Getting current page details

I'm using a login routine and I'd like to return the user to the page where they started before going to the login form. I figured I could do this by grabbing the current page details, putting these into a session variable and using that to link back to the page later. So the question is, how do I get the current page's details? I suspect some might say PHP_SELF contained in the $_SERVER array - is this the best way?