system_archiver_info in drupal-7.x/modules/system/system.module

Implements hook_archiver_info().

class ArchiverZip implements ArchiverInterface {

  /**
   * The underlying ZipArchive instance that does the heavy lifting.
   *
   * @var ZipArchive
   */
  protected $zip;

  public function __construct($file_path) {
    $this->zip = new ZipArchive();
    if ($this->zip->open($file_path) !== TRUE) {
      // @todo: This should be an interface-specific exception some day.
      throw new Exception(t('Cannot open %file_path', array('%file_path' => $file_path)));
    }
  }

  public function add($file_path) {
    $this->zip->addFile($file_path);

    return $this;
  }

  public function remove($file_path) {
    $this->zip->deleteName($file_path);

    return $this;
  }

  public function extract($path, Array $files = array()) {
    if ($files) {
      $this->zip->extractTo($path, $files);
    }
    else {
      $this->zip->extractTo($path);
    }

    return $this;
  }

  public function listContents() {
    $files = array();
    for ($i = 0; $i < $this->zip->numFiles; $i++) {
      $files[] = $this->zip->getNameIndex($i);
    }
    return $files;
  }

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