[PATCH 3/4] wl_resource: Add a private field to wl_resource

[alexl at redhat.com]

From: Alexander Larsson <alexl at redhat.com>

This takes the place of the second pointer in the old wl_list and
lets us add more fields to wl_resource in a backwards compat fashion.
---
 src/wayland-private.h |  4 ++++
 src/wayland-server.c  | 17 ++++++++++++++++-
 src/wayland-server.h  |  4 +++-
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/src/wayland-private.h b/src/wayland-private.h
index c4ce6b0..105f9b9 100644
--- a/src/wayland-private.h
+++ b/src/wayland-private.h
@@ -47,6 +47,10 @@ struct wl_map {
 	uint32_t free_list;
 };
 
+struct wl_resource_private {
+	uint32_t dummy;
+};
+
 typedef void (*wl_iterator_func_t)(void *element, void *data);
 
 void wl_map_init(struct wl_map *map);
diff --git a/src/wayland-server.c b/src/wayland-server.c
index f1a6aac..e3a0376 100644
--- a/src/wayland-server.c
+++ b/src/wayland-server.c
@@ -377,6 +377,14 @@ WL_EXPORT uint32_t
 wl_client_add_resource(struct wl_client *client,
 		       struct wl_resource *resource)
 {
+	struct wl_resource_private *priv;
+
+	priv = calloc(1, sizeof(struct wl_resource_private));
+	if (!priv) {
+		wl_resource_post_no_memory(resource);
+		return 0;
+	}
+
 	if (resource->object.id == 0) {
 		resource->object.id =
 			wl_map_insert_new(&client->objects,
@@ -387,9 +395,11 @@ wl_client_add_resource(struct wl_client *client,
 				       WL_DISPLAY_ERROR_INVALID_OBJECT,
 				       "invalid new id %d",
 				       resource->object.id);
+		free(priv);
 		return 0;
 	}
 
+	resource->priv = priv;
 	resource->client = client;
 	wl_signal_init(&resource->destroy_signal);
 
@@ -413,11 +423,15 @@ static void
 destroy_resource(void *element, void *data)
 {
 	struct wl_resource *resource = element;
+	struct wl_resource_private *resource_priv = resource->priv;
 
 	wl_signal_emit(&resource->destroy_signal, resource);
 
 	if (resource->destroy)
 		resource->destroy(resource);
+
+	if (resource_priv != (struct wl_resource_private *)(resource + 1))
+		free (resource_priv);
 }
 
 WL_EXPORT void
@@ -906,13 +920,14 @@ wl_client_add_object(struct wl_client *client,
 {
 	struct wl_resource *resource;
 
-	resource = malloc(sizeof *resource);
+	resource = malloc(sizeof *resource + sizeof (struct wl_resource_private));
 	if (resource == NULL) {
 		wl_resource_post_no_memory(client->display_resource);
 		return NULL;
 	}
 
 	wl_resource_init(resource, interface, implementation, id, data);
+	resource->priv = (struct wl_resource_private *)(resource + 1);
 	resource->client = client;
 	resource->destroy = (void *) free;
 
diff --git a/src/wayland-server.h b/src/wayland-server.h
index 4867652..3ac0351 100644
--- a/src/wayland-server.h
+++ b/src/wayland-server.h
@@ -177,11 +177,13 @@ wl_signal_emit(struct wl_signal *signal, void *data)
 		l->notify(l, data);
 }
 
+struct wl_resource_private;
+
 struct wl_resource {
 	struct wl_object object;
 	void (*destroy)(struct wl_resource *resource);
 	struct wl_slist link;
-	void *reserved;
+	struct wl_resource_private *priv;
 	struct wl_signal destroy_signal;
 	struct wl_client *client;
 	void *data;
-- 
1.8.1.4