[libvirt] [PATCH] qemu: Let empty default VNC password work as documented

[Cole Robinson]

On 06/28/2016 09:28 AM, Daniel P. Berrange wrote:
> On Tue, Jun 28, 2016 at 02:45:15PM +0200, Jiri Denemark wrote:
>> Setting an empty vnc_password in qemu.conf is documented as a way to
>> disable VNC access, but QEMU does not seem to behave like that. Let's
>> enforce the behavior by setting password expiration to "now".
> 
> Hmm, i wonder when they regressed that behaviour *again*. We've fixed
> that in QEMU at least twice in the past. I'd like to see us explore
> when this changed in QEMU and whehter we should fix it there instead.
> 

I did some digging on this recently, see my findings here:
https://bugzilla.redhat.com/show_bug.cgi?id=1180092#c5

The issue is that there's two different monitor commands at play here, and the
set_password one we presently use has never had the semantics we advertise in
qemu.conf, so I'm guessing something like Jiri's patch will be needed regardless

- Cole