The problem is, that the HTTP_REFERER
is a full URL and not a file path. So you have to convert it to a path and strip some problematic characters. Something like this should do the trick:
// convert HTTP_REFERER from a URL to a path
$referer = str_replace('http://'.$_SERVER['HTTP_HOST'].'/', '', $_SERVER['HTTP_REFERER']);
// replace all unwanted characters with underscores
$referer_folder = preg_replace('/[^\w\/]+/', '_', $referer);
// set the absolute dir path
$dir = __DIR__ . '/' . $referer_folder . '/gallery/';
if( !is_dir($dir) ) {
mkdir($dir, 0750, true );
}