backend/drm: support multi-planar DMA-BUFs when exporting

backend/drm/drm.c

@@ -270,8 +270,7 @@ static bool drm_connector_export_dmabuf(struct wlr_output *output,
 	struct wlr_drm_plane *plane = crtc->primary;
 	struct wlr_drm_surface *surf = &plane->surf;
 
-	export_drm_bo(surf->back, attribs);
-	return true;
+	return export_drm_bo(surf->back, attribs);
 }
 
 static void drm_connector_start_renderer(struct wlr_drm_connector *conn) {

backend/drm/renderer.c

@@ -160,17 +160,33 @@ void post_drm_surface(struct wlr_drm_surface *surf) {
 	}
 }
 
-void export_drm_bo(struct gbm_bo *bo,
+bool export_drm_bo(struct gbm_bo *bo,
 		struct wlr_dmabuf_buffer_attribs *attribs) {
 	memset(attribs, 0, sizeof(struct wlr_dmabuf_buffer_attribs));
-	attribs->n_planes = 1;
+
+	attribs->n_planes = gbm_bo_get_plane_count(bo);
+	if (attribs->n_planes > WLR_LINUX_DMABUF_MAX_PLANES) {
+		return false;
+	}
+
 	attribs->width = gbm_bo_get_width(bo);
 	attribs->height = gbm_bo_get_height(bo);
 	attribs->format = gbm_bo_get_format(bo);
-	attribs->offset[0] = 0;
-	attribs->stride[0] = gbm_bo_get_stride_for_plane(bo, 0);
-	attribs->modifier[0] = DRM_FORMAT_MOD_LINEAR;
-	attribs->fd[0] = gbm_bo_get_fd(bo);
+
+	for (int i = 0; i < attribs->n_planes; ++i) {
+		attribs->offset[i] = gbm_bo_get_offset(bo, i);
+		attribs->stride[i] = gbm_bo_get_stride_for_plane(bo, i);
+		attribs->modifier[i] = gbm_bo_get_modifier(bo);
+		attribs->fd[i] = gbm_bo_get_fd(bo);
+		if (attribs->fd[i] < 0) {
+			for (int j = 0; j < i; ++j) {
+				close(attribs->fd[j]);
+			}
+			return false;
+		}
+	}
+
+	return true;
 }
 
 struct tex {
@@ -200,7 +216,10 @@ static struct wlr_texture *get_tex_for_bo(struct wlr_drm_renderer *renderer,
 	}
 
 	struct wlr_dmabuf_buffer_attribs attribs;
-	export_drm_bo(bo, &attribs);
+	if (!export_drm_bo(bo, &attribs)) {
+		free(tex);
+		return NULL;
+	}
 
 	tex->tex = wlr_texture_from_dmabuf(renderer->wlr_rend, &attribs);
 	if (tex->tex == NULL) {

include/backend/drm/renderer.h

@@ -52,7 +52,7 @@ struct gbm_bo *get_drm_surface_front(struct wlr_drm_surface *surf);
 void post_drm_surface(struct wlr_drm_surface *surf);
 struct gbm_bo *copy_drm_surface_mgpu(struct wlr_drm_surface *dest,
 	struct gbm_bo *src);
-void export_drm_bo(struct gbm_bo *bo,
+bool export_drm_bo(struct gbm_bo *bo,
 	struct wlr_dmabuf_buffer_attribs *attribs);
 
 #endif