Re: [PATCH 1/1] verify-tag/verify-commit should exit unsuccessfully when signature is not trusted

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Aug 9, 2018, 01:43 UTC
Message-ID: <20180809014302.GB34639@genre.crustytoothpaste.net>
In-Reply-To: <xmqqzhxwcq2o.fsf@gitster-ct.c.googlers.com>

On Wed, Aug 08, 2018 at 05:59:43PM -0700, Junio C Hamano wrote:

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> "brian m. carlson" <sandals@crustytoothpaste.net> writes:
> 
> >> FWIW, I'm on board with returning non-zero in any case where gpg would.
> >
> > I think that's probably the best solution overall.
> 
> FWIW, I am not married to the current behaviour.  I would not be
> surprised if it mostly came by accident and not designed.

Since apparently I was the author of the commit that changed the behavior originally, let me simply say that I was not aware that gpg signalled the correctness of a signature by its exit status when I wrote that patch. If I had known that, I would have deferred to gpg in my change. My goal was consistency between verify-tag and verify-commit, and in retrospect I probably made the wrong decision.

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> > There's a bug report
> > in Debian (https://bugs.debian.org/895048) that requests that behavior
> > instead of the status quo, and also it's the behavior that's documented:
> 
> The last bit is a bit questionable; I think you are reading too much
> into the description.
> 
> A substitute for gpg.program MUST signal good (or not good)
> signature the same way as gpg would with its exit code---that is all
> the description says.  It does not say anything about how that exit
> code affects the exit status of "tag --verify" and friends that
> called gpg.program.

I agree that the description doesn't specifically say that. In fact, it doesn't explicitly say that it must exit nonzero on a bad signature, although I agree with your interpretation that that would be logical (and, AIUI, the behavior of gpg).

However, I would assert that we do want Git's verification to exit successfully on a good signature and unsuccessfully on a bad signature, and deferring to gpg may be the most robust way of ensuring that.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204