[mutter] wayland/dma-buf: Handle zero modifiers from eglQueryDmaBufModifiersEXT

[Jonas Ådahl <jadahl src gnome org>]

commit 031003a5dc8b7f42588196735820028e3cdf2158
Author: Adam Jackson <ajax redhat com>
Date:   Fri Sep 6 14:45:55 2019 -0400

    wayland/dma-buf: Handle zero modifiers from eglQueryDmaBufModifiersEXT
    
    Some drivers expose EGL_EXT_image_dma_buf_import_modifiers so you can
    query supported formats, but don't support any modifiers. Handle this by
    treating it like DRM_FORMAT_MOD_INVALID.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/782

 src/wayland/meta-wayland-dma-buf.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
---
diff --git a/src/wayland/meta-wayland-dma-buf.c b/src/wayland/meta-wayland-dma-buf.c
index e672749e4..914e03a2f 100644
--- a/src/wayland/meta-wayland-dma-buf.c
+++ b/src/wayland/meta-wayland-dma-buf.c
@@ -461,9 +461,17 @@ send_modifiers (struct wl_resource *resource,
    * then fill the array. */
   ret = meta_egl_query_dma_buf_modifiers (egl, egl_display, format, 0, NULL,
                                           NULL, &num_modifiers, NULL);
-  if (!ret || num_modifiers == 0)
+  if (!ret)
     return;
 
+  if (num_modifiers == 0)
+    {
+      zwp_linux_dmabuf_v1_send_modifier (resource, format,
+                                         DRM_FORMAT_MOD_INVALID >> 32,
+                                         DRM_FORMAT_MOD_INVALID & 0xffffffff);
+      return;
+    }
+
   modifiers = g_new0 (uint64_t, num_modifiers);
   ret = meta_egl_query_dma_buf_modifiers (egl, egl_display, format,
                                           num_modifiers, modifiers, NULL,