Archipelago » qemu

/*

 * QEMU Object Model

 *

 * Copyright IBM, Corp. 2011

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */

#include "qemu/object.h"

#include "qemu-common.h"

#include "qapi/qapi-visit-core.h"

/* TODO: replace QObject with a simpler visitor to avoid a dependency

 * of the QOM core on QObject?  */

#include "qemu/qom-qobject.h"

#include "qobject.h"

#include "qbool.h"

#include "qint.h"

#include "qstring.h"

#define MAX_INTERFACES 32

typedef struct InterfaceImpl InterfaceImpl;

typedef struct TypeImpl TypeImpl;

struct InterfaceImpl

{

    const char *parent;

    void (*interface_initfn)(ObjectClass *class, void *data);

    TypeImpl *type;

};

struct TypeImpl

{

    const char *name;

    size_t class_size;

    size_t instance_size;

    void (*class_init)(ObjectClass *klass, void *data);

    void (*class_finalize)(ObjectClass *klass, void *data);

    void *class_data;

    void (*instance_init)(Object *obj);

    void (*instance_finalize)(Object *obj);

    bool abstract;

    const char *parent;

    TypeImpl *parent_type;

    ObjectClass *class;

    int num_interfaces;

    InterfaceImpl interfaces[MAX_INTERFACES];

};

typedef struct Interface

{

    Object parent;

    Object *obj;

} Interface;

#define INTERFACE(obj) OBJECT_CHECK(Interface, obj, TYPE_INTERFACE)

static Type type_interface;

static GHashTable *type_table_get(void)

{

    static GHashTable *type_table;

    if (type_table == NULL) {

        type_table = g_hash_table_new(g_str_hash, g_str_equal);

    }

    return type_table;

}

static void type_table_add(TypeImpl *ti)

{

    g_hash_table_insert(type_table_get(), (void *)ti->name, ti);

}

static TypeImpl *type_table_lookup(const char *name)

{

    return g_hash_table_lookup(type_table_get(), name);

}

TypeImpl *type_register(const TypeInfo *info)

{

    TypeImpl *ti = g_malloc0(sizeof(*ti));

    g_assert(info->name != NULL);

    if (type_table_lookup(info->name) != NULL) {

        fprintf(stderr, "Registering `%s' which already exists\n", info->name);

        abort();

    }

    ti->name = g_strdup(info->name);

    ti->parent = g_strdup(info->parent);

    ti->class_size = info->class_size;

    ti->instance_size = info->instance_size;

    ti->class_init = info->class_init;

    ti->class_finalize = info->class_finalize;

    ti->class_data = info->class_data;

    ti->instance_init = info->instance_init;

    ti->instance_finalize = info->instance_finalize;

    ti->abstract = info->abstract;

    if (info->interfaces) {

        int i;

        for (i = 0; info->interfaces[i].type; i++) {

            ti->interfaces[i].parent = info->interfaces[i].type;

            ti->interfaces[i].interface_initfn = info->interfaces[i].interface_initfn;

            ti->num_interfaces++;

        }

    }

    type_table_add(ti);

    return ti;

}

TypeImpl *type_register_static(const TypeInfo *info)

{

    return type_register(info);

}

static TypeImpl *type_get_by_name(const char *name)

{

    if (name == NULL) {

        return NULL;

    }

    return type_table_lookup(name);

}

static TypeImpl *type_get_parent(TypeImpl *type)

{

    if (!type->parent_type && type->parent) {

        type->parent_type = type_get_by_name(type->parent);

        g_assert(type->parent_type != NULL);

    }

    return type->parent_type;

}

static bool type_has_parent(TypeImpl *type)

{

    return (type->parent != NULL);

}

static size_t type_class_get_size(TypeImpl *ti)

{

    if (ti->class_size) {

        return ti->class_size;

    }

    if (type_has_parent(ti)) {

        return type_class_get_size(type_get_parent(ti));

