Re: passt.c: incorrect signal() return value check

[Stefano Brivio <sbrivio@redhat.com>]

Hi Valtteri,

On Thu, 13 Apr 2023 13:24:34 +0300
Valtteri Vuorikoski <vuori@notcom.org> wrote:

> In current master, passt.c:main() has an incorrect check on signal()
> return value:
> 
>                if (sigaction(SIGCHLD, &sa, NULL) || signal(SIGPIPE, SIG_IGN))
>                        die("Couldn't install signal handlers");
> 
> signal() returns SIG_ERR on failure or the previous setting if present. If
> a setting has been inherited from the parent (as is the case when
> starting from systemd with the default setting of IgnoreSIGPIPE=yes),
> the check will fail.

Right, thanks for reporting this.

By the way, feel free to share your systemd unit files, I guess we
could add them under contrib/ in case they are useful for somebody.

> The if statement should check for SIG_ERR for the SIGPIPE case, or
> alternatively switch to sigaction() since that's used for everything
> else in the code.

I guess we could just check SIG_ERR from signal(), it looks a bit
simpler, and perhaps split this into two cases (a failure on signal()
doesn't mean we "[c]ouldn't install signal handlers").

Will you post a patch? It's trivial, so if it's unnecessary effort for
you I can also go ahead and do it.

>  -Valtteri
>  (please cc on replies)

-- 
Stefano