class Tar

class Tar implements ArchiverInterface {

  /**
   * The underlying ArchiveTar instance that does the heavy lifting.
   *
   * @var Drupal\Component\Archiver\ArchiveTar
   */
  protected $tar;

  /**
   * Constructs a Tar object.
   *
   * @param string $file_path
   *   The full system path of the archive to manipulate. Only local files
   *   are supported. If the file does not yet exist, it will be created if
   *   appropriate.
   *
   * @throws Drupal\Component\Archiver\ArchiverException
   */
  public function __construct($file_path) {
    $this->tar = new ArchiveTar($file_path);
  }

  /**
   * Implements Drupal\Component\Archiver\ArchiveInterface::add().
   */
  public function add($file_path) {
    $this->tar
      ->add($file_path);
    return $this;
  }

  /**
   * Implements Drupal\Component\Archiver\ArchiveInterface::remove().
   */
  public function remove($file_path) {

    // @todo Archive_Tar doesn't have a remove operation
    // so we'll have to simulate it somehow, probably by
    // creating a new archive with everything but the removed
    // file.
    return $this;
  }

  /**
   * Implements Drupal\Component\Archiver\ArchiveInterface::extract().
   */
  public function extract($path, array $files = array()) {
    if ($files) {
      $this->tar
        ->extractList($files, $path);
    }
    else {
      $this->tar
        ->extract($path);
    }
    return $this;
  }

  /**
   * Implements Drupal\Component\Archiver\ArchiveInterface::listContents().
   */
  public function listContents() {
    $files = array();
    foreach ($this->tar
      ->listContent() as $file_data) {
      $files[] = $file_data['filename'];
    }
    return $files;
  }

  /**
   * Retrieves the tar engine itself.
   *
   * In some cases it may be necessary to directly access the underlying
   * Archive_Tar object for implementation-specific logic. This is for advanced
   * use only as it is not shared by other implementations of ArchiveInterface.
   *
   * @return Archive_Tar
   *   The Archive_Tar object used by this object.
   */
  public function getArchive() {
    return $this->tar;
  }

}