    }

    return sizeof(ObjectClass);

}

static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)

{

    TypeInfo info = {

        .instance_size = sizeof(Interface),

        .parent = iface->parent,

        .class_size = sizeof(InterfaceClass),

        .class_init = iface->interface_initfn,

        .abstract = true,

    };

    char *name = g_strdup_printf("<%s::%s>", ti->name, iface->parent);

    info.name = name;

    iface->type = type_register(&info);

    g_free(name);

}

static void type_class_init(TypeImpl *ti)

{

    size_t class_size = sizeof(ObjectClass);

    int i;

    if (ti->class) {

        return;

    }

    ti->class_size = type_class_get_size(ti);

    ti->class = g_malloc0(ti->class_size);

    ti->class->type = ti;

    if (type_has_parent(ti)) {

        TypeImpl *parent = type_get_parent(ti);

        type_class_init(parent);

        class_size = parent->class_size;

        g_assert(parent->class_size <= ti->class_size);

        memcpy((void *)ti->class + sizeof(ObjectClass),

               (void *)parent->class + sizeof(ObjectClass),

               parent->class_size - sizeof(ObjectClass));

    }

    memset((void *)ti->class + class_size, 0, ti->class_size - class_size);

    for (i = 0; i < ti->num_interfaces; i++) {

        type_class_interface_init(ti, &ti->interfaces[i]);

    }

    if (ti->class_init) {

        ti->class_init(ti->class, ti->class_data);

    }

}

static void object_interface_init(Object *obj, InterfaceImpl *iface)

{

    TypeImpl *ti = iface->type;

    Interface *iface_obj;

    iface_obj = INTERFACE(object_new(ti->name));

    iface_obj->obj = obj;

    obj->interfaces = g_slist_prepend(obj->interfaces, iface_obj);

}

static void object_init_with_type(Object *obj, TypeImpl *ti)

{

    int i;

    if (type_has_parent(ti)) {

        object_init_with_type(obj, type_get_parent(ti));

    }

    for (i = 0; i < ti->num_interfaces; i++) {

        object_interface_init(obj, &ti->interfaces[i]);

    }

    if (ti->instance_init) {

        ti->instance_init(obj);

    }

}

void object_initialize_with_type(void *data, TypeImpl *type)

{

    Object *obj = data;

    g_assert(type != NULL);

    g_assert(type->instance_size >= sizeof(ObjectClass));

    type_class_init(type);

    g_assert(type->abstract == false);

    memset(obj, 0, type->instance_size);

    obj->class = type->class;

    QTAILQ_INIT(&obj->properties);

    object_init_with_type(obj, type);

}

void object_initialize(void *data, const char *typename)

{

    TypeImpl *type = type_get_by_name(typename);

    object_initialize_with_type(data, type);

}

static void object_property_del_all(Object *obj)

{

    while (!QTAILQ_EMPTY(&obj->properties)) {

        ObjectProperty *prop = QTAILQ_FIRST(&obj->properties);

        QTAILQ_REMOVE(&obj->properties, prop, node);

        if (prop->release) {

            prop->release(obj, prop->name, prop->opaque);

        }

        g_free(prop->name);

        g_free(prop->type);

        g_free(prop);

    }

}

static void object_property_del_child(Object *obj, Object *child, Error **errp)

{

    ObjectProperty *prop;

    QTAILQ_FOREACH(prop, &obj->properties, node) {

        if (!strstart(prop->type, "child<", NULL)) {

            continue;

        }

        if (prop->opaque == child) {

            object_property_del(obj, prop->name, errp);

        }

    }

}

void object_unparent(Object *obj)

{

    if (obj->parent) {

        object_property_del_child(obj->parent, obj, NULL);

    }

}

static void object_deinit(Object *obj, TypeImpl *type)

{

    if (type->instance_finalize) {

        type->instance_finalize(obj);

