I just experienced this - my machine crashed whilst writing to the Git repo, and it became corrupted. I fixed it as follows.
I started with looking at how many commits I had not pushed to the remote repo, thus:
gitk &
If you don't use this tool it is very handy - available on all operating systems as far as I know. This indicated that my remote was missing two commits. I therefore clicked on the label indicating the latest remote commit (usually this will be /remotes/origin/master
) to get the hash (the hash is 40 chars long, but for brevity I am using 10 here - this usually works anyway).
Here it is:
14c0fcc9b3
I then click on the following commit (i.e. the first one that the remote does not have) and get the hash there:
04d44c3298
I then use both of these to make a patch for this commit:
git diff 14c0fcc9b3 04d44c3298 > 1.patch
I then did likewise with the other missing commit, i.e. I used the hash of the commit before and the hash of the commit itself:
git diff 04d44c3298 fc1d4b0df7 > 2.patch
I then moved to a new directory, cloned the repo from the remote:
git clone [email protected]:username/repo.git
I then moved the patch files into the new folder, and applied them and committed them with their exact commit messages (these can be pasted from git log
or the gitk
window):
patch -p1 < 1.patch
git commit
patch -p1 < 2.patch
git commit
This restored things for me (and note there's probably a faster way to do it for a large number of commits). However I was keen to see if the tree in the corrupted repo can be repaired, and the answer is it can. With a repaired repo available as above, run this command in the broken folder:
git fsck
You will get something like this:
error: object file .git/objects/ca/539ed815fefdbbbfae6e8d0c0b3dbbe093390d is empty
error: unable to find ca539ed815fefdbbbfae6e8d0c0b3dbbe093390d
error: sha1 mismatch ca539ed815fefdbbbfae6e8d0c0b3dbbe093390d
To do the repair, I would do this in the broken folder:
rm .git/objects/ca/539ed815fefdbbbfae6e8d0c0b3dbbe093390d
cp ../good-repo/.git/objects/ca/539ed815fefdbbbfae6e8d0c0b3dbbe093390d .git/objects/ca/539ed815fefdbbbfae6e8d0c0b3dbbe093390d
i.e. remove the corrupted file and replace it with a good one. You may have to do this several times. Finally there will be a point where you can run fsck
without errors. You will probably have "dangling commit" and "dangling blob" lines in the report, these are a consequence of your rebases and amends in this folder, and are OK. The garbage collector will remove them in due course.
Thus (at least in my case) a corrupted tree does not mean unpushed commits are lost.
git cat-file -t <SHA1>
will tell you the type. If not corrupted, you can then dogit cat-file <type> <SHA1>
to see the content (I used it for ablob
, I guess it will also show you the contents of other types.) – Cand