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

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

Johannes Berg [off-list ref] writes:

quoted

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