process committed files in post-receive hook

Hi guys,

I am writing a post-receive hook in Python that examines the content of some files (the HEAD rev). Because the repo is a bare one on the server. My current approach is to check out a working copy on the server and run 'git pull' in post- receive to get the most up-to-date version, and then process files in the working copy.

I have two questions. First, is there a way that I can access file content in a bare repo without checking out a working copy? If this is not possible, my approach would be reasonable. However, when 'git pull' was called in the python script post-receive when a commit occurs, it gives an error.

remote: fatal: Not a git repository: '.'

The call in python is

subprocess.Popen(["git", "pull"], cwd="/Users/git/ts.git.workingcopy")

I read from a post (http://stackoverflow.com/questions/4043609/) that GIT_DIR is causing this error. Is it safe to unset GIT_DIR in post-receive?

Thanks a lot.