Re: [PATCH 1/7] sequencer: clean up pseudo refs with REF_NO_DEREF

From: Patrick Steinhardt <ps@pks.im>
Date: Jan 22, 2024, 12:28 UTC
Message-ID: <Za5fVWZ8oUEpA04F@tanuki>
In-Reply-To: <CAOLa=ZQakWpRgFZdLnALq9f+acAR3hBwgO_kxJ6gb_yv+vrX=g@mail.gmail.com>

On Mon, Jan 22, 2024 at 03:49:37AM -0800, Karthik Nayak wrote:

Show 13 quoted lines

> Patrick Steinhardt <ps@pks.im> writes:
> 
> > When cleaning up the state-tracking pseudorefs CHERRY_PICK_HEAD or
> > REVERT_HEAD we do not set REF_NO_DEREF. In the unlikely case where those
> > refs are a symref we would thus end up deleting the symref targets, and
> > not the symrefs themselves.
> >
> > Harden the code to use REF_NO_DEREF to fix this.
> >
> 
> Just a question for my understanding. Is that that currently
> CHERRY_PICK_HEAD or REVERT_HEAD are never symrefs, so we don't really
> worry about this, but adding this change makes it safer?

They shouldn't ever be, at least Git would never end up writing symrefs there. So for those refs to be symrefs the user would need to manually create them as such, and in that case it would certainly be unexpected if we deleted the symref targets when cleaning up state after a revert or cherry-pick.

So yes, it's about hardening the code for edge cases that shouldn't really happen in the first place.

Patrick