function setup(&$installer, $pkg, $atts, $file)
    {
        $this->installer = &$installer;
        $reg = &$this->installer->config->getRegistry();
        $package = $reg->getPackage($pkg->getPackage(), $pkg->getChannel());
        if ($package) {
            $filelist = $package->getFilelist();
            if (isset($filelist[$file]) && isset($filelist[$file]['md5sum'])) {
                $this->md5 = $filelist[$file]['md5sum'];
            }
        }
    }