egl-wayland: Make sure we allocate a back buffer even if nothing was rendered

At eglSwapBuffer time, we blindly assume we have a back buffer, but the
back buffer only gets allocated when somebody tries to render something.

NOTE: This is a candidate for the 9.0 and 9.1 branches.

https://bugs.freedesktop.org/show_bug.cgi?id=60086

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index e9a66afb6ed6bd8c09976c54f8079a55857cd036..99d8729cfc19f03e4a6c702d7687fcef730e7efb 100644 (file)
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -446,6 +446,7 @@ dri2_swap_buffers(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *draw)
 {
    struct dri2_egl_display *dri2_dpy = dri2_egl_display(disp);
    struct dri2_egl_surface *dri2_surf = dri2_egl_surface(draw);
+   __DRIbuffer buffer;
    int i, ret = 0;
 
    while (dri2_surf->frame_callback && ret != -1)
@@ -463,6 +464,13 @@ dri2_swap_buffers(_EGLDriver *drv, _EGLDisplay *disp, _EGLSurface *draw)
       if (dri2_surf->color_buffers[i].age > 0)
          dri2_surf->color_buffers[i].age++;
 
+   /* Make sure we have a back buffer in case we're swapping without ever
+    * rendering. */
+   if (get_back_bo(dri2_surf, &buffer) < 0) {
+      _eglError(EGL_BAD_ALLOC, "dri2_swap_buffers");
+      return EGL_FALSE;
+   }
+
    dri2_surf->back->age = 1;
    dri2_surf->current = dri2_surf->back;
    dri2_surf->back = NULL;