ILogger $logger
+	 */
+	public function execute($jobList, ILogger $logger = null) {
+		// add an interval of 15 mins
+		$this->setInterval(15*60);
+
+		$this->jobList = $jobList;
+		$this->logger = $logger;
+		parent::execute($jobList, $logger);
+	}
+
+	/**
+	 * @param array $argument
+	 * @throws \Exception
+	 * @throws \OC\NeedsUpdateException
+	 */
+	protected function run($argument) {
+		try {
+			\OC_App::loadApps();
+		} catch (NeedsUpdateException $ex) {
+			// only run when apps are up to date
+			return;
+		}
+
+		$this->manager->checkForOrphanedClassNames();
+
+		// remove the job once executed successfully
+		$this->jobList->remove($this);
+	}
+
+}

lib/private/legacy/app.php

@@ -51,6 +51,7 @@ use OC\App\Platform;
 use OC\Installer;
 use OC\OCSClient;
 use OC\Repair;
+use OCP\App\ManagerEvent;
 
 /**
  * This class manages the apps. It allows them to register and integrate in the
@@ -1237,6 +1238,10 @@ class OC_App {
 		$version = \OC_App::getAppVersion($appId);
 		\OC::$server->getAppConfig()->setValue($appId, 'installed_version', $version);
 
+		\OC::$server->getEventDispatcher()->dispatch(ManagerEvent::EVENT_APP_UPDATE, new ManagerEvent(
+			ManagerEvent::EVENT_APP_UPDATE, $appId
+		));
+
 		return true;
 	}
 

lib/public/App/ManagerEvent.php

@@ -36,6 +36,11 @@ class ManagerEvent extends Event {
 	const EVENT_APP_ENABLE_FOR_GROUPS = 'OCP\App\IAppManager::enableAppForGroups';
 	const EVENT_APP_DISABLE = 'OCP\App\IAppManager::disableApp';
 
+	/**
+	 * @since 9.1.0
+	 */
+	const EVENT_APP_UPDATE = 'OCP\App\IAppManager::updateApp';
+
 	/** @var string */
 	protected $event;
 	/** @var string */

lib/public/Settings/IManager.php

@@ -64,6 +64,21 @@ interface IManager {
 	 */
 	public function onAppDisabled($appId);
 
+	/**
+	 * The method should check all registered classes whether they are still
+	 * instantiable and remove them, if not. This method is called by a
+	 * background job once, after one or more apps were updated.
+	 *
+	 * An app`s info.xml can change during an update and make it unknown whether
+	 * a registered class name was changed or not. An old one would just stay
+	 * registered. Another case is if an admin takes a radical approach and
+	 * simply removes an app from the app folder. These unregular checks will
+	 * take care of such situations.
+	 *
+	 * @since 9.1.0
+	 */
+	public function checkForOrphanedClassNames();
+
 	/**
 	 * returns a list of the admin sections
 	 *