Re: propagating repo corruption across clone

From: Jeff King <peff@peff.net>
Date: Mar 24, 2013, 19:23 UTC
Message-ID: <20130324192350.GA20688@sigill.intra.peff.net>
In-Reply-To: <CACBZZX6czzJRF9TEsc8c+=LND6SxaVvrZdbcZ+TfUZTWQOpW0Q@mail.gmail.com>

On Sun, Mar 24, 2013 at 08:01:33PM +0100, Ævar Arnfjörð Bjarmason wrote:

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> On Sun, Mar 24, 2013 at 7:31 PM, Jeff King <peff@peff.net> wrote:
> >
> > I don't have details on the KDE corruption, or why it wasn't detected
> > (if it was one of the cases I mentioned above, or a more subtle issue).
> 
> One thing worth mentioning is this part of the article:
> 
> "Originally, mirrored clones were in fact not used, but non-mirrored
> clones on the anongits come with their own set of issues, and are more
> prone to getting stopped up by legitimate, authenticated force pushes,
> ref deletions, and so on – and if we set the refspec such that those
> are allowed through silently, we don’t gain much. "
> 
> So the only reason they were even using --mirror was because they were
> running into those problems with fetching.

I think the --mirror thing is a red herring. It should not be changing the transport used, and that is the part of git that is expected to catch such corruption.

But I haven't seen exactly what the corruption is, nor exactly what commands they used to clone. I've invited the blog author to give more details in this thread.

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> So aside from the problems with --mirror I think we should have
> something that updates your local refs to be exactly like they are on
> the other end, i.e. deletes some, non-fast-forwards others etc.
> (obviously behind several --force options and so on). But such an
> option *wouldn't* accept corrupted objects.

That _should_ be how "git fetch --prune +refs/*:refs/*" behaves (and that refspec is set up when you use "--mirror"; we should probably have it turn on --prune, too, but I do not think you can do so via a config option currently).

-Peff