    }

    while (obj->interfaces) {

        Interface *iface_obj = obj->interfaces->data;

        obj->interfaces = g_slist_delete_link(obj->interfaces, obj->interfaces);

        object_delete(OBJECT(iface_obj));

    }

    if (type_has_parent(type)) {

        object_deinit(obj, type_get_parent(type));

    }

    object_unparent(obj);

}

void object_finalize(void *data)

{

    Object *obj = data;

    TypeImpl *ti = obj->class->type;

    object_deinit(obj, ti);

    object_property_del_all(obj);

    g_assert(obj->ref == 0);

}

Object *object_new_with_type(Type type)

{

    Object *obj;

    g_assert(type != NULL);

    obj = g_malloc(type->instance_size);

    object_initialize_with_type(obj, type);

    object_ref(obj);

    return obj;

}

Object *object_new(const char *typename)

{

    TypeImpl *ti = type_get_by_name(typename);

    return object_new_with_type(ti);

}

void object_delete(Object *obj)

{

    object_unref(obj);

    g_assert(obj->ref == 0);

    g_free(obj);

}

static bool type_is_ancestor(TypeImpl *type, TypeImpl *target_type)

{

    assert(target_type);

    /* Check if typename is a direct ancestor of type */

    while (type) {

        if (type == target_type) {

            return true;

        }

        type = type_get_parent(type);

    }

    return false;

}

static bool object_is_type(Object *obj, TypeImpl *target_type)

{

    return !target_type || type_is_ancestor(obj->class->type, target_type);

}

Object *object_dynamic_cast(Object *obj, const char *typename)

{

    TypeImpl *target_type = type_get_by_name(typename);

    GSList *i;

    /* Check if typename is a direct ancestor.  Special-case TYPE_OBJECT,

     * we want to go back from interfaces to the parent.

    */

    if (target_type && object_is_type(obj, target_type)) {

        return obj;

    }

    /* Check if obj is an interface and its containing object is a direct

     * ancestor of typename.  In principle we could do this test at the very

     * beginning of object_dynamic_cast, avoiding a second call to

     * object_is_type.  However, casting between interfaces is relatively

     * rare, and object_is_type(obj, type_interface) would fail almost always.

     *

     * Perhaps we could add a magic value to the object header for increased

     * (run-time) type safety and to speed up tests like this one.  If we ever

     * do that we can revisit the order here.

     */

    if (object_is_type(obj, type_interface)) {

        assert(!obj->interfaces);

        obj = INTERFACE(obj)->obj;

        if (object_is_type(obj, target_type)) {

            return obj;

        }

    }

    if (!target_type) {

        return obj;

    }

    /* Check if obj has an interface of typename */

    for (i = obj->interfaces; i; i = i->next) {

        Interface *iface = i->data;

        if (object_is_type(OBJECT(iface), target_type)) {

            return OBJECT(iface);

        }

    }

    return NULL;

}

static void register_interface(void)

{

    static TypeInfo interface_info = {

        .name = TYPE_INTERFACE,

        .instance_size = sizeof(Interface),

        .abstract = true,

    };

    type_interface = type_register_static(&interface_info);

}

device_init(register_interface);

Object *object_dynamic_cast_assert(Object *obj, const char *typename)

{

    Object *inst;

    inst = object_dynamic_cast(obj, typename);

    if (!inst) {

        fprintf(stderr, "Object %p is not an instance of type %s\n",

                obj, typename);

        abort();

    }

    return inst;

}

ObjectClass *object_class_dynamic_cast(ObjectClass *class,

                                       const char *typename)

{

    TypeImpl *target_type = type_get_by_name(typename);

    TypeImpl *type = class->type;

    while (type) {

        if (type == target_type) {

            return class;

        }

        type = type_get_parent(type);

    }

    return NULL;

}

ObjectClass *object_class_dynamic_cast_assert(ObjectClass *class,

                                              const char *typename)

