I was trying to find if is possible to configure a custom function to check the uploaded file.
I ended up adding around line 1393 (just before the if(@move_uploaded_file($file['tmp_name'], "$path/$filename")) )
a few lines like
//Callback to perform upload check
if(function_exists("uploadCheck")){
uploadCheck($file);
}
So if the user add in config.php a function to perform certain additional check it will be called.
I think can be an interesting idea to be able to customize not only the JS but also the php in certain point ?