Re: [PATCH 03/12] qom: Make object_class_property_add_uint*_ptr() get offset

From: Eduardo Habkost <ehabkost@redhat.com>
To: Eric Blake <eblake@redhat.com>
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	qemu-devel@nongnu.org, "Markus Armbruster" <armbru@redhat.com>,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"John Snow" <jsnow@redhat.com>
Subject: Re: [PATCH 03/12] qom: Make object_class_property_add_uint*_ptr() get offset
Date: Fri, 9 Oct 2020 13:31:36 -0400	[thread overview]
Message-ID: <20201009173136.GD7303@habkost.net> (raw)
In-Reply-To: <eeb91413-2a1e-5c83-e756-11dbe3be1b6f@redhat.com>

On Fri, Oct 09, 2020 at 12:24:19PM -0500, Eric Blake wrote:
> On 10/9/20 11:01 AM, Eduardo Habkost wrote:
> > The existing object_class_property_add_uint*_ptr() functions are
> > not very useful, because they need a pointer to the property
> > value, which can't really be provided before the object is
> > created.
> > 
> > Replace the pointer parameter in those functions with a
> > `ptrdiff_t offset` parameter.
> > 
> > Include a uint8 class property in check-qom-proplist unit tests,
> > to ensure the feature is working.
> > 
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> 
> >  static void *pointer_property_get_ptr(Object *obj, PointerProperty *prop)
> >  {
> > -    return prop->ptr;
> > +    if (prop->is_offset) {
> > +        return (void *)obj + prop->offset;
> 
> Addition on void* is a gcc extension.  Does clang support it as well, or
> should you be casting to char* instead?

Both object_link_get_targetp() and object_link_get_targetp()
already use it, so it should be OK.

-- 
Eduardo