protected function _fopen($file, $mode = self::FILE_MODE_BINARY, $use_include_path = false, $context = null)
    {
        if ($this->isVirtual) {
            $file = $this->_prepareForVfs($file);
        }

        $context = (!$context) ? stream_context_get_default() : $context;

        return fopen($file, $mode, $use_include_path, $context);
    }