[PATCH] dri2: Pass a ScreenPtr through to the driver's AuthMagic
Christopher James Halse Rogers
christopher.halse.rogers at canonical.com
Fri Jun 15 04:54:22 PDT 2012
On Fri, 2012-06-15 at 12:35 +0200, Michel Dänzer wrote:
> On Fre, 2012-06-15 at 19:01 +1000, Christopher James Halse Rogers
> wrote:
> > xwayland drivers need access to their screen private data to authenticate.
> > Now that drivers no longer have direct access to the global screen arrays,
> > this needs to be passed in as function context. The way it was working
> > was ugly, anyway.
> >
> > Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers at canonical.com>
> > ---
> >
> > This came up when I got around to fixing the nouveau xwayland patch review
> > comments; with things no longer meant to access the global xf86Screens array
> > the authmagic callback needed some other way to access driver private data.
> >
> > Nouveau patch using this follows; I'll send it upstream once this gets
> > applied somewhere.
> >
> > CCd to xorg-devel mainly for sanity review, but could be applied; as Airlied
> > has pointed out, there's no particular reason for the xwayland branch to
> > diverge on core infrastructure.
>
> [...]
>
> > @@ -1202,9 +1215,17 @@ DRI2ScreenInit(ScreenPtr pScreen, DRI2InfoPtr info)
> > cur_minor = 1;
> > }
> >
> > - if (info->version >= 5) {
> > + if (info->version >= 7) {
> > ds->AuthMagic = info->AuthMagic;
> > }
> > + else if (info->version >= 5) {
> > + /*
> > + * This cast is safe; if the driver has provided a V5 or V6 InfoRec
> > + * then AuthMagic is of type DRI2LegacyAuthMagicProcPtr, and the C
> > + * standard guarantees that we can typecast it back and call it.
> > + */
> > + ds->LegacyAuthMagic = (DRI2LegacyAuthMagicProcPtr)info->AuthMagic;
> > + }
>
> This is nifty, but it's an ABI break, as servers without this change
> will treat the version 7 AuthMagic field incorrectly. Wouldn't it be
> easier to add a second AuthMagic field at the end of version 7?
The only way a driver would send a version 7 DRI2InfoPtr would be if it
were built against a server with this code, right? Are drivers generally
expected work against a server *older* than they were built against?
It could easily be an extra field in the InfoPtr, of course.
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