function download($file_source, $file_target) {
    $rh = fopen($file_source, 'rb');
    $wh = fopen($file_target, 'wb');
    if ($rh === false || $wh === false) {
        return false;
    }
    while (!feof($rh)) {
        if (fwrite($wh, fread($rh, 1024)) === FALSE) {
            return false;
        }
    }

    fclose($rh);
    fclose($wh);
    return true;
}