render/allocator: add allocator_autocreate_with_drm_fd

Same as wlr_allocator_autocreate, but allows the caller to force a
DRM FD.

Similar to renderer_autocreate_with_drm_fd.

include/render/allocator.h

@@ -46,4 +46,7 @@ struct wlr_buffer *wlr_allocator_create_buffer(struct wlr_allocator *alloc,
 void wlr_allocator_init(struct wlr_allocator *alloc,
 	const struct wlr_allocator_interface *impl);
 
+struct wlr_allocator *allocator_autocreate_with_drm_fd(
+	struct wlr_backend *backend, struct wlr_renderer *renderer, int drm_fd);
+
 #endif

render/allocator.c

@@ -18,11 +18,11 @@ void wlr_allocator_init(struct wlr_allocator *alloc,
 	wl_signal_init(&alloc->events.destroy);
 }
 
-struct wlr_allocator *wlr_allocator_autocreate(struct wlr_backend *backend,
+struct wlr_allocator *allocator_autocreate_with_drm_fd(
-		struct wlr_renderer *renderer) {
+		struct wlr_backend *backend, struct wlr_renderer *renderer,
+		int drm_fd) {
 	uint32_t backend_caps = backend_get_buffer_caps(backend);
 	uint32_t renderer_caps = renderer_get_render_buffer_caps(renderer);
-	int drm_fd = wlr_backend_get_drm_fd(backend);
 
 	struct wlr_allocator *alloc = NULL;
 	uint32_t gbm_caps = WLR_BUFFER_CAP_DMABUF;
@@ -51,6 +51,13 @@ struct wlr_allocator *wlr_allocator_autocreate(struct wlr_backend *backend,
 	return NULL;
 }
 
+struct wlr_allocator *wlr_allocator_autocreate(struct wlr_backend *backend,
+		struct wlr_renderer *renderer) {
+	// Note, drm_fd may be negative if unavailable
+	int drm_fd = wlr_backend_get_drm_fd(backend);
+	return allocator_autocreate_with_drm_fd(backend, renderer, drm_fd);
+}
+
 void wlr_allocator_destroy(struct wlr_allocator *alloc) {
 	if (alloc == NULL) {
 		return;