protected function readCentralDir()
    {
        $size = filesize($this->file);
        if ($size < 277) {
            $maximum_size = $size;
        } else {
            $maximum_size = 277;
        }

        @fseek($this->fh, $size - $maximum_size);
        $pos   = ftell($this->fh);
        $bytes = 0x00000000;

        while ($pos < $size) {
            $byte  = @fread($this->fh, 1);
            $bytes = (($bytes << 8) & 0xFFFFFFFF) | ord($byte);
            if ($bytes == 0x504b0506) {
                break;
            }
            $pos++;
        }

        $data = unpack(
            'vdisk/vdisk_start/vdisk_entries/ventries/Vsize/Voffset/vcomment_size',
            fread($this->fh, 18)
        );

        if ($data['comment_size'] != 0) {
            $centd['comment'] = fread($this->fh, $data['comment_size']);
        } else {
            $centd['comment'] = '';
        }
        $centd['entries']      = $data['entries'];
        $centd['disk_entries'] = $data['disk_entries'];
        $centd['offset']       = $data['offset'];
        $centd['disk_start']   = $data['disk_start'];
        $centd['size']         = $data['size'];
        $centd['disk']         = $data['disk'];
        return $centd;
    }