[libvirt-users] Bug? virGetLastError() returns NULL after virDomainCreate() if Domain running already

[Guido Winkelmann]

Am Mittwoch, 22. Februar 2012, 11:26:50 schrieb Eric Blake:
> On 02/22/2012 11:16 AM, Eric Blake wrote:
> > On 02/22/2012 07:06 AM, Guido Winkelmann wrote:
> >> Hi,
> >> 
> >> As the subject line indicates, when I'm calling virDomainCreate() to
> >> start a defined domain, and that command fails because the domain is
> >> already running at that point, virGetLastError() will return NULL,
> >> instead of a proper pointer to an error code.
> >> Libvirt will, however, print an error to the console:
> >> 
> >> libvir: QEMU error : Requested operation is not valid: domain is already
> >> running
> > 
> > Any return of NULL without a last error set is a bug.  I'm trying to
> > chase this down, and hope to have a patch soon.
> 
> I can't reproduce this.  I tested on libvirt 0.9.10, starting with an
> inactive domain 'dom' and using 'virsh dumpxml dom > dom.xml; virsh
> create dom.xml; virsh create dom.xml', and the second create gave me a
> proper error message of "Requested operation is not valid: domain is
> already active as 'dom'".

I cannot reproduce it with virsh either. The problem occured with the C API, 
maybe virsh does some extra testing before start a domain?

Also note that my case did not involve redefining the domain with a new XML 
definition, just starting a domain that had already been defined before.
 
> Can you post the code snippet you are using to get this situation?

Unfortunately, the problem occurs inside a fairly large, and unfortunately not 
Open-Source, C++ program. I will try to reduce it to a minimal testcase as 
soon as I get around to it.

> Could it be that you have a different name and/or UUID in the xml from
> the domain already running (my test obviously reused the same name and
> uuid from what is already running).

No. I'm essentially just using virDomainLookupByName() and then calling 
virDomainCreate() on the returned value. I'm not even touching any uuids.

	Guido