Sometimes an object needs to present a property which is actually on
another object, or it needs to provide an alias name for an existing
property.
Examples:
a.foo -> b.foo
a.old_name -> a.new_name
The new object_property_add_alias() API allows objects to alias a
property on another object. The source and target names can be
different.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
include/qom/object.h | 18 ++++++++++++++++++
qom/object.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 70 insertions(+)
diff --git a/include/qom/object.h b/include/qom/object.h
index a641dcd..70cbd13 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -1203,6 +1203,24 @@ void object_property_add_uint64_ptr(Object *obj, const
char *name,
const uint64_t *v, Error **Errp);
/**
+ * object_property_add_alias:
+ * @obj: the object to add a property to
+ * @name: the name of the property
+ * @target_obj: the object to forward property access property to
+ * @target_name: the name of the property on the forwarded object
+ * @errp: if an error occurs, a pointer to an area to store the error
+ *
+ * Add an alias for a property on an object. This function will add a property
+ * of the same type as the forwarded property.
+ *
+ * The caller must ensure that <code>@target_obj</code> stays alive as long as
+ * this property exists.
+ */
+void object_property_add_alias(Object *obj, const char *name,
+ Object *target_obj, const char *target_name,
+ Error **errp);
+
+/**
* object_child_foreach:
* @obj: the object whose children will be navigated
* @fn: the iterator function to be called
diff --git a/qom/object.c b/qom/object.c
index e42b254..ff50f37 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1515,6 +1515,58 @@ void object_property_add_uint64_ptr(Object *obj, const
char *name,
NULL, NULL, (void *)v, errp);
}
+typedef struct
+{
+ Object *target_obj;
+ const char *target_name;
+} AliasProperty;
+
+static void property_get_alias(Object *obj, struct Visitor *v, void *opaque,
+ const char *name, Error **errp)
+{
+ AliasProperty *prop = opaque;
+
+ object_property_get(prop->target_obj, v, prop->target_name, errp);
+}
+
+static void property_set_alias(Object *obj, struct Visitor *v, void *opaque,
+ const char *name, Error **errp)
+{
+ AliasProperty *prop = opaque;
+
+ object_property_set(prop->target_obj, v, prop->target_name, errp);
+}
+
+static void property_release_alias(Object *obj, const char *name, void *opaque)
+{
+ AliasProperty *prop = opaque;
+
+ g_free(prop);
+}
+
+void object_property_add_alias(Object *obj, const char *name,
+ Object *target_obj, const char *target_name,
+ Error **errp)
+{
+ AliasProperty *prop;
+ ObjectProperty *target_prop;
+
+ target_prop = object_property_find(target_obj, target_name, errp);
+ if (!target_prop) {
+ return;
+ }
+
+ prop = g_malloc(sizeof(*prop));
+ prop->target_obj = target_obj;
+ prop->target_name = target_name;
+
+ object_property_add(obj, name, target_prop->type,
+ property_get_alias,
+ property_set_alias,
+ property_release_alias,
+ prop, errp);
+}