Re: git-reflog bails if branch points to bad commit
On Sep 23, 2010, at 1:35 PM, Ævar Arnfjörð Bjarmason wrote:
Show 18 quoted lines
> On Thu, Sep 23, 2010 at 20:13, Kevin Ballard <kevin@sb.org> wrote:
>
>> Attempting to use `git reflog show foo` or `git log -g foo` will
>> bail with "bad object: foo" if the tip commit of foo is
>> invalid. This seems incredibly non-useful. Why should reflog care if
>> foo points to a valid commit? This bug prevents reflog from being
>> used in a time of great need, which someone just ran into on the
>> #git IRC channel. Their power cut out and they ended up with a
>> corrupt commit on the tip of their branch, and they simply could not
>> view the reflog, which would have enabled them to roll the branch
>> back to a previous commit. Does anybody know why reflog has this
>> behavior?
>
> As you say the repository is probably corrupted, and recovering from
> that may be hard, not much you can do with corrupted data.
>
> Can this person provide a tar-ed copy of the repository so we can look
> at it and be of help, instead of speculating?
The person's problem was eventually resolved by finding another clone of the repository and using it to identify the bad object. However, I was able to trivially reproduce the reflog problem by making a very simple history, then modifying the ref itself to point to a bad hash (I merely incremented the hash by 1). At this point, attempting to say `git reflog show foo` was complaining "fatal: Bad object foo" even though the reflog itself is perfectly valid, and in fact the only problem in the entire repository is the ref currently points to a hash that doesn't exist in the object database.
-Kevin Ballard
Kevin Ballard <kevin@sb.org>