attempt to remove section and settings entries when an app got disabled

lib/base.php

@@ -723,6 +723,7 @@ class OC {
 		self::registerLogRotate();
 		self::registerEncryptionWrapper();
 		self::registerEncryptionHooks();
+		self::registerSettingsHooks();
 
 		//make sure temporary files are cleaned up
 		$tmpManager = \OC::$server->getTempManager();
@@ -801,6 +802,14 @@ class OC {
 		}
 	}
 
+	public static function registerSettingsHooks() {
+		$dispatcher = \OC::$server->getEventDispatcher();
+		$dispatcher->addListener(OCP\App\ManagerEvent::EVENT_APP_DISABLE, function($event) {
+			/** @var \OCP\App\ManagerEvent $event */
+			\OC::$server->getSettingsManager()->onAppDisabled($event->getAppID());
+		});
+	}
+
 	private static function registerEncryptionWrapper() {
 		$manager = self::$server->getEncryptionManager();
 		\OCP\Util::connectHook('OC_Filesystem', 'preSetup', $manager, 'setupStorage');

lib/private/Settings/Manager.php

@@ -93,6 +93,25 @@ class Manager implements IManager {
 		}
 	}
 
+	/**
+	 * attempts to remove an apps section and/or settings entry. A listener is
+	 * added centrally making sure that this method is called ones an app was
+	 * disabled.
+	 *
+	 * @param string $appId
+	 * @since 9.1.0
+	 */
+	public function onAppDisabled($appId) {
+		$appInfo = \OC_App::getAppInfo($appId); // hello static legacy
+
+		if(isset($appInfo['settings'][IManager::KEY_ADMIN_SECTION])) {
+			$this->remove(self::TABLE_ADMIN_SECTIONS, $appInfo['settings'][IManager::KEY_ADMIN_SECTION]);
+		}
+		if(isset($settings['settings'][IManager::KEY_ADMIN_SETTINGS])) {
+			$this->remove(self::TABLE_ADMIN_SETTINGS, $appInfo['settings'][IManager::KEY_ADMIN_SETTINGS]);
+		}
+	}
+
 	/**
 	 * @param string $sectionClassName
 	 */
@@ -222,6 +241,20 @@ class Manager implements IManager {
 		return (bool) $row;
 	}
 
+	/**
+	 * deletes an settings or admin entry from the given table
+	 *
+	 * @param $table
+	 * @param $className
+	 */
+	private function remove($table, $className) {
+		$query = $this->dbc->getQueryBuilder();
+		$query->delete($table)
+			->where($query->expr()->eq('class', $query->createNamedParameter($className)));
+
+		$query->execute();
+	}
+
 	private function setupAdminSettings($settingsClassName) {
 		if(!class_exists($settingsClassName)) {
 			$this->log->debug('Could not find admin section class ' . $settingsClassName);

lib/public/Settings/IManager.php

@@ -50,6 +50,20 @@ interface IManager {
 	 */
 	public function setupSettings(array $settings);
 
+	/**
+	 * attempts to remove an apps section and/or settings entry. A listener is
+	 * added centrally making sure that this method is called ones an app was
+	 * disabled.
+	 *
+	 * What this does not help with is when applications change their settings
+	 * or section classes during their life time. New entries will be added,
+	 * but inactive ones will still reside in the database.
+	 *
+	 * @param string $appId
+	 * @since 9.1.0
+	 */
+	public function onAppDisabled($appId);
+
 	/**
 	 * returns a list of the admin sections
 	 *