[TYPO3] readfile in extension

[Roberto Torresani]

Hi!

I write a extension where I want read a file and write it to the output.
Now I set the Content-Type and use the php command readfile.

When I call the page with my extension in the browser, I receive the file
with at the end the code html of the template in the page.
How can I send to the browser only the read file and not the rest of the
typo3page?

The last command in my extension is "return
$this->pi_wrapInBaseClass($content)";
If I use, for example, the command "exit", in my browser I receive right
only the file, but for some seconds I can not navigate in other page of my
site.

Thanks!
Roberto