Fix leaked extension info on library unload

In this sequence:
dlopen(libvdpau.so)
vdp_device_create_x11(dpy, ...)
dlclose(libvdpau.so)
XCloseDisplay(dpy)

the process will attempt to call the address at which DRI2CloseDisplay
was previously mapped, possibly resulting in a SEGV.

Instead of tracking displays to which we've added hooks and cleaning up
the extension on library unload or display close, simply clean up after
ourselves once we have the data we need.
Signed-off-by: Robert Morell <rmorell@nvidia.com>
Reviewed-by: Aaron Plattner <aplattner@nvidia.com>
Tested-by: Aaron Plattner <aplattner@nvidia.com>
Signed-off-by: Aaron Plattner <aplattner@nvidia.com>

src/mesa_dri2.c

@@ -42,7 +42,6 @@
 
 static char dri2ExtensionName[] = DRI2_NAME;
 static XExtensionInfo *dri2Info;
-static XEXT_GENERATE_CLOSE_DISPLAY (DRI2CloseDisplay, dri2Info)
 
 static /* const */ XExtensionHooks dri2ExtensionHooks = {
   NULL,                   /* create_gc */
@@ -51,7 +50,7 @@ static /* const */ XExtensionHooks dri2ExtensionHooks = {
   NULL,                   /* free_gc */
   NULL,                   /* create_font */
   NULL,                   /* free_font */
-  DRI2CloseDisplay,       /* close_display */
+  NULL,                   /* close_display */
   NULL,                   /* wire_to_event */
   NULL,                   /* event_to_wire */
   NULL,                   /* error */
@@ -75,6 +74,14 @@ _vdp_DRI2QueryExtension(Display * dpy, int *eventBase, int *errorBase)
       return True;
    }
 
+   if (dri2Info) {
+      if (info) {
+         XextRemoveDisplay(dri2Info, dpy);
+      }
+      XextDestroyExtension(dri2Info);
+      dri2Info = NULL;
+   }
+
    return False;
 }
 
@@ -161,3 +168,11 @@ _vdp_DRI2Connect(Display * dpy, XID window, char **driverName, char **deviceName
 
    return True;
 }
+
+void
+_vdp_DRI2RemoveExtension(Display * dpy)
+{
+   XextRemoveDisplay(dri2Info, dpy);
+   XextDestroyExtension(dri2Info);
+   dri2Info = NULL;
+}

src/mesa_dri2.h

@@ -47,4 +47,7 @@ extern Bool
 _vdp_DRI2Connect(Display * display, XID window, char **driverName,
                  char **deviceName);
 
+extern void
+_vdp_DRI2RemoveExtension(Display * display);
+
 #endif

src/vdpau_wrapper.c

@@ -86,14 +86,17 @@ static char * _vdp_get_driver_name_from_dri2(
 
     if (!_vdp_DRI2QueryVersion(display, &major, &minor) ||
             (major < 1 || (major == 1 && minor < 2))) {
+        _vdp_DRI2RemoveExtension(display);
         return NULL;
     }
 
     if (!_vdp_DRI2Connect(display, root, &driver_name, &device_name)) {
+        _vdp_DRI2RemoveExtension(display);
         return NULL;
     }
 
     XFree(device_name);
+    _vdp_DRI2RemoveExtension(display);
 #endif /* DRI2 */
     return driver_name;
 }