[mod_python] Is it possible to stop file uploading?

> 1.When a user uploads file, using FORM ( POST method), is there a  possibility  to stop 
> uploading, if the file extension  is not among those  allowed? 

Yes. Write out an error and close the HTTP connection.

> 2.
> Is there a good/recommended way how to find out the file extension?
> I use a handler that can find the extension( using  util.FieldStorage(req))
> but it does not stop uploading in progress but uploads the whole file first.

Create a FieldStorage instance, and pass it the callbacks for file 
processing. You'll be called while the file stream is being read, and 
you can check the extension at that time.

Mike.