{

    ObjectClass *ret = object_class_dynamic_cast(class, typename);

    if (!ret) {

        fprintf(stderr, "Object %p is not an instance of type %s\n",

                class, typename);

        abort();

    }

    return ret;

}

const char *object_get_typename(Object *obj)

{

    return obj->class->type->name;

}

ObjectClass *object_get_class(Object *obj)

{

    return obj->class;

}

const char *object_class_get_name(ObjectClass *klass)

{

    return klass->type->name;

}

ObjectClass *object_class_by_name(const char *typename)

{

    TypeImpl *type = type_get_by_name(typename);

    if (!type) {

        return NULL;

    }

    type_class_init(type);

    return type->class;

}

typedef struct OCFData

{

    void (*fn)(ObjectClass *klass, void *opaque);

    const char *implements_type;

    bool include_abstract;

    void *opaque;

} OCFData;

static void object_class_foreach_tramp(gpointer key, gpointer value,

                                       gpointer opaque)

{

    OCFData *data = opaque;

    TypeImpl *type = value;

    ObjectClass *k;

    type_class_init(type);

    k = type->class;

    if (!data->include_abstract && type->abstract) {

        return;

    }

    if (data->implements_type && 

        !object_class_dynamic_cast(k, data->implements_type)) {

        return;

    }

    data->fn(k, data->opaque);

}

void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),

                          const char *implements_type, bool include_abstract,

                          void *opaque)

{

    OCFData data = { fn, implements_type, include_abstract, opaque };

    g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);

}

void object_ref(Object *obj)

{

    obj->ref++;

}

void object_unref(Object *obj)

{

    g_assert(obj->ref > 0);

    obj->ref--;

    /* parent always holds a reference to its children */

    if (obj->ref == 0) {

        object_finalize(obj);

    }

}

void object_property_add(Object *obj, const char *name, const char *type,

                         ObjectPropertyAccessor *get,

                         ObjectPropertyAccessor *set,

                         ObjectPropertyRelease *release,

                         void *opaque, Error **errp)

{

    ObjectProperty *prop = g_malloc0(sizeof(*prop));

    prop->name = g_strdup(name);

    prop->type = g_strdup(type);

    prop->get = get;

    prop->set = set;

    prop->release = release;

    prop->opaque = opaque;

    QTAILQ_INSERT_TAIL(&obj->properties, prop, node);

}

static ObjectProperty *object_property_find(Object *obj, const char *name)

{

    ObjectProperty *prop;

    QTAILQ_FOREACH(prop, &obj->properties, node) {

        if (strcmp(prop->name, name) == 0) {

            return prop;

        }

    }

    return NULL;

}

void object_property_del(Object *obj, const char *name, Error **errp)

{

    ObjectProperty *prop = object_property_find(obj, name);

    QTAILQ_REMOVE(&obj->properties, prop, node);

    prop->release(obj, prop->name, prop->opaque);

    g_free(prop->name);

    g_free(prop->type);

    g_free(prop);

}

void object_property_get(Object *obj, Visitor *v, const char *name,

                         Error **errp)

{

    ObjectProperty *prop = object_property_find(obj, name);

    if (prop == NULL) {

        error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);

        return;

    }

    if (!prop->get) {

        error_set(errp, QERR_PERMISSION_DENIED);

    } else {

        prop->get(obj, v, prop->opaque, name, errp);

    }

}

void object_property_set(Object *obj, Visitor *v, const char *name,

                         Error **errp)

{

    ObjectProperty *prop = object_property_find(obj, name);

    if (prop == NULL) {

        error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);

        return;

    }

    if (!prop->set) {

        error_set(errp, QERR_PERMISSION_DENIED);

    } else {

        prop->set(obj, v, prop->opaque, name, errp);

    }

}

void object_property_set_str(Object *obj, const char *value,

                             const char *name, Error **errp)

