[libvirt] [PATCH] vbox: avoid provoking assertions in VBoxSVC

[Matthias Bolte]

Am 20. April 2012 01:07 schrieb Eric Blake <eblake at redhat.com>:
> On 04/17/2012 10:50 AM, Eric Blake wrote:
>> On 04/13/2012 07:04 AM, Jean-Baptiste Rouault wrote:
>>> Passing a NULL pointer to IMachine::delete virtualbox API
>>> causes VBoxSVC to raise an assertion. This patch passes
>>> an empty array instead.
>>> ---
>>>  src/vbox/vbox_tmpl.c |    3 ++-
>>>  1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/src/vbox/vbox_tmpl.c b/src/vbox/vbox_tmpl.c
>>> index 68e3b05..be25828 100644
>>> --- a/src/vbox/vbox_tmpl.c
>>> +++ b/src/vbox/vbox_tmpl.c
>>> @@ -5294,7 +5294,8 @@ vboxDomainUndefineFlags(virDomainPtr dom, unsigned int flags)
>>>
>>>          ((IMachine_Delete)machine->vtbl->Delete)(machine, &safeArray, &progress);
>>>  # else
>>> -        machine->vtbl->Delete(machine, 0, NULL, &progress);
>>> +        vboxArray array = VBOX_ARRAY_INITIALIZER;
>>> +        machine->vtbl->Delete(machine, 0, (IMedium**)&array, &progress);
>>>  # endif
>>
>> ACK and Pushed.

Actually, this is not how vboxArray is supposed to be used. vboxArray
is a wrapper with specific implementations for MSCOM and XPCOM. You
cannot just cast it to a VirtualBox API type.

> Phooey.  Now I'm getting compile failure:
>
> cc1: warnings being treated as errors
> In file included from vbox/vbox_V4_0.c:13:
> vbox/vbox_tmpl.c: In function 'vboxDomainUndefineFlags':
> vbox/vbox_tmpl.c:5298: warning: dereferencing type-punned pointer will
> break strict-aliasing rules [-Wstrict-aliasing]

I think we need a new vboxArrayPass/Set function to get this right. I
might have time to take care of this tomorrow, if nobody fixed it
before then.

-- 
Matthias Bolte
http://photron.blogspot.com