wayland-egl: Make wl_egl_window a versioned struct

We need wl_egl_window to be a versioned struct in order to keep track of
ABI changes.

This change makes the first member of wl_egl_window the version number.

An heuristic in the wayland driver is added so that we don't break
backwards compatibility:

 - If the first field (version) is an actual pointer, it is an old
   implementation of wl_egl_window, and version points to the wl_surface
   proxy.

 - Else, the first field is the version number, and we have
   wl_egl_window::surface pointing to the wl_surface proxy.

Signed-off-by: Miguel A. Vico <[email protected]>
Reviewed-by: James Jones <[email protected]>
Acked-by: Daniel Stone <[email protected]>
Reviewed-by: Emil Velikov <[email protected]>

1 files changed, 15 insertions, 1 deletions

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 211036f45f4..f4c09ac0bc1 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -43,6 +43,7 @@
 #include "egl_dri2_fallbacks.h"
 #include "loader.h"
 #include "util/u_vector.h"
+#include "eglglobals.h"
 
 #include <wayland-client.h>
 #include "wayland-drm-client-protocol.h"
@@ -111,6 +112,19 @@ destroy_window_callback(void *data)
    dri2_surf->wl_win = NULL;
 }
 
+static struct wl_surface *
+get_wl_surface_proxy(struct wl_egl_window *window)
+{
+    /* Version 3 of wl_egl_window introduced a version field at the same
+     * location where a pointer to wl_surface was stored. Thus, if
+     * window->version is dereferencable, we've been given an older version of
+     * wl_egl_window, and window->version points to wl_surface */
+   if (_eglPointerIsDereferencable((void *)(window->version))) {
+      return wl_proxy_create_wrapper((void *)(window->version));
+   }
+   return wl_proxy_create_wrapper(window->surface);
+}
+
 /**
  * Called via eglCreateWindowSurface(), drv->API.CreateWindowSurface().
  */
@@ -182,7 +196,7 @@ dri2_wl_create_window_surface(_EGLDriver *drv, _EGLDisplay *disp,
    wl_proxy_set_queue((struct wl_proxy *)dri2_surf->wl_dpy_wrapper,
                       dri2_surf->wl_queue);
 
-   dri2_surf->wl_surface_wrapper = wl_proxy_create_wrapper(window->surface);
+   dri2_surf->wl_surface_wrapper = get_wl_surface_proxy(window);
    if (!dri2_surf->wl_surface_wrapper) {
       _eglError(EGL_BAD_ALLOC, "dri2_create_surface");
       goto cleanup_drm;