Re: [Qemu-devel] [PATCH 6/6] tests: exercise NBD server in TLS mode

[Eric Blake]

On 11/19/18 4:37 AM, Daniel P. Berrangé wrote:

> > Actually, I tracked this message down to using socat (which actually
> > connects and then abruptly exits) when probing whether the socket is up and
> > listening.  That is, the message is being produced as a side effect of
> > nbd_server_wait_for_tcp_socket rather than during the actual $QEMU_IMG
> > command we are interested in testing.

> > > This is the first use of socat in iotests.  Might not be the most
> > > portable, but I don't know if I have better ideas.
> > > nbdkit.git/tests/test-ip.sh greps the output of 'ss -ltn' to locate free
> > > ports, but I don't know if ss is any better than socat.
> >
> > So, I'm planning to squash this in, to use ss instead of socat, as follows:
>
> Personally I prefer socat since it is more portable, per my previous
> message.

socat is indeed probably more portable, but since tests 233 uses 
'_supported_os Linux', ss availability isn't a problem until a future 
user ports this test to non-Linux.  I'd like to patch qemu-nbd to NOT 
warn about a user that connects but does not consume data (the socat 
case, as well as port probes), but as that patch does not exist yet and 
-rc2 is getting close, I'll go ahead and send the pull request with ss 
instead of socat.

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