Fixing Git

I use git as my version control system for all of my sites. It helps to reduce disk usage by occasionally running git gc. Last night when I went to run git gc on one of my sites, I received a message I had never seen before telling me that my git repo was corrupt. Corrupt? Oh noes!

So I searched the internet and discovered I could run git fsck –full to figure out what the problem was:

$ git fsck --full
broken link from    tree e79ab5efffca93a784afdb9cef73801eb1fa9db4
              to    tree fb9d707c76dde3f8cb672d1c07ca046615175587
dangling tree 1003e43ee3725b0482193aea9d82ca527c2903cc
dangling blob 361211b552b7910299e63b6627944ff72b0577eb
dangling blob 8e79df8dbe87431fbec8f25a4c6527fabe4d9e6f
dangling blob 9b3a891e5094920f743c36a49d1647d9aad2b2f0
missing tree fb9d707c76dde3f8cb672d1c07ca046615175587

After digging around the internet, I discovered that my repo was missing a tree, and that I could get it out of a cloned copy of the repo, assuming the cloned copy wasn’t corrupt, too.

I created a new empty repo:

$ mkdir new-repo
$ cd new-repo
$ git init

Next, I copied my pack file from the good repo to the new empty repo (there was only one in my pack folder):

$ cd /www/path/to/good/repo
$ cp .git/objects/pack/pack-c376dc3b9d2ce5f4d9ab9269d29ddc82f6f6a822.pack /path/to/new-repo

I unpacked the pack file to see if I could find the missing tree:

$ cd /path/to/new-repo
$ git unpack-objects < pack-c376dc3b9d2ce5f4d9ab9269d29ddc82f6f6a822.pack

My missing tree is fb9d707c76dde3f8cb672d1c07ca046615175587, so I looked to see if my file was there:

$ cd .git/objects/fb/
$ ls -l

9d707c76dde3f8cb672d1c07ca046615175587 showed up in the list, so yay! My missing tree was there! Now to copy it to the corrupt repo (my corrupt repo was a bare repo, so no .git in the path):

$ mkdir -p /path/to/corrupt/repo/objects/fb
$ cp /path/to/new-repo/.git/objects/fb/9d707c76dde3f8cb672d1c07ca046615175587 /path/to/corrupt/repo/objects/fb/9d707c76dde3f8cb672d1c07ca046615175587

That was it for me! I ran git gc and everything worked without a problem.

Hopefully this helps someone, or at least will help me remember what the heck to do next time my repo gets corrupted.

One comment

  1. Very timely, thanks for the post. I was able to unpack the file and find the tree I was missing. I have no idea how it got lost but now it’s found. Sure beats having to setup all my config files in a newly cloned repo. Thanks again.


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