Re: [PATCH v3] multi-pack-index: fix *.rev cleanups with --object-dir

From: Johannes Berg <johannes@sipsolutions.net>
Date: Aug 24, 2021, 07:59 UTC
Message-ID: <f398645c2c946ea0d7cc6d8f603962dde5f7c4e0.camel@sipsolutions.net>
In-Reply-To: <xmqqeeajpyrc.fsf@gitster.g>

On Mon, 2021-08-23 at 15:44 -0700, Junio C Hamano wrote:

Show 17 quoted lines

> Johannes Berg <johannes@sipsolutions.net> writes:
> 
> > If using --object-dir to point into a repo while the current
> > working dir is outside, such as
> > 
> >   git init /repo
> >   git -C /repo ... # add some objects
> >   cd /non-repo
> >   git multi-pack-index --object-dir /repo/.git/objects/ write
> > 
> > the binary will segfault trying to access the object-dir via
> > the repo it found, but that's not fully initialized. Fix it
> 
> OK, so write_midx_internal() was given an object_dir to work in,
> made various changes to that directory, but at the very end of the
> sequence, instead of clearing the revindex in the object_dir we have
> been working in, cleared the odb associated with the repository.

I'm not sure I'd claim "cleared the odb" but it's also not entirely clear to me what you mean by that.

Specifically, what happened is that it cleared out all the .rev files in the objects/pack folder associated with the repository. And if there wasn't actually a repository, it would NULL-ptr-deref instead.

Feel free to rewrite the commit log, or I can if you really want me to. I was more concerned with the segfault, but I can also understand that you'd be more concerned with the on-disk correctness issue this causes.

johannes