Re: heads-up: git-index-pack in "next" is broken

From: Linus Torvalds <torvalds@osdl.org>
Date: Oct 17, 2006, 21:46 UTC
Message-ID: <Pine.LNX.4.64.0610171440080.3962@g5.osdl.org>
In-Reply-To: <Pine.LNX.4.64.0610171706260.1971@xanadu.home>

On Tue, 17 Oct 2006, Nicolas Pitre wrote:

> 
> Because offsets into packs are expressed as unsigned long everywhere 
> else (except in the current pack index on-disk format).

Until your work, that "unsigned long" was totally just an internal thing that didn't actually bleed into anything else.

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> > For some structure like this, it sounds positively wrong. Pack-files 
> > should be architecture-neutral, which means that they shouldn't depend on 
> > word-size, and they should be in some neutral byte-order.
> 
> But they do.  Please consider this code:

Right. The pack-file itself. But the code that actually _generates_ it mixes things in alarming ways.

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> > In contrast, the new union introduced in "next" is just horrid. There's 
> > not even any way to know which member to use, except apparently that it 
> > expects that a SHA1 is never zero in the last 12 bytes. Which is probably 
> > true, but still - that's some ugly stuff.
> 
> This union should be looked at just like a sortable hash pointing to a 
> base object so that deltas with the same base object can be sorted 
> together.

.. and it sorts _differently_ on a big-endian vs little-endian thing, doesn't it?

So now the sort order depends on endianness and/or wordsize. That just sounds really really wrong.

			Linus