PclZip::privReadEndCentralDir

  function privReadEndCentralDir(&$p_central_dir)
  {
    $v_result=1;

    // ----- Go to the end of the zip file
    $v_size = filesize($this->zipname);
    @fseek($this->zip_fd, $v_size);
    if (@ftell($this->zip_fd) != $v_size)
    {
      // ----- Error log
      PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to go to the end of the archive \''.$this->zipname.'\'');

      // ----- Return
      return PclZip::errorCode();
    }

    // ----- First try : look if this is an archive with no commentaries (most of the time)
    // in this case the end of central dir is at 22 bytes of the file end
    $v_found = 0;
    if ($v_size > 26) {
      @fseek($this->zip_fd, $v_size-22);
      if (($v_pos = @ftell($this->zip_fd)) != ($v_size-22))
      {
        // ----- Error log
        PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to seek back to the middle of the archive \''.$this->zipname.'\'');

        // ----- Return
        return PclZip::errorCode();
      }

      // ----- Read for bytes
      $v_binary_data = @fread($this->zip_fd, 4);
      $v_data = @unpack('Vid', $v_binary_data);

      // ----- Check signature
      if ($v_data['id'] == 0x06054b50) {
        $v_found = 1;
      }

      $v_pos = ftell($this->zip_fd);
    }

    // ----- Go back to the maximum possible size of the Central Dir End Record
    if (!$v_found) {
      $v_maximum_size = 65557; // 0xFFFF + 22;
      if ($v_maximum_size > $v_size)
        $v_maximum_size = $v_size;
      @fseek($this->zip_fd, $v_size-$v_maximum_size);
      if (@ftell($this->zip_fd) != ($v_size-$v_maximum_size))
      {
        // ----- Error log
        PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, 'Unable to seek back to the middle of the archive \''.$this->zipname.'\'');

        // ----- Return
        return PclZip::errorCode();
      }

      // ----- Read byte per byte in order to find the signature
      $v_pos = ftell($this->zip_fd);
      $v_bytes = 0x00000000;
      while ($v_pos < $v_size)
      {
        // ----- Read a byte
        $v_byte = @fread($this->zip_fd, 1);

        // -----  Add the byte
        //$v_bytes = ($v_bytes << 8) | Ord($v_byte);
        // Note we mask the old value down such that once shifted we can never end up with more than a 32bit number
        // Otherwise on systems where we have 64bit integers the check below for the magic number will fail.
        $v_bytes = ( ($v_bytes & 0xFFFFFF) << 8) | Ord($v_byte);

        // ----- Compare the bytes
        if ($v_bytes == 0x504b0506)
        {
          $v_pos++;
          break;
        }

        $v_pos++;
      }

      // ----- Look if not found end of central dir
      if ($v_pos == $v_size)
      {

        // ----- Error log
        PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, "Unable to find End of Central Dir Record signature");

        // ----- Return
        return PclZip::errorCode();
      }
    }

    // ----- Read the first 18 bytes of the header
    $v_binary_data = fread($this->zip_fd, 18);

    // ----- Look for invalid block size
    if (strlen($v_binary_data) != 18)
    {

      // ----- Error log
      PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT, "Invalid End of Central Dir Record size : ".strlen($v_binary_data));

      // ----- Return
      return PclZip::errorCode();
    }

    // ----- Extract the values
    $v_data = unpack('vdisk/vdisk_start/vdisk_entries/ventries/Vsize/Voffset/vcomment_size', $v_binary_data);

    // ----- Check the global size
    if (($v_pos + $v_data['comment_size'] + 18) != $v_size) {

	  // ----- Removed in release 2.2 see readme file
	  // The check of the file size is a little too strict.
	  // Some bugs where found when a zip is encrypted/decrypted with 'crypt'.
	  // While decrypted, zip has training 0 bytes
	  if (0) {
      // ----- Error log
      PclZip::privErrorLog(PCLZIP_ERR_BAD_FORMAT,
	                       'The central dir is not at the end of the archive.'
						   .' Some trailing bytes exists after the archive.');

      // ----- Return
      return PclZip::errorCode();
	  }
    }

    // ----- Get comment
    if ($v_data['comment_size'] != 0) {
      $p_central_dir['comment'] = fread($this->zip_fd, $v_data['comment_size']);
    }
    else
      $p_central_dir['comment'] = '';

    $p_central_dir['entries'] = $v_data['entries'];
    $p_central_dir['disk_entries'] = $v_data['disk_entries'];
    $p_central_dir['offset'] = $v_data['offset'];
    $p_central_dir['size'] = $v_data['size'];
    $p_central_dir['disk'] = $v_data['disk'];
    $p_central_dir['disk_start'] = $v_data['disk_start'];

    // TBC
    //for(reset($p_central_dir); $key = key($p_central_dir); next($p_central_dir)) {
    //}

    // ----- Return
    return $v_result;
  }