Subject: Re: [PATCH] tag: fix sign_buffer() call to create a signed tag

From: Junio C Hamano <[email-masked]>
Date: Wed, 07 Feb 2024 19:08:37 -0800

Jeff King <[email-masked]> writes:

>>  * We alternatively could fix individual sign_buffer() backend that
>>    signals an error with a positive value (sign_buffer_ssh() in this
>>    case) to return a negative value, but this would hopefully be
>>    more future-proof.
>
> FWIW, I would have gone the other way, and fixed sign_buffer_ssh(). Your
> solution here is future-proofing the tag code against other
> sign_buffer_*() functions behaving like ssh. But it is also leaving
> other sign_buffer() callers to introduce the same bug.
>
> Your documentation change at least makes that less likely. But given how
> much of our code uses the "negative is error" convention, I wouldn't be
> surprised to see it happen anyway.

Yeah, but other callers are prepared to honor the current return
value convention used by gpg-interface, so "fixing" sign_buffer_ssh()
would not give us any future-proofing.

We could do belt and suspenders by tightening the other callers to
only expect negative for errors (but then what should they do when
they receive non-zero positive?  Should they BUG() out???) while
teaching sign_buffer_ssh() that our convention is to return negative
for an error, of course, but I am not sure if it that is worth it.

Thanks.