PHP GZ压缩与解压

/*将字符串添加至GZ文件*/
function gz_str($str,$gz_name){
    $fp = gzopen ($gz_name, 'w9');
    gzwrite ($fp, $str);
    gzclose($fp);
}
/*将文件添加至GZ文件*/
function gz_file($file,$gz_name){
    $fp = gzopen ($gz_name, 'w9');
    gzwrite ($fp, file_get_contents($file));
    gzclose($fp);
}
/*读取GZ文件*/
function read_gz($gz_file){
    $buffer_size = 4096; // read 4kb at a time
    $file = gzopen($gz_file, 'rb');
    $str='';
    while(!gzeof($file)) {
        $str.=gzread($file, $buffer_size);
    }
    gzclose($file);
    return $str;
}
/*解压GZ文件*/
function unzip_gz($gz_file){
    $buffer_size = 4096; // read 4kb at a time
    $out_file_name = str_replace('.gz', '', $gz_file);
    $file = gzopen($gz_file, 'rb');
    $out_file = fopen($out_file_name, 'wb');
    $str='';
    while(!gzeof($file)) {
        fwrite($out_file, gzread($file, $buffer_size));
    }
    fclose($out_file);
    gzclose($file);
}