Re: [Qemu-devel] [PATCH v2 12/27] qom: add property get/set wrappers for links

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/04/2012 02:02 AM, Paolo Bonzini wrote:
> These can set a link to any object, as long as it is included in
> the composition tree.
>
> Signed-off-by: Paolo Bonzini<pbonzini@redhat.com>
> ---
>   include/qemu/object.h |   24 ++++++++++++++++++++++++
>   qom/object.c          |   25 +++++++++++++++++++++++++
>   2 files changed, 49 insertions(+), 0 deletions(-)
>
> diff --git a/include/qemu/object.h b/include/qemu/object.h
> index 4ec7942..910b767 100644
> --- a/include/qemu/object.h
> +++ b/include/qemu/object.h
> @@ -658,6 +658,30 @@ char *object_property_get_str(Object *obj, const char *name,
>                                 struct Error **errp);
>
>   /**
> + * object_property_set_link:
> + * @value: the value to be written to the property
> + * @name: the name of the property
> + * @errp: returns an error if this function fails
> + *
> + * Writes an object's canonical path to a property.
> + */
> +void object_property_set_link(Object *obj, Object *value,
> +                              const char *name, struct Error **errp);
> +
> +/**
> + * object_property_get_link:
> + * @obj: the object
> + * @name: the name of the property
> + * @errp: returns an error if this function fails
> + *
> + * Returns: the value of the property, resolved from a path to an Object,
> + * or NULL if an error occurs (including when the property value is not a
> + * string or not a valid object path).
> + */
> +Object *object_property_get_link(Object *obj, const char *name,
> +                                 struct Error **errp);
> +
> +/**
>    * object_property_set_bool:
>    * @value: the value to be written to the property
>    * @name: the name of the property
> diff --git a/qom/object.c b/qom/object.c
> index e8418bc..b3cff50 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -710,6 +710,30 @@ char *object_property_get_str(Object *obj, const char *name,
>       return retval;
>   }
>
> +void object_property_set_link(Object *obj, Object *value,
> +                              const char *name, Error **errp)
> +{
> +    object_property_set_str(obj, object_get_canonical_path(value),
> +                            name, errp);
> +}

We could fall back to setting the link directly via the property opaque, but I 
guess that might let us get lazy about filling in the composition tree.

Regards,

Anthony Liguori

> +
> +Object *object_property_get_link(Object *obj, const char *name,
> +                                 Error **errp)
> +{
> +    char *str = object_property_get_str(obj, name, errp);
> +    Object *target = NULL;
> +
> +    if (str&&  *str) {
> +        target = object_resolve_path(str, NULL);
> +        if (!target) {
> +            error_set(errp, QERR_DEVICE_NOT_FOUND, str);
> +        }
> +    }
> +
> +    g_free(str);
> +    return target;
> +}
> +
>   void object_property_set_bool(Object *obj, bool value,
>                                 const char *name, Error **errp)
>   {