add option to wrap existing mounts

lib/files/mount/manager.php

@@ -95,6 +95,13 @@ class Manager {
 		return $result;
 	}
 
+	/**
+	 * @return Mount[]
+	 */
+	public function getAll() {
+		return $this->mounts;
+	}
+
 	/**
 	 * Find mounts by numeric storage id
 	 *

lib/files/mount/mount.php

@@ -138,4 +138,11 @@ class Mount {
 		}
 		return $path;
 	}
+
+	/**
+	 * @param callable $wrapper
+	 */
+	public function wrapStorage($wrapper) {
+		$this->storage = $wrapper($this->mountPoint, $this->storage);
+	}
 }