Re: My git repo is broken, how to fix it ?

From: Nicolas Pitre <nico@cam.org>
Date: Mar 20, 2007, 15:23 UTC
Message-ID: <alpine.LFD.0.83.0703201113180.18328@xanadu.home>
In-Reply-To: <7vd5349x97.fsf@assigned-by-dhcp.cox.net>

On Tue, 20 Mar 2007, Junio C Hamano wrote:

Show 12 quoted lines

> Linus Torvalds <torvalds@linux-foundation.org> writes:
> 
> > But to really look at this we should probably add a "really_careful" flag 
> > that actually re-verifies the SHA1 on read so that we'd catch these kinds 
> > of corruptions early. 
> > ...
> > I'm hoping somebody has any ideas. We really *could* check the SHA1 on 
> > each read (and slow down git a lot) and that would catch corruption much 
> > faster and hopefully pinpoint it more quickly where exactly it happens. 
> 
> At least, we could do something like this to catch the breakage
> when we (re)pack, to prevent damage from propagating.

I think it would be better to retest the SHA1 when we're about to _write_ the object out to the pack, replacing check_pack_inflate() and revalidate_loose_object() with the full SHA1 check, and testing objects which data isn't reused from a pack too. And make it conditional on !pack_to_stdout like we already do of course.

Nicolas