A PHP CMS to manage Files and privileges between users

I'm looking for a PHP CMS which can let me to:

1-Uploade and manage files ( pdf, words..) between users by allowing to view, to print or to download.

2-Know who accessed what and when, who downloa开发者_如何学God what and when... who do what and when.

From your requirements I think you might be looking for a DMS (Document Management System) and not a CMS.

In which case, I'd recommend Knowledge Tree:

http://www.knowledgetree.com/