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Subject: Re: email as a bona fide git transport
To:     Willy Tarreau <w@1wt.eu>, "Theodore Y. Ts'o" <tytso@mit.edu>
Cc:     Santiago Torres Arias <santiago@nyu.edu>,
        workflows@vger.kernel.org, Git Mailing List <git@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Konstantin Ryabitsev <konstantin@linuxfoundation.org>,
        Eric Wong <e@80x24.org>
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 <20191018191456.GI21137@mit.edu> <20191020031716.GA17475@1wt.eu>
From:   Vegard Nossum <vegard.nossum@oracle.com>
Message-ID: <1a259d8d-b3d1-b64e-07c3-ba143b42c442@oracle.com>
Date:   Sun, 20 Oct 2019 08:28:31 +0200
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On 10/20/19 5:17 AM, Willy Tarreau wrote:
> On Fri, Oct 18, 2019 at 03:14:56PM -0400, Theodore Y. Ts'o wrote:
>> On Fri, Oct 18, 2019 at 06:50:51PM +0200, Vegard Nossum wrote:
>>> The problem I ran into with putting the metadata at the end was
>>> detecting where the diff ends. A comment in 'git apply' suggested that
>>> detecting the difference between "--" as a diff/signature separator and
>>> as part of the diff is nontrivial in the sense that you need to actually
>>> do some parsing and keep track of hunk sizes.
>>
>> Could we cheat by having "git format-patch" add a "Diff-size" in the
>> header which gives the number of lines in the diff so git am can just
>> count lines to find the Trailer section?
> 
> Be careful with this, it starts like this and ends up with non-editable
> patches. I'd rather have git-am use best-effort detection of the end.

Expect filesystem developers to come up with a format that uses extents ;-)

> Also when dealing with stable backports, I've done a lot of
> "cat foo.diff >> bar.patch" to fixup some patches in which I just had
> to move some parts around. Having to count lines and edit a counter
> somewhere is going to become really painful.

I almost have some new patches ready for putting the metadata after the
patch using a very bare-bones diff parser (it's actually not that bad),
I just need to fix a few corner cases that are causing breakage in the
git test suite.


Vegard