From: Jeff King <peff@peff.net>
Date: Fri, 18 Nov 2011 21:08:25 GMT
Subject: Re: [PATCH] receive-pack, fetch-pack: reject bogus pack that records objects twice
Message-ID: <20111118210825.GA14710@sigill.intra.peff.net>
In-Reply-To: <7v62ihkzhb.fsf@alter.siamese.dyndns.org>

On Fri, Nov 18, 2011 at 11:22:08AM -0800, Junio C Hamano wrote:

> >> > If we are fixing a thin pack (which should be the case most of the
> >> > time), we are rewriting the packfile anyway. Shouldn't we just omit
> >> > the duplicate?
> >> ...
> > ... But I guess there is some complexity
> > with deltified entries? As in, if the first entry is deltified but the
> > second is not, you would want to keep the second one?
> 
> I think you answered your own question here; it is not "some complexity"
> but is exactly the "you need to memmove() in the output file" situation in
> the message you are responding to.
> 
> Upon seeing a delta, you would not know if the same object as this delta
> represents appears later in the pack stream, which means until you read to
> the end you wouldn't know.  You obviously would not want to hold onto all
> deltas in-core to "just omit the duplicate".

OK, that makes sense to me. It's nice to hear it confirmed from somebody
who obviously thought more about it.

-Peff