lbry.com/lib/tools/Gzip.class.php

<?php

class Gzip
{
  public static function compressFile($source, $level = 1)
  {
    $compressedPath  = $source . '.gz';
    $mode  = 'wb' . $level;

    $fpOut = gzopen($compressedPath, $mode);
    if (!$fpOut)
    {
      return false;
    }

    $fpIn = fopen($source, 'rb');
    $error = false;
    if ($fpIn)
    {
      while (!feof($fpIn))
      {
        gzwrite($fpOut, fread($fpIn, 1024 * 512));
      }
      fclose($fpIn);
    }
    else
    {
      $error = true;
    }

    gzclose($fpOut);

    return $error ? false : $compressedPath;
  }
}