Give storages the option to implement the getById behaviour for View->getPath

lib/private/files/cache/cache.php

@@ -593,6 +593,22 @@ class Cache {
 		}
 	}
 
+	/**
+	 * get the storage id of the storage for a file and the internal path of the file
+	 *
+	 * @param int $id
+	 * @return string | null
+	 */
+	public function getPathById($id) {
+		$sql = 'SELECT `path` FROM `*PREFIX*filecache` WHERE `fileid` = ? AND `storage` = ?';
+		$result = \OC_DB::executeAudited($sql, array($id, $this->getNumericStorageId()));
+		if ($row = $result->fetchRow()) {
+			return $row['path'];
+		} else {
+			return null;
+		}
+	}
+
 	/**
 	 * get the storage id of the storage for a file and the internal path of the file
 	 *

lib/private/files/view.php

@@ -1129,15 +1129,22 @@ class View {
 	 * @return string
 	 */
 	public function getPath($id) {
-		list($storage, $internalPath) = Cache\Cache::getById($id);
-		$mounts = Filesystem::getMountByStorageId($storage);
+		$manager = Filesystem::getMountManager();
+		$mounts = $manager->findIn($this->fakeRoot);
+		$mounts[] = $manager->find($this->fakeRoot);
+		// reverse the array so we start with the storage this view is in
+		// which is the most likely to contain the file we're looking for
+		$mounts = array_reverse($mounts);
 		foreach ($mounts as $mount) {
 			/**
-			 * @var \OC\Files\Mount $mount
+			 * @var \OC\Files\Mount\Mount $mount
 			 */
-			$fullPath = $mount->getMountPoint() . $internalPath;
-			if (!is_null($path = $this->getRelativePath($fullPath))) {
-				return $path;
+			$cache = $mount->getStorage()->getCache();
+			if ($internalPath = $cache->getPathById($id)) {
+				$fullPath = $mount->getMountPoint() . $internalPath;
+				if (!is_null($path = $this->getRelativePath($fullPath))) {
+					return $path;
+				}
 			}
 		}
 		return null;