{

    QString *qstr = qstring_from_str(value);

    object_property_set_qobject(obj, QOBJECT(qstr), name, errp);

    QDECREF(qstr);

}

char *object_property_get_str(Object *obj, const char *name,

                              Error **errp)

{

    QObject *ret = object_property_get_qobject(obj, name, errp);

    QString *qstring;

    char *retval;

    if (!ret) {

        return NULL;

    }

    qstring = qobject_to_qstring(ret);

    if (!qstring) {

        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "string");

        retval = NULL;

    } else {

        retval = g_strdup(qstring_get_str(qstring));

    }

    QDECREF(qstring);

    return retval;

}

void object_property_set_bool(Object *obj, bool value,

                              const char *name, Error **errp)

{

    QBool *qbool = qbool_from_int(value);

    object_property_set_qobject(obj, QOBJECT(qbool), name, errp);

    QDECREF(qbool);

}

bool object_property_get_bool(Object *obj, const char *name,

                              Error **errp)

{

    QObject *ret = object_property_get_qobject(obj, name, errp);

    QBool *qbool;

    bool retval;

    if (!ret) {

        return false;

    }

    qbool = qobject_to_qbool(ret);

    if (!qbool) {

        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "boolean");

        retval = false;

    } else {

        retval = qbool_get_int(qbool);

    }

    QDECREF(qbool);

    return retval;

}

void object_property_set_int(Object *obj, int64_t value,

                             const char *name, Error **errp)

{

    QInt *qint = qint_from_int(value);

    object_property_set_qobject(obj, QOBJECT(qint), name, errp);

    QDECREF(qint);

}

int64_t object_property_get_int(Object *obj, const char *name,

                                Error **errp)

{

    QObject *ret = object_property_get_qobject(obj, name, errp);

    QInt *qint;

    int64_t retval;

    if (!ret) {

        return -1;

    }

    qint = qobject_to_qint(ret);

    if (!qint) {

        error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, "int");

        retval = -1;

    } else {

        retval = qint_get_int(qint);

    }

    QDECREF(qint);

    return retval;

}

const char *object_property_get_type(Object *obj, const char *name, Error **errp)

{

    ObjectProperty *prop = object_property_find(obj, name);

    if (prop == NULL) {

        error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);

        return NULL;

    }

    return prop->type;

}

Object *object_get_root(void)

{

    static Object *root;

    if (!root) {

        root = object_new("container");

    }

    return root;

}

static void object_get_child_property(Object *obj, Visitor *v, void *opaque,

                                      const char *name, Error **errp)

{

    Object *child = opaque;

    gchar *path;

    path = object_get_canonical_path(child);

    visit_type_str(v, &path, name, errp);

    g_free(path);

}

static void object_finalize_child_property(Object *obj, const char *name,

                                           void *opaque)

{

    Object *child = opaque;

    object_unref(child);

}

void object_property_add_child(Object *obj, const char *name,

                               Object *child, Error **errp)

{

    gchar *type;

    type = g_strdup_printf("child<%s>", object_get_typename(OBJECT(child)));

    object_property_add(obj, name, type, object_get_child_property,

                        NULL, object_finalize_child_property, child, errp);

    object_ref(child);

    g_assert(child->parent == NULL);

    child->parent = obj;

    g_free(type);

}

static void object_get_link_property(Object *obj, Visitor *v, void *opaque,

                                     const char *name, Error **errp)

{

    Object **child = opaque;

    gchar *path;

    if (*child) {

        path = object_get_canonical_path(*child);

        visit_type_str(v, &path, name, errp);

        g_free(path);

    } else {

        path = (gchar *)"";

        visit_type_str(v, &path, name, errp);

    }

}

static void object_set_link_property(Object *obj, Visitor *v, void *opaque,

                                     const char *name, Error **errp)

