Unknown software revision

Hello,

I am not sure what I am asking, so I thought I would start here. If I knew the name of this operation, I would look for it. :)

I have also posted to the git-users google group, but signs there tell me this is the better place.

I have a software deployment that was copied out of a git repository but without the .git directories. Thus, I have no idea what revision this deployment is, so I don't know how to upgrade from git. Is there a method, or script out there that can help me?

The trouble is, I should have made a branch or tag when I deployed it to at least freeze that version. At the very least so I can rebase and re- deploy it again. (I could be wrong about this last statement: I am definitely new to git)

I appreciate any assistance you all can give me...

--jason

On Thu, Feb 10, 2011 at 02:33:47PM -0800, Jason Brooks wrote:

Does your set of files match what was in the git tree _exactly_? Or might there be minor changes, new files, etc?

If it should match exactly, you can figure out what tree git would have made out of this content:

  git init
  git add .
  git commit -m foo
  tree=`git rev-parse HEAD^{tree}`

And now you can search in the actual git repository for that tree:

  $ git log --pretty=raw -z | perl -0lne 'print $_, "\n" if /^tree '$tree'$/m'

But obviously that is all based on the hashes of the content, so if even a single byte is missing, added, or different in your deployed copy, you won't find a match.

In that case, your best bet is probably to script a bunch of diffs and see which commit ends up closest. I would do something like:

  1. From the deployed version, prepare your best guess about what the
     git directory would have looked like. Put it in a directory
     "deployed".

  2. Now make a git commit from the deployed state:

       cd deployed
       git init
       git add .
       git commit -m 'deployed version'

  3. In the original git repo, fetch the deployed version in so you
     can diff against it.

       cd /path/to/real/git/repo
       git fetch /path/to/deployed master:deployed

  4. Now you can try diffing "deployed" against every commit in the real
     repo and see what comes closest. Here I'll just count up changed
     lines to assign a score to each commit and show the one with the
     fewest changes:

       git rev-list HEAD | while read commit; do
         git diff-tree --numstat $commit deployed |
         perl -ane '$total += $F[0] + $F[1];
                    END { print $total }'
         echo " $commit"
       done | sort -n

The top of the resulting list is the closest commit. Check it out with "git show" to see if it makes sense.

Hope that helps.

-Peff