Go back in history to an undamaged version?
corruption, git, recovery
Solution
If you remove the corrupted object manually, git will generally let you get at everything else. I deliberately corrupted a git blob (just forced a few bad bytes in the front) and got the following:
$ git fsck
fatal: object bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad is corrupted
$ git gc
Counting objects: 23, done.
error: unable to unpack bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad header
error: inflateEnd: failed
Delta compression using up to 2 threads.
Compressing objects: 100% (12/12), done.
fatal: object bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad is corrupted
error: failed to run repack
$ git fsck --full
fatal: object bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad is corrupted
$ rm -f .git/objects/bd/1b260b0ef92d1a219e1183953fa1ac7cdb4cad
$ git fsck --full
broken link from tree a3070cb66fd169e1443867a8bb137a44103c9f24
to blob bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad
missing blob bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad
$ git cat-file -p 2418b6ba8fd0289933c9351260a272b8e410867f
tree a3070cb66fd169e1443867a8bb137a44103c9f24
parent 8d945134b0cead535d66af29c8eb4228b5dc3763
author [redacted] 1333789753 -0600
committer [redacted] 1333789753 -0600
test corrupted object
$ git checkout 2418b6ba8fd0289933c9351260a272b8e410867f
error: git checkout-index: unable to read sha1 file of morefile (bd1b260b0ef92d1a219e1183953fa1ac7cdb4cad)
D morefile
Note: checking out '2418b6ba8fd0289933c9351260a272b8e410867f'.
You are in 'detached HEAD' state. ...
Note, somewhere along the way it re-pointed the branch `master` to a previous "good" commit (not the immediately-previous one, and I have no idea why) so you may then have to repair your commit history, etc. But everything was there, except for the missing file "morefile" whose blob I corrupted. (I restored it from a backup copy I made in advance and was even able to get the file back, with `git checkout -- morefile`. You could `mv` the corrupted blob somewhere and see if you can recover some of your data from it.)
I'd certainly back up the broken git repo first, Just In Case. :-)
Problem
I have a corrupted loose object. I tried checkout, revert, rebase and may be few other things to go to an original commit. In each case I ran `git fsck` and still had the same problem: ``` > git fsck error: corrupt loose object '25a196217ebb6e341909205575f491022eafc4d9' fatal: loose object 25a196217ebb6e341909205575f491022eafc4d9 (stored in .git/objects/25/a196217ebb6e341909205575f491022eafc4d9) is corrupt ``` is there a way to get rid of corrupted objects without simply deleting .git? I don't have another backup so I can't replace the corrupted object. It's a more narrow question that arose from this git "error: corrupt loose object" after moving a directory update (1): ``` > git gc Counting objects: 747, done. Delta compression using up to 8 threads. error: corrupt loose object '25a196217ebb6e341909205575f491022eafc4d9' fatal: loose object 25a196217ebb6e341909205575f491022eafc4d9 (stored in .git/objects/25/a196217ebb6e341909205575f491022eafc4d9) is corrupt error: failed to run repack ``` update (2): this didn't work either Remove file from git repository (history) update (3): cloning didn't work: ``` > git clone ../dynamicsCode_good/ . Cloning into .... done. error: corrupt loose object '25a196217ebb6e341909205575f491022eafc4d9' fatal: loose object 25a196217ebb6e341909205575f491022eafc4d9 (stored in .git/objects/25/a196217ebb6e341909205575f491022eafc4d9) is corrupt ``` the . directory is empty update (4): removing a corrupted object. ``` > git --version git version 1.7.5.4 > rm -f .git/objects/25/a196217ebb6e341909205575f491022eafc4d9 13:42:57 ~/Dropbox/work/dev/dynamicsCode_torek > git fsck --full missing blob 25a196217ebb6e341909205575f491022eafc4d9 dangling tree 64a970c878fef7deeeb4ce2ffc5e6234a72894ad dangling tree 528e6c121fb8e56097462b2ebb9ec4de66388ce2 ``` first (initial) comment. this comment doesn't even have the corrupted file. ``` > git log |tail -5 commit 150ceebafb9c20769386cc7ffba07f6e6565fae6 Author: Kirill ...gmail.com> Date: Tue Sep 27 22:51:15 2011 -0400 state takes input as input checkout: > git checkout -b 150ceebafb9c20769386cc7ffba07f6e6565fae6 Switched to a new branch '150ceebafb9c20769386cc7ffba07f6e6565fae6' > git gc Counting objects: 783, done. error: unable to find 25a196217ebb6e341909205575f491022eafc4d9 Compressing objects: 100% (776/776), done. fatal: unable to read 25a196217ebb6e341909205575f491022eafc4d9 error: failed to run repack > git fsck --full broken link from tree 4668817140320ad2e04aa946d95dec2c3885d97b to blob 25a196217ebb6e341909205575f491022eafc4d9 missing blob 25a196217ebb6e341909205575f491022eafc4d9 dangling tree 64a970c878fef7deeeb4ce2ffc5e6234a72894ad dangling tree 528e6c121fb8e56097462b2ebb9ec4de66388ce2 ``` I also tried unpacking the only object in the `.git/objects/pack/` directory. didn't help. I also cloned this state into a new directory: ``` > git gc Counting objects: 662, done. error: unable to find 25a196217ebb6e341909205575f491022eafc4d9 Compressing objects: 100% (656/656), done. fatal: unable to read 25a196217ebb6e341909205575f491022eafc4d9 error: failed to run repack 14:40:34 ~/Dropbox/work/dev/dynamicsCode_torek_commit_clone > git fsck broken link from tree b5ab6b287804d5069a3c8648ace38d9d9feac1a5 to blob 25a196217ebb6e341909205575f491022eafc4d9 dangling commit dad8edc620248d3911b7b1c0a99608a64e0288a3 missing blob 25a196217ebb6e341909205575f491022eafc4d9 dangling tree 64a970c878fef7deeeb4ce2ffc5e6234a72894ad dangling commit ae2b2a9edb744d9e91aa78891c849d5a0040ea94 dangling commit 32ed79bd4ac70b118d046cb6093a4710562e95ba dangling commit 7e45ef0c6ffc46401b1f82bcbf0f7e843abf9e31 dangling tree 528e6c121fb8e56097462b2ebb9ec4de66388ce2 14:40:40 ~/Dropbox/work/dev/dynamicsCode_torek_commit_clone > git branch * 150ceebafb9c20769386cc7ffba07f6e6565fae6 ``` didn't help either. The corrupted file is `tags` from ctags. I don't need it. it's strange that i can't rebuild git without that file. Most importantly, from all my research I don't see neither how it can be done nor why it's not possible. update (5): checkout without branching ``` > git checkout 150ceebafb9c20769386cc7ffba07f6e6565fae6 Note: checking out '150ceebafb9c20769386cc7ffba07f6e6565fae6'. You are in 'detached HEAD' state. You can look around, make experimental changes and commit them, and you can discard any commits you make in this state without impacting any branches by performing another checkout. If you want to create a new branch to retain commits you create, you may do so (now or later) by using -b with the checkout command again. Example: git checkout -b new_branch_name HEAD is now at 150ceeb... state takes input as input 16:41:40 ~/Dropbox/work/dev/dynamicsCode_torek_commit > git fsck --full broken link from tree 4668817140320ad2e04aa946d95dec2c3885d97b to blob 25a196217ebb6e341909205575f491022eafc4d9 missing blob 25a196217ebb6e341909205575f491022eafc4d9 dangling tree 64a970c878fef7deeeb4ce2ffc5e6234a72894ad dangling tree 528e6c121fb8e56097462b2ebb9ec4de66388ce2 ```