qom: New object_property_add_new_container()

To move towards explicit creations of containers, starting that by
providing a helper for creating container objects.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20241121192202.4155849-3-peterx@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

include/qom/object.h

@@ -2019,6 +2019,18 @@ int object_child_foreach_recursive(Object *obj,
  */
 Object *container_get(Object *root, const char *path);
 
+/**
+ * object_property_add_new_container:
+ * @obj: the parent object
+ * @name: the name of the parent object's property to add
+ *
+ * Add a newly created container object to a parent object.
+ *
+ * Returns: the newly created container object.  Its reference count is 1,
+ * and the reference is owned by the parent object.
+ */
+Object *object_property_add_new_container(Object *obj, const char *name);
+
 /**
  * object_property_help:
  * @name: the name of the property

qom/container.c

@@ -24,6 +24,16 @@ static void container_register_types(void)
     type_register_static(&container_info);
 }
 
+Object *object_property_add_new_container(Object *obj, const char *name)
+{
+    Object *child = object_new(TYPE_CONTAINER);
+
+    object_property_add_child(obj, name, child);
+    object_unref(child);
+
+    return child;
+}
+
 Object *container_get(Object *root, const char *path)
 {
     Object *obj, *child;
@@ -37,9 +47,7 @@ Object *container_get(Object *root, const char *path)
     for (i = 1; parts[i] != NULL; i++, obj = child) {
         child = object_resolve_path_component(obj, parts[i]);
         if (!child) {
-            child = object_new(TYPE_CONTAINER);
+            child = object_property_add_new_container(obj, parts[i]);
-            object_property_add_child(obj, parts[i], child);
-            object_unref(child);
         }
     }