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Date: Fri, 16 Dec 2011 08:10:26 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 1/8] qapi: fix NULL pointer dereference
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org

On 12/16/2011 08:00 AM, Paolo Bonzini wrote:
> On 12/16/2011 02:55 PM, Anthony Liguori wrote:
>>> This is visible with
>>>
>>> qom-get path=/i440fx/piix3 property=romfile
>>>
>>> after static non-string properties are introduced.
>>
>> I'm a bit confused about what's happening here. What's the significance
>> of non-string properties?
>
> Should have been "static non-legacy properties".
>
> When you don't have a value for a property, legacy properties are visited as
> "<null>", while the new static properties do not pass anything to the visitor.

>
> I stole this from qdev_property_get_str:
>
> value = prop->get(dev, errp);
> if (value) {
> visit_type_str(v, &value, name, errp);
> g_free(value);
> }

I should more clearly document it.  NULL would be only return if errp was set. 
I just didn't want to introduce a local_err in order to be able to check whether 
the function failed.

If a property function does not set the Error pointer, it must visit something.

Regards,

Anthony Liguori

>
> Paolo
>