block server-to-server share if files_external is not activates, can be reverted once we moved to the webdav implementation in core

apps/files_sharing/ajax/external.php

@@ -12,7 +12,10 @@ OCP\JSON::checkLoggedIn();
 $l = OC_L10N::get('files_sharing');
 
 // check if server admin allows to mount public links from other servers
-if (OCA\Files_Sharing\Helper::isIncomingServer2serverShareEnabled() === false) {
+// check if files_external is enabled
+// FIXME file_external check no longer needed if we use the webdav implementation from core
+if (OCA\Files_Sharing\Helper::isIncomingServer2serverShareEnabled() === false ||
+		\OC_App::isEnabled('files_external') === false) {
 	\OCP\JSON::error(array('data' => array('message' => $l->t('Server to server sharing is not enabled on this server'))));
 	exit();
 }

apps/files_sharing/lib/external/manager.php

@@ -68,6 +68,12 @@ class Manager {
 	}
 
 	public function setup() {
+		// don't setup server-to-server shares if the file_external app is disabled
+		// FIXME no longer needed if we use the webdav implementation from  core
+		if (\OC_App::isEnabled('files_external') === false) {
+			return false;
+		}
+
 		$user = $this->userSession->getUser();
 		if ($user) {
 			$query = $this->connection->prepare('SELECT `remote`, `share_token`, `password`, `mountpoint`, `owner`