protected function getConfigurationInstance() {
    // get config file to modify
    $configFiles = $this->configuration->getConfigurations();
    if (sizeof($configFiles) == 0) {
      return false;
    }

    // create a writable configuration and modify the permission
    $mainConfig = $configFiles[0];
    $config = new InifileConfiguration(dirname($mainConfig).'/');
    $config->addConfiguration(basename($mainConfig));
    return [
      'instance' => $config,
      'file' => $mainConfig
    ];
  }