function gzcompressfile($source,$level=false){
    $dest=$source.'.gz';
    $mode='wb'.$level;
    $error=false;
    if($fp_out=gzopen($dest,$mode)){
        if($fp_in=fopen($source,'rb')){
            while(!feof($fp_in))
                gzwrite($fp_out,fread($fp_in,1024*512));
            fclose($fp_in);
            }
          else $error=true;
        gzclose($fp_out);
        }
      else $error=true;
    if($error) return false;
      else return $dest;
    }