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From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Davide Berardi <davide.berardi6@unibo.it>,
	"git@vger.kernel.org" <git@vger.kernel.org>
Subject: Re: [PATCH v2] clone: Don't segfault on -b specifing a non-commit
Date: Tue, 5 Nov 2019 23:05:23 -0500	[thread overview]
Message-ID: <20191106040523.GB4307@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqbltpyeel.fsf@gitster-ct.c.googlers.com>

On Wed, Nov 06, 2019 at 10:36:18AM +0900, Junio C Hamano wrote:

> >   - we could probably simplify this by just inlining it into
> >     update_head(). Something like:
> >
> >       if (our)
> >               tip = &our->old_oid;
> >       else if (remote)
> >               tip = &remote->old_oid;
> >
> >       if (!tip) {
> > 	      /*
> > 	       * We have no local branch requested with "-b", and the
> > 	       * remote HEAD is unborn. There's nothing to update HEAD
> > 	       * to, but this state is not an error.
> > 	       */
> >               return 0;
> >       }
> 
> I somehow had an impression that Davide was protecting against the
> case where tip->old_oid is null_oid (cloning from an empty repo?);
> NULL return from lookup_commit_reference_gently(null_oid) would not
> deserve a warning from this codepath, and should work just like the
> way it has worked before these changes.

I'm not sure if we need to worry about that case. Right now it would
just segfault, I think, which means it's not something that comes up
regularly (though whether the _best_ thing might be to consider a
non-error, I don't know without understanding why we'd see a null_oid in
the first place).

If we did want to handle it, though, I think it would be easy with the
setup I described; update_head() could check is_null_oid() itself.

-Peff

  reply	other threads:[~2019-11-06  4:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01  0:24 [PATCH] Segmentation Fault on non-commit --branch clone Davide Berardi
2019-11-01 19:08 ` Johannes Schindelin
2019-11-01 19:35   ` Jeff King
2019-11-02 10:16     ` Junio C Hamano
2019-11-03 18:16       ` Davide Berardi
2019-11-04  3:55         ` Junio C Hamano
2019-11-02  9:18   ` Junio C Hamano
2019-11-01 19:43 ` Jeff King
2019-11-02 10:07 ` Junio C Hamano
2019-11-03 18:07 ` [PATCH v2] clone: Don't segfault on -b specifing a non-commit Davide Berardi
2019-11-05  4:37   ` Jeff King
2019-11-06  1:36     ` Junio C Hamano
2019-11-06  4:05       ` Jeff King [this message]
2019-11-06  9:53         ` Junio C Hamano

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