[libvirt] [PATCH 3/4] Add support for detecting capablities using QMP commands

[Daniel P. Berrange]

On Fri, Sep 28, 2012 at 09:20:01AM -0600, Eric Blake wrote:
> On 09/28/2012 08:58 AM, Daniel P. Berrange wrote:
> > From: "Daniel P. Berrange" <berrange at redhat.com>
> > 
> > Start a QEMU process using
> > 
> >    $QEMU -S -no-user-config -nodefaults \
> >          -nographic -M none -qmp unix:/some/path,server,nowait
> > 
> > and talk QMP over stdio to discover what capabilities the
> > binary supports. This works for QEMU 1.2.0 or later and
> > for older QEMU automatically fallback to the old approach
> > of parsing -help and related command line args.
> > 
> > Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> > ---
> >  src/qemu/qemu_capabilities.c | 394 +++++++++++++++++++++++++++++++++++++++----
> >  1 file changed, 358 insertions(+), 36 deletions(-)
> > 
> 
> > +
> > +/* Capabilities that we assume are always enabled
> > + * for QEMU >= 1.2.0
> > + */
> > +static void
> > +qemuCapsInitQMPBasic(qemuCapsPtr caps)
> > +{
> > +    qemuCapsSet(caps, QEMU_CAPS_VNC_COLON);
> > +    qemuCapsSet(caps, QEMU_CAPS_NO_REBOOT);
> 
> I think qemuCapsSetList() would be nicer than setting one bit at a time,
> but that doesn't change semantics.
> 
> 
> > +
> > +static int
> > +qemuCapsInitQMP(qemuCapsPtr caps)
> > +{
> > +    int ret = -1;
> > +    virCommandPtr cmd = NULL;
> > +    qemuMonitorPtr mon = NULL;
> > +    int major, minor, micro;
> > +    char *package;
> > +    int status = 0;
> > +    virDomainChrSourceDef config;
> > +
> > +    memset(&config, 0, sizeof(config));
> > +    config.type = VIR_DOMAIN_CHR_TYPE_UNIX;
> > +    config.data.nix.path = (char*)"/tmp/qemu.sock";
> 
> This does not seem like a safe file name (it is easily guessable).
> Should we instead be generating something under /var/run?

Of course it isn't :-( I blame the end of week exhaustion. Locally
I have an addition to make it use driver->libDir, as we do for normal
monitor sockets for actual VMs.


Daniel
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