$_files

Hi all!

I have a question: I am constructing a form where the user can upload a file.
I need however to verify that the file uploaded is a TEXT file.

Is $_FILE['userfile']['type'] what I need? I am asking this because no matter if I upload a .txt or a .gif file, PHP says they are both $_FILE['userfile']['type']='text' and so, they are both uploaded on the server, whereas there should be only .txt file uploaded and not the .gif file.

In general, how can I allow only text files to be uploaded?
(Of course, i can't rely much on the extension I believe)..

Thanx