Web-based online file editing with revision control built in?

Does anyone know of a simple online file editor that I could put in a folder on the server to enable users to view and modify files? It would have read/write access to source code files (html & css) and open those up in a web-based code editor.

Then when they save it, it would need to have a hook to be able to commit the changes back to whatever revision control system is in place.

Basically I need github.com's capability to edit files that are in a repository wit开发者_StackOverflow中文版hout checking the project out.

PHP would probably be the easiest to be able to just drop into a folder, but whatever works.

The Github wiki is open source: https://github.com/github/gollum - it stores the files in the git repository. I don't know of a pure file editor, though.