class Tar

class Tar implements ArchiverInterface {
    
    /**
     * The underlying ArchiveTar instance that does the heavy lifting.
     *
     * @var \Drupal\Core\Archiver\ArchiveTar
     */
    protected $tar;
    
    /**
     * Constructs a Tar object.
     *
     * @param string $file_path
     *   The full system path of the archive to manipulate. Only local files
     *   are supported. If the file does not yet exist, it will be created if
     *   appropriate.
     *
     * @throws \Drupal\Core\Archiver\ArchiverException
     */
    public function __construct($file_path) {
        $this->tar = new ArchiveTar($file_path);
    }
    
    /**
     * {@inheritdoc}
     */
    public function add($file_path) {
        $this->tar
            ->add($file_path);
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    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;
    }
    
    /**
     * {@inheritdoc}
     */
    public function extract($path, array $files = []) {
        if ($files) {
            $this->tar
                ->extractList($files, $path, '', FALSE, FALSE);
        }
        else {
            $this->tar
                ->extract($path, FALSE, FALSE);
        }
        return $this;
    }
    
    /**
     * {@inheritdoc}
     */
    public function listContents() {
        $files = [];
        foreach ($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;
    }

}