protected function readFileHeader($header)
    {
        $binary_data = fread($this->fh, 30);
        $data        = unpack(
            'vchk/vid/vversion/vflag/vcompression/vmtime/vmdate/Vcrc/Vcompressed_size/Vsize/vfilename_len/vextra_len',
            $binary_data
        );

        $header['filename'] = fread($this->fh, $data['filename_len']);
        if ($data['extra_len'] != 0) {
            $header['extra'] = fread($this->fh, $data['extra_len']);
            $header['extradata'] = array_merge($header['extradata'],  $this->parseExtra($header['extra']));
        } else {
            $header['extra'] = '';
            $header['extradata'] = array();
        }

        $header['compression'] = $data['compression'];
        foreach (array(
                     'size',
                     'compressed_size',
                     'crc'
                 ) as $hd) { // On ODT files, these headers are 0. Keep the previous value.
            if ($data[$hd] != 0) {
                $header[$hd] = $data[$hd];
            }
        }
        $header['flag']  = $data['flag'];
        $header['mtime'] = $this->makeUnixTime($data['mdate'], $data['mtime']);

        $header['stored_filename'] = $header['filename'];
        $header['status']          = "ok";
        $header['folder']          = ($header['external'] == 0x41FF0010 || $header['external'] == 16) ? 1 : 0;
        return $header;
    }