libvirt users - Oct 2010 - undefining and redefining a Domain

<resending as I don't think I was in the mailing list yet when I sent
first time... apologies if you receive this twice>

 

Hello,

I'm facing some strange behavior, and I hope you can provide a
clarification. 

Consider the following code:

 

     virDomainPtr dom = virDomainLookupByName(virt, domain_name);

     if (dom) {

           printf("domain already defined...\n");

           if (virDomainUndefine(dom))

                printf("...unable to undefine!!!\n");

           else {

                printf("...undefined.");

                free(dom);

           }

     }

     dom = virDomainDefineXML(virt, SOME_XML);

     if (dom != NULL) {

           const char *name = virDomainGetName(dom);

           printf("NAME IS NOW: %s\n", name);

     } else

           printf("dom is NULL!\n");

 

When executed the first time, the code correctly defines the domain, and
prints:

 

defining domain test2-vm

libvir: QEMU error : Domain not found: no domain with matching name
'test2-vm'

NAME IS NOW: test2-vm

 

If executed a second time with  the same SOME_XML when the domain is
already defined, it prints:

 

defining domain test2-vm

domain already defined...

libvir: Domain error : invalid domain pointer in virDomainGetName

undefining......undefined.NAME IS NOW: (null)

 

Not only the name is null, but the domain can't be started. What is the
correct way to undefined programmatically a domain that is already
defined? Why is the second virDomainDefineXML() returining a pointer (as
opposed to null), but the pointed object seem to be invalid?

 

Thanks, 

                 Roberto

 

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2010/10/1 Roberto Attias (rattias) <rattias at
cisco.com>:
> <resending as I don?t think I was in the mailing list yet when I sent
first
> time? apologies if you receive this twice>
>
>
>
> Hello,
>
> I?m facing some strange behavior, and I hope you can provide a
> clarification.
>
> Consider the following code:
>
>
>
> ???? virDomainPtr dom = virDomainLookupByName(virt, domain_name);
>
> ???? if (dom) {
>
> ?????????? printf("domain already defined...\n");
>
> ?????????? if (virDomainUndefine(dom))
>
> ??????????????? printf("...unable to undefine!!!\n");
>
> ?????????? else {
>
> ??????????????? printf("...undefined.");
>
> ??????????????? free(dom);
>
> ?????????? }
>
> ???? }
You're leaking a virDomainPtr here. Call virDomainFree(dom) before
overwriting the pointer with the result from virDomainDefineXML.

I think the leaked virDomainPtr causes the trouble you describe. So
fixing the leak will probably also fix the problem you see in the
second run.
> ???? dom = virDomainDefineXML(virt, SOME_XML);
>
Matthias