public function getRelative($root) {
        if ($root instanceof FileObject) {
            $root = $root->getFullName();
        } else {
            $root = rtrim($this->getSafePath($root), '/');
        }
        if (strpos($this->fullName, $root) === 0) {
            return substr($this->fullName, strlen($root));
        }
        return false;
    }