Tool to manage svn, git or cvs

Question

Is there any tool that allows me to do the following in at least one of these version control tools (svn, cvs or git)? Let's imagine I've a team which is working on a repository. This repository has a lot of files. Is it possible to an administrator of the system to allow some users just to read (check out) a file and allow another one to change it (do the commit)?

If theres no tool for this, would it be interesting to develop it?

Thanks

Answer 1

While for SVN|Git|<some SCM> all possible ACLs work on directory level (not deeper), in both these systems are (and can be used) hooks, in which you can implement any needed commit-policy