Add a shorthand for creating an alias of a child<> property. If you
pass a NULL target_name to object_property_add_alias, the function
will look up the child property that leads to target_obj, and create
an alias for that property.
This can be useful when an object wants to add a link to itself
at a well-known location. For example, a real-time clock device might
add a link to itself at "/machine/rtc". Such well-known locations can
then expose a standard set of properties that can be accessed via the
"qom-get" and "qom-set" commands.
Signed-off-by: Paolo Bonzini <address@hidden>
---
include/qom/object.h | 10 +++++++---
qom/object.c | 16 +++++++++++++---
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/include/qom/object.h b/include/qom/object.h
index 9c4a5a4..9cd0ffa 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -1256,11 +1256,15 @@ void object_property_add_uint64_ptr(Object *obj, const
char *name,
* @obj: the object to add a property to
* @name: the name of the property
* @target_obj: the object to forward property access to
- * @target_name: the name of the property on the forwarded object
+ * @target_name: the name of the property on the forwarded object, or
+ * #NULL to make an object alias.
* @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.
+ * Add an alias property on an object. This function will add a property
+ * of the same type as the forwarded property or, if @target_name is #NULL,
+ * a link property that always resolves to @target_obj. In fact, the case
+ * of a #NULL @target_obj actually creates an alias property that targets
+ * @target_obj's own child property.
*
* The caller must ensure that <code>@target_obj</code> stays alive as long as
* this property exists. In the case of a child object or an alias on the same
diff --git a/qom/object.c b/qom/object.c
index ddf781e..1e8e6af 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1535,7 +1535,7 @@ void object_property_add_uint64_ptr(Object *obj, const
char *name,
typedef struct
{
Object *target_obj;
- const char *target_name;
+ char *target_name;
} AliasProperty;
static void property_get_alias(Object *obj, struct Visitor *v, void *opaque,
@@ -1566,6 +1566,7 @@ static void property_release_alias(Object *obj, const
char *name, void *opaque)
{
AliasProperty *prop = opaque;
+ g_free(prop->target_name);
g_free(prop);
}
@@ -1576,9 +1577,18 @@ void object_property_add_alias(Object *obj, const char
*name,
AliasProperty *prop;
ObjectProperty *target_prop;
gchar *prop_type;
+ gchar *the_target_name;
- target_prop = object_property_find(target_obj, target_name, errp);
+ if (!target_name) {
+ the_target_name = object_get_canonical_path_component(target_obj);
+ target_obj = target_obj->parent;