Re: [PATCH 0/2] fix "rebase -i --root" corrupting root commit

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jul 30, 2018, 15:49 UTC
Message-ID: <nycvar.QRO.7.76.6.1807301747330.10478@tvgsbejvaqbjf.bet>
In-Reply-To: <1f172fc1-4b51-cdf7-e841-5ca41e209be4@talktalk.net>

Hi Phillip,

On Mon, 30 Jul 2018, Phillip Wood wrote:

Show 34 quoted lines

> On 30/07/18 10:29, Eric Sunshine wrote:
> > This series fixes bugs causing corruption of the root commit when
> > "rebase -i --root" is used to swap in a new root commit. In particular,
> > the "author" header has trailing garbage. Some tools handle the
> > corruption somewhat gracefully by showing a bogus date, but others barf
> > on it (gitk, for instance). git-fsck correctly identifies the
> > corruption. I discovered this after git-rebase corrupted one of my own
> > projects.
> > 
> > Unfortunately, these bugs (from js/sequencer-and-root-commits) made it
> > into the v2.18.0 release. It's worrying that a released Git can be
> > creating corrupt commits, but fortunately "rebase -i --root" is not
> > likely used often (especially on well-established projects).
> > Nevertheless, it may be 'maint' worthy and applies cleanly there.
> > 
> > It was only after I diagnosed and fixed these bugs that I thought to
> > check 'pu' and discovered that Akinori MUSHA already made a stab[1] at
> > fixing one of the three bugs which this series fixes. Akinori's fix has
> > the somewhat undesirable property that it adds an extra blank line to
> > the end of the script, as Phillip correctly pointed out in review[2].
> > Patch 2/2 of this series has the more "correct" fix, in addition to
> > fixing another bug.
> > 
> > Moreover, patch 2/2 of this series provides a more thorough fix overall
> > than Akinori, so it may make sense to replace his patch with this
> > series, though perhaps keep the test his patch adds to augment the
> > strict test of the "author" header added by this series.
> 
> Johannes and I have some fixups for Akinori's patch on the branch
> fix-t3403-author-script-test at https://github.com/phillipwood/git
> 
> That branch also contains a fix for the bad quoting of names with "'" in
> them. I think it would be good to somehow try and combine this series
> with those patches.

I would like that, too.

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> I'd really like to see a single function to read and another to write
> the author script that is shared by 'git am' and 'git rebase -i', rather
> than the two writers and three readers we have at the moment. I was
> thinking of doing that in the longer term, but given the extra bug
> you've found in read_author_script() maybe we should do that sooner
> rather than later.

You are at least the second person (after Junio) with that wish.

Please note, however, that the purpose of author-script reading/writing is very different in git-am vs rebase -i, or at least it used to be: read_env_script() in sequencer.c very specifically wants to construct an env parameter for use in run_command().

Don't let me stop you from trying to consolidate the two different code paths, though.

Ciao, Dscho

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> 
> > [1]: https://public-inbox.org/git/86a7qwpt9g.knu@iDaemons.org/
> > [2]: https://public-inbox.org/git/f5b56540-d26a-044e-5f46-1d975f889d06@talktalk.net/
> > 
> > Eric Sunshine (2):
> >   sequencer: fix "rebase -i --root" corrupting author header
> >   sequencer: fix "rebase -i --root" corrupting author header timezone
> > 
> >  sequencer.c                   |  9 +++++++--
> >  t/t3404-rebase-interactive.sh | 10 +++++++++-
> >  2 files changed, 16 insertions(+), 3 deletions(-)
> > 
> 
>