From: Jeff King <peff@peff.net>
Date: Tue, 08 Aug 2017 22:58:51 GMT
Subject: Re: [PATCH] sha1_file: avoid comparison if no packed hash matches the first byte
Message-ID: <20170808225851.kgbyrlqrtlurzc73@sigill.intra.peff.net>
In-Reply-To: <20170808225231.3l7gyoxxvghsvtv7@sigill.intra.peff.net>

On Tue, Aug 08, 2017 at 06:52:31PM -0400, Jeff King wrote:

> > Interesting.  I see that we still have the conditional code to call
> > out to sha1-lookup.c::sha1_entry_pos().  Do we need a similar change
> > over there, I wonder?  Alternatively, as we have had the experimental
> > sha1-lookup.c::sha1_entry_pos() long enough without anybody using it,
> > perhaps we should write it off as a failed experiment and retire it?
> 
> There is also sha1_pos(), which seems to have the same problem (and is
> used in several places).

Actually, I take it back. The problem happens when we enter the loop
with no entries to look at. But both sha1_pos() and sha1_entry_pos()
return early before hitting their do-while loops in that case.

-Peff