[PATCH v2] Add VM info to improve error log message for qemu monitor

[Peter Krempa]

On Tue, Jan 04, 2022 at 14:10:49 +0530, Rohit Kumar wrote:
> 
> On 03/01/22 10:12 pm, Peter Krempa wrote:
> > On Wed, Dec 22, 2021 at 22:39:21 -0800, Rohit Kumar wrote:
> > > This patch is to determine the VM which had IO or socket hangup error.
> > > Accessing directly vm->def->name inside qemuMonitorIO() or qemuMonitorSend()
> > > might leads to illegal access as we are out of 'vm' context and vm->def might
> > > not exist. Adding a field "domainName" inside mon object to access vm name
> > > and initialising it when creating mon object.
> > > 
> > > Signed-off-by: Rohit Kumar <rohit.kumar3 at nutanix.com>
> > > ---

[...]

> > > @@ -609,13 +616,14 @@ qemuMonitorIO(GSocket *socket G_GNUC_UNUSED,
> > >               virResetLastError();
> > >           } else {
> > >               if (virGetLastErrorCode() == VIR_ERR_OK && !mon->goteof)
> > > -                virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> > > -                               _("Error while processing monitor IO"));
> > > +                virReportError(VIR_ERR_INTERNAL_ERROR,
> > > +                               _("%s: Error while processing monitor IO"), NULLSTR(vmName));
> > Same here. Additionally did you ever get to a situation where vmName
> > would be NULL?
> There might be a situation when g_strdup() fails to allocate vm name, for
> e.g. if host ran out of memory ?

No, g_strdup on out of memory condition abort()s the program completely.

The only time when g_strdup returns NULL is if the argument is NULL.

> Let me know your thoughts on this, I would be happy to remove NULLSTR if
> it's not the case.

That depends if you happened to see whether all callers avoid passing
NULL name for the VM which is very likely.