Re: email as a bona fide git transport

From: Vegard Nossum <vegard.nossum@oracle.com>
Date: Oct 18, 2019, 16:50 UTC
Message-ID: <de49fe5e-85cb-9fb0-f9f4-c294d72e356c@oracle.com>
In-Reply-To: <20191018161547.GG21137@mit.edu>

On 10/18/19 6:15 PM, Theodore Y. Ts'o wrote:

Show 14 quoted lines

> On Fri, Oct 18, 2019 at 04:27:48PM +0200, Vegard Nossum wrote:
>> commit ac30b08065cd55362a7244a3bbc8df3563cefaaa
>> tree 8f09d9d6ed78f8617b2fe54fe9712990ba808546
>> parent 108b97dc372828f0e72e56bbb40cae8e1e83ece6
>> author Vegard Nossum <vegard.nossum@oracle.com> 1570284959 +0200
>> committer Vegard Nossum <vegard.nossum@oracle.com> 1571408340 +0200
>> gpgsig -----BEGIN PGP SIGNATURE-----
> 	...
> 
> Would it perhaps be possible to put some or all of these headers after
> the patch, as a set of "trailers"?  That would make it easier for
> human readers of the e-mail to get the bits that they most care
> about.... namely, the patch itself.  :-)
>

Yes, agreed.

I started out using this approach, but I changed it because the implementation was a bit annoying: 'git am' runs 'git mailsplit', which just splits the email into two parts:

1) headers, changelog, and diffstat;
2) diff and signature.

One of my PoC patches changes mailsplit to split the extra metadata into a third file.

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.

I can try to put it at the end, but maybe the git people have some hints that would make the implementation easier? Is it okay to reimplement a simple diff parser in mailsplit?

Thanks,

Vegard