Re: [PATCH] sequencer: honor GIT_REFLOG_ACTION

From: Elijah Newren <newren@gmail.com>
To: Phillip Wood <phillip.wood@dunelm.org.uk>
Cc: Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
	Git Mailing List <git@vger.kernel.org>,
	Jonathan Nieder <jrnieder@gmail.com>,
	Paul Gevers <elbrus@debian.org>,
	Ian Jackson <ijackson@chiark.greenend.org.uk>,
	Alban Gruin <alban.gruin@gmail.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>
Subject: Re: [PATCH] sequencer: honor GIT_REFLOG_ACTION
Date: Thu, 2 Apr 2020 10:01:34 -0700	[thread overview]
Message-ID: <CABPp-BE_mimSRg5wf0Yzn2s-dX=64ZS1jGszqwHzr3aju0bj=A@mail.gmail.com> (raw)
In-Reply-To: <b187cb5f-a6c8-2908-e3fd-e1210e6970e0@gmail.com>

Hi Phillip,

On Thu, Apr 2, 2020 at 2:25 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
>
> Hi Elijah
>
> Thanks for fixing this
>
> On 01/04/2020 21:31, Elijah Newren via GitGitGadget wrote:
> > From: Elijah Newren <newren@gmail.com>
> >
> > There is a lot of code to honor GIT_REFLOG_ACTION throughout git,
> > including some in sequencer.c; unfortunately, reflog_message() and its
> > callers ignored it.  Instruct reflog_message() to check the existing
> > environment variable, and use it when present as an override to
> > action_name().
> >
> > Also restructure pick_commits() to only temporarily modify
> > GIT_REFLOG_ACTION for a short duration and then restore the old value,
> > so that when we do this setting within a loop we do not keep adding "
> > (pick)" substrings and end up with a reflog message of the form
> >      rebase (pick) (pick) (pick) (finish): returning to refs/heads/master
> >
> > Signed-off-by: Elijah Newren <newren@gmail.com>
> > ---
> >      sequencer: honor GIT_REFLOG_ACTION
> >
> >      I'm not the best with getenv/setenv. The xstrdup() wrapping is
> >      apparently necessary on mac and bsd. The xstrdup seems like it leaves us
> >      with a memory leak, but since setenv(3) says to not alter or free it, I
> >      think it's right. Anyone have any alternative suggestions?
> >
> > Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-746%2Fnewren%2Fhonor-reflog-action-in-sequencer-v1
> > Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-746/newren/honor-reflog-action-in-sequencer-v1
> > Pull-Request: https://github.com/git/git/pull/746
> >
> >   sequencer.c               |  9 +++++++--
> >   t/t3406-rebase-message.sh | 16 ++++++++--------
> >   2 files changed, 15 insertions(+), 10 deletions(-)
> >
> > diff --git a/sequencer.c b/sequencer.c
> > index e528225e787..5837fdaabbe 100644
> > --- a/sequencer.c
> > +++ b/sequencer.c
> > @@ -3708,10 +3708,11 @@ static const char *reflog_message(struct replay_opts *opts,
> >   {
> >       va_list ap;
> >       static struct strbuf buf = STRBUF_INIT;
> > +     char *reflog_action = getenv("GIT_REFLOG_ACTION");
>
> Minor nit - you're using a string here rather that the pre-processor
> constant that is used below

Yeah, true.  However, using a mixture of both styles is consistent
with the current code's inconsistency about which one should be used.
:-)

> >       va_start(ap, fmt);
> >       strbuf_reset(&buf);
> > -     strbuf_addstr(&buf, action_name(opts));
> > +     strbuf_addstr(&buf, reflog_action ? reflog_action : action_name(opts));
> >       if (sub_action)
> >               strbuf_addf(&buf, " (%s)", sub_action);
> >       if (fmt) {
> > @@ -3799,8 +3800,10 @@ static int pick_commits(struct repository *r,
> >                       struct replay_opts *opts)
> >   {
> >       int res = 0, reschedule = 0;
> > +     char *prev_reflog_action;
> >
> >       setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
> > +     prev_reflog_action = xstrdup(getenv(GIT_REFLOG_ACTION));
>
> I'm confused as to why saving the environment variable immediately after
> setting it works but the test shows it does - why doesn't this clobber
> the value of GIT_REFLOG_ACTION set by the user?

The third parameter, 0, means only set the environment variable if
it's not already set.