[PATCH] dri2: Pass a ScreenPtr through to the driver's AuthMagic

[Christopher James Halse Rogers]

On Fri, 2012-06-15 at 21:54 +1000, Christopher James Halse Rogers wrote:
> 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?
> 
Bah. Yes, of course they are; that's needed for bisecting the X server
at least.

Sorry, too much distro thinking :)

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