[Spice-devel] [PATCH v2] server: Fix conversions between QXLPHYSICAL and pointers
Christophe Fergeau
cfergeau at redhat.com
Mon Jan 11 09:12:42 PST 2016
On Mon, Jan 11, 2016 at 06:07:37PM +0100, Francois Gouget wrote:
> On Mon, 11 Jan 2016, Christophe Fergeau wrote:
> [...]
> > > +#define QXLPHYSICAL_FROM_PTR(ptr) ((QXLPHYSICAL)(intptr_t)(ptr))
> > > +#define QXLPHYSICAL_TO_PTR(ptrtype, phy) ((ptrtype)(intptr_t)(phy))
> >
> > 'ptrtype' still does not seem to bring much compared to:
> >
> > #define QXLPHYSICAL_TO_PTR(phy) ((void*)(intptr_t)(phy))
>
> Without it you cannot write:
>
> info = QXLPHYSICAL_TO_PTR(QXLReleaseInfo*, cmd->cmd.data);
>
> You have to write the following instead:
>
> info = (QXLReleaseInfo*)QXLPHYSICAL_TO_PTR(cmd->cmd.data);
I think in C, void * will be implicitly cast to any other pointer type,
ie info = QXLPHYSICAL_TO_PTR(cmd->cmd.data); should work.
If this causes a warning, then ACK to your version.
> > Is the addition of that (uintptr_t) cast mandatory here? (not really
> > important, just curious).
>
> It is. Without it one gets the following error because cmd is a 32 bit
> QXLCommandExt* pointer:
>
> red-replay-qxl.c: In function 'spice_replay_next_cmd':
> red-replay-qxl.c:1162: error: cast from pointer to integer of different size [-Wpointer-to-int-cast]
>
> Maybe it should go in separately though.
I'm fine with keeping it in this patch.
Christophe
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