private function base64_to_file($data, $target)
{
touch($target);
if (is_writable($target) == false) {
exit("{$target} is not writable");
}
$whandle = fopen($target, 'wb');
stream_filter_append($whandle, 'convert.base64-decode', STREAM_FILTER_WRITE);
fwrite($whandle, $data);
fclose($whandle);
}