Re: [Qemu-devel] [PATCH 2/1] libqtest: add more exit status checks

[Eric Blake <eblake@redhat.com>]

On 05/24/2018 10:17 AM, Michael S. Tsirkin wrote:
> Add more checks on how did QEMU exit.
> 
> Legal ways to exit right now:
> - exit(0) or return from main
> - kill(SIGTERM) - sent by testing infrastructure

Yes, but kill(SIGTERM) causes qemu proper to exit with status 0, because 
we handle the signal rather than letting it have default behavior or 
rethrowing it.

> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Suggested-by: Thomas Huth <thuth@redhat.com>
> ---
> 
> TODO: refactor testing infrastructure to stop
> QEMU through QMP as opposed to SIGTERM.

>           if (pid == s->qemu_pid && WIFSIGNALED(wstatus)) {
> +            /* Core dump is never OK */
>               assert(!WCOREDUMP(wstatus));
> +            /* Either exit normally or get killed */
> +            assert((WIFEXITED(wstatus) || WIFSIGNALED(wstatus)));

Eww. This is true if someone does SIGKILL, but not if someone does SIGTERM.

> +            /* Exited normally - check exit status. */
> +            assert(!WIFEXITED(wstatus) || WEXITSTATUS(wstatus) == 0);

This is fine.

> +            /* Killed - we only ever send SIGTERM. */
> +            assert(!WIFSIGNALED(wstatus) || WTERMSIG(wstatus) == SIGTERM);

But this is bogus.  Sending SIGTERM does NOT cause WIFSIGNALED(); you'd 
be hard-pressed to get qemu to exit with WTERMSIG(wstatus) == SIGTERM.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org