Re: [RFC/PATCH 1/2] commit: add parse_commit_repl() to replace commits at parsing time

> On Wed, Aug 18, 2010 at 7:18 AM, Junio C Hamano <gitster@pobox.com> wrote:
> > Christian Couder <chriscool@tuxfamily.org> writes:
> >> The function parse_commit() is not safe regarding replaced commits
> >> because it uses the buffer of the replacement commit but the object
> >> part of the commit struct stay the same. Especially the sha1 is not
> >> changed so it doesn't match the content of the commit.
> > 
> > This all sounds backwards to me, if I am reading the discussion
> > correctly.
> > 
> > If a replace record says commit 0123 is replaced by commit 4567 (iow,
> > 0123 was a mistake, and pretend that its content is what is recorded in
> > 4567), and when we are honoring the replace records (iow, we are not
> > fsck), shouldn't read_sha1("0123") give us a piece of memory that stores
> > what is recorded in 4567, parse_object("0123") return a struct commit
> > whose buffer points at a block of memory that has what is recorded in
> > 4567 _while_ its object.sha1[] say "0 123"?
> 
> 1. parse_object() as it is now would return object.sha1[] = "4567".
> 2. lookup_commit(), then parse_commit() would return object.sha1[] =
> "0123".
> 
> > What problem are you trying to solve?
> 
> Inconsistency in replacing objects. I have no comments whether #1 or
> #2 is expected behavior. But at least it should stick to one behavior
> only.