On Fri, May 23, 2014 at 1:40 AM, Stefan Hajnoczi <stefa...@redhat.com> wrote: > 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 the same object or another object. The source and target > names can be different. > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwa...@xilinx.com> > --- > v2: > * Explain refcount handling in doc comment [Paolo] > * Fix "property" duplicate typo [Peter Crosthwaite] > * Add "the same object or" to clarify commit description [Igor] > --- > include/qom/object.h | 20 ++++++++++++++++++++ > qom/object.c | 52 > ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 72 insertions(+) > > diff --git a/include/qom/object.h b/include/qom/object.h > index a641dcd..854a0d5 100644 > --- a/include/qom/object.h > +++ b/include/qom/object.h > @@ -1203,6 +1203,26 @@ 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 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. In the case of a child object or an alias on the > same > + * object this will be the case. For aliases to other objects the caller is > + * responsible for taking a reference. > + */ > +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); > +} > + > static void object_instance_init(Object *obj) > { > object_property_add_str(obj, "type", qdev_get_type, NULL, NULL); > -- > 1.9.0 > >