[libvirt] [PATCH 4/4] Implement virDomainSendProcessSignal for LXC driver

[Eric Blake]

> Implement the new API for sending signals to processes in a guest
> for the LXC driver. Only support sending signals to the init
> process for now, because
> 
>  - The kernel does not appear to expose the mapping between
>    container PID numbers and host PID numbers anywhere in the
>    host OS namespace
>  - There is no race-free validate whether a host PID corresponds

s/race-free/race-free way to/

> +    /* We're relying on fact libvirt header signal numbers
> +     * are taken from Linux, to avoid mapping

Cute, but at least you documented your assumption.  Should you
validate that signum <= SIGRTMAX, though, for a nicer error
than what kill() would give for out-of-range signum?