code: public function extract($pathExtracted)
      {
          $file = @gzopen($this->filename, 'r');
  
          if ($file === false) {
              $this->error = "gzopen failed";
              return false;
          }
  
          $output = fopen($pathExtracted, 'w');
          while (!feof($file)) {
              fwrite($output, fread($file, 1024 * 1024));
          }
          fclose($output);
  
          $success = gzclose($file);
          if (false === $success) {
              $this->error = "gzclose failed";
              return false;
          }
  
          return true;
      }
docs: Extracts the contents of the .gz file to $pathExtracted.
  
  @param string $pathExtracted Must be file, not directory.
  @return bool true if successful, false if otherwise.