From: Phillip Wood <phillip.wood123@gmail.com>
Date: Thu, 01 Dec 2022 14:43:14 GMT
Subject: Re: What are cherry-pick's exit codes?
Message-ID: <40ffe56e-cec2-7130-ca4f-2186a1b7681c@dunelm.org.uk>
In-Reply-To: <878rjry5a7.fsf@gmail.com>

Hi Sean

On 01/12/2022 06:39, Sean Allred wrote:
> Hi folks,
> 
> We're developing some internal tooling wrapping git-cherry-pick and need
> to be able to distinguish its different error codes. Problem is: these
> exit codes don't seem to be documented in git-cherry-pick.txt.
> 
> Looking at the source, I found myself down the rabbit-hole very quickly.
> I'm not too familiar with the coding patterns quite yet -- but I'm
> pretty sure I eventually found myself redirected to git-commit in one
> case. At that point, I thought it better to ask here.
> 
> I'd like to document these exit codes in the manpage and I'm more than
> happy to submit the patch, but I thought I'd confirm my understanding
> first since it's based purely on reading the cherry-pick tests:
> 
> Exit code:
> 
>    - 0: success, sequencer complete -- no conflicts

I believe this is correct.

>    - 1: 'success', sequencer incomplete -- conflicts encountered

One can get exit code 1 without conflicts. One example is when it cannot 
cherry-pick a commit because it would overwrite an untracked file. 
Another example is when a picked commit would be empty because the 
changes are already in HEAD.

>    - 127: fatal -- lots of reasons -- I'm guessing this is value for the
>      'return -1' and 'return error(...)' statements speckled throughout
>      the code, but it's been a long time since I cared about two's
>      complement so I may be wrong here.
> 
>    - 128: fatal -- sequence is interrupted, possibly due to some other
>      fatal error, e.g., 'commit doesn't exist' or 'mainline parent number
>      doesn't exist'
> 
>    - 129: fatal -- there was nothing to cherry-pick at all (e.g. empty
>      range)

A high exit code from die() indicates something bad happened but I'm not 
sure one can rely on the exact value to tell you what happened.

Best Wishes

Phillip

> I'm reasonably confident about 0/1 just anecdotally -- I'm less sure
> about everything else.
> 
> Obviously the actual text put in the manpage should be friendlier and
> possibly vaguer for clarity (paradoxical, perhaps, but it seems more
> direct to say '0 for success, 1 for conflicts, and anything else is a
> fatal error'), but I wanted to make sure that I have an actually-
> accurate understanding rather than something only surface-level.
> 
> Two questions:
> 
>    1. Are the exit codes actually documented somewhere already that
>       should simply be linked from git-cherry-pick.txt?
> 
>    2. If not, is the above listing the exit codes accurate and complete?
> 
> Thanks!
> 
> --
> Sean Allred