Re: [PATCH] maintenance: compare output of pthread functions for inequality with 0

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Dec 2, 2022, 20:55 UTC
Message-ID: <Y4pl5BzQnw0Fm+5S@tapette.crustytoothpaste.net>
In-Reply-To: <221202.86k039fz7x.gmgdl@evledraar.gmail.com>

On 2022-12-02 at 18:10:57, Ævar Arnfjörð Bjarmason wrote:

Show 12 quoted lines

> 
> But (and especially if you're interested) we really should follow-up
> here and fix the "error()" etc. part of this. After this we have cases
> in-tree where we on failure:
> 
>  * Call die_errno() (good)
>  * Call die(), error() etc., but with a manual strerror() argument,
>    these should just use the *_errno() helper.
>  * Don't report on the errno at all, e.g. in this case shown here.
> 
> It seems to me that all of these should be using die_errno(),
> error_errno() etc.

Actually, I don't think that's correct.

> Or maybe it's the other way around, and we should not rely on the global
> "errno", but always capture the return value, and give that to
> strerror() (or set "errno = ret", and call {die,error,warning}_errno()).

Yeah, I think we need to do this. That's because unlike most other functions, the pthread functions _don't_ set errno, and instead return the error value. That's why on a typical Unix system, we would have never failed before this patch: because errno values are always positive.

-- 
brian m. carlson (he/him or they/them)
Toronto, Ontario, CA