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From: Junio C Hamano <gitster@pobox•com>
To: Jonathan Nieder <jrnieder@gmail•com>
Cc: Jeff King <peff@peff•net>, git@vger•kernel.org
Subject: Re: [PATCHv2] write_index: optionally allow broken null sha1s
Date: Sun, 25 Aug 2013 23:03:54 -0700	[thread overview]
Message-ID: <xmqqob8lj8dx.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20130825195412.GA2752@elie.Belkin> (Jonathan Nieder's message of "Sun, 25 Aug 2013 12:54:12 -0700")

Jonathan Nieder <jrnieder@gmail•com> writes:

> In other words, why not use something like this?
>
> 	write_index: optionally allow broken null sha1s
>
> 	Commit 4337b58 (do not write null sha1s to on-disk index, 2012-07-28)
> 	added a safety check preventing git from writing null sha1s into the
> 	index. The intent was to catch errors in other parts of the code that
> 	might let such an entry slip into the index (or worse, a tree).
>
> 	Some existing repositories have some invalid trees that contain null
> 	sha1s already, though.  Until 4337b58, a common way to clean this up
> 	would be to use git-filter-branch's index-filter to repair such broken
> 	entries.  That now fails when filter-branch tries to write out the
> 	index.
>
> 	Introduce a GIT_ALLOW_NULL_SHA1 environment variable to relax this check
> 	and make it easier to recover from such a history.

I found this version more readable than Peff's (albeit slightly).

> After this patch, do you think (in a separate change) it would make
> sense for cache-tree.c::update_one() to check for null sha1 and error
> out unless GIT_ALLOW_NULL_SHA1 is true?  That would let us get rid of
> the caveat from the last paragraph.

Hmm, interesting thought.

  reply	other threads:[~2013-08-26  6:04 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-08-24  1:33 [PATCH] write_index: optionally allow broken null sha1s Jeff King
2013-08-25  6:15 ` Jonathan Nieder
2013-08-25  9:58   ` [PATCHv2] " Jeff King
2013-08-25 19:54     ` Jonathan Nieder
2013-08-26  6:03       ` Junio C Hamano [this message]
2013-08-26 14:31         ` Jeff King
2013-08-26 16:02           ` Junio C Hamano
2013-08-26 21:36             ` Jeff King
2013-08-26 14:27       ` Jeff King
2013-08-26 17:35         ` Jonathan Nieder
2013-08-26 21:20           ` Jeff King
2013-08-27  3:46             ` Junio C Hamano
2013-08-27 20:41             ` [PATCHv3] " Jeff King

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