Commit ef7c7ff6 authored by Stefan Hajnoczi's avatar Stefan Hajnoczi
Browse files

qom: add object_property_add_alias() 



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: default avatarStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: default avatarPeter Crosthwaite <peter.crosthwaite@xilinx.com>
parent 53a259da

include/qom/object.h

+20 −0
Original line number Diff line number Diff line
@@ -1230,6 +1230,26 @@ void object_property_add_uint32_ptr(Object *obj, const char *name, 
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

qom/object.c

+51 −0
Original line number Diff line number Diff line
@@ -1550,6 +1550,57 @@ 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);