{

    Object **child = opaque;

    bool ambiguous = false;

    const char *type;

    char *path;

    type = object_property_get_type(obj, name, NULL);

    visit_type_str(v, &path, name, errp);

    if (*child) {

        object_unref(*child);

    }

    if (strcmp(path, "") != 0) {

        Object *target;

        target = object_resolve_path(path, &ambiguous);

        if (target) {

            gchar *target_type;

            target_type = g_strdup(&type[5]);

            target_type[strlen(target_type) - 2] = 0;

            if (object_dynamic_cast(target, target_type)) {

                object_ref(target);

                *child = target;

            } else {

                error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, type);

            }

            g_free(target_type);

        } else {

            error_set(errp, QERR_DEVICE_NOT_FOUND, path);

        }

    } else {

        *child = NULL;

    }

    g_free(path);

}

void object_property_add_link(Object *obj, const char *name,

                              const char *type, Object **child,

                              Error **errp)

{

    gchar *full_type;

    full_type = g_strdup_printf("link<%s>", type);

    object_property_add(obj, name, full_type,

                        object_get_link_property,

                        object_set_link_property,

                        NULL, child, errp);

    g_free(full_type);

}

gchar *object_get_canonical_path(Object *obj)

{

    Object *root = object_get_root();

    char *newpath = NULL, *path = NULL;

    while (obj != root) {

        ObjectProperty *prop = NULL;

        g_assert(obj->parent != NULL);

        QTAILQ_FOREACH(prop, &obj->parent->properties, node) {

            if (!strstart(prop->type, "child<", NULL)) {

                continue;

            }

            if (prop->opaque == obj) {

                if (path) {

                    newpath = g_strdup_printf("%s/%s", prop->name, path);

                    g_free(path);

                    path = newpath;

                } else {

                    path = g_strdup(prop->name);

                }

                break;

            }

        }

        g_assert(prop != NULL);

        obj = obj->parent;

    }

    newpath = g_strdup_printf("/%s", path);

    g_free(path);

    return newpath;

}

static Object *object_resolve_abs_path(Object *parent,

                                          gchar **parts,

                                          int index)

{

    ObjectProperty *prop;

    Object *child;

    if (parts[index] == NULL) {

        return parent;

    }

    if (strcmp(parts[index], "") == 0) {

        return object_resolve_abs_path(parent, parts, index + 1);

    }

    prop = object_property_find(parent, parts[index]);

    if (prop == NULL) {

        return NULL;

    }

    child = NULL;

    if (strstart(prop->type, "link<", NULL)) {

        Object **pchild = prop->opaque;

        if (*pchild) {

            child = *pchild;

        }

    } else if (strstart(prop->type, "child<", NULL)) {

        child = prop->opaque;

    }

    if (!child) {

        return NULL;

    }

    return object_resolve_abs_path(child, parts, index + 1);

}

static Object *object_resolve_partial_path(Object *parent,

                                              gchar **parts,

                                              bool *ambiguous)

{

    Object *obj;

    ObjectProperty *prop;

    obj = object_resolve_abs_path(parent, parts, 0);

    QTAILQ_FOREACH(prop, &parent->properties, node) {

        Object *found;

        if (!strstart(prop->type, "child<", NULL)) {

            continue;

        }

        found = object_resolve_partial_path(prop->opaque, parts, ambiguous);

        if (found) {

            if (obj) {

                if (ambiguous) {

                    *ambiguous = true;

                }

                return NULL;

            }

            obj = found;

        }

        if (ambiguous && *ambiguous) {

            return NULL;

        }

    }

    return obj;

}

Object *object_resolve_path(const char *path, bool *ambiguous)

{

    bool partial_path = true;

    Object *obj;

    gchar **parts;

    parts = g_strsplit(path, "/", 0);

    if (parts == NULL || parts[0] == NULL) {

        g_strfreev(parts);

        return object_get_root();

    }

    if (strcmp(parts[0], "") == 0) {

        partial_path = false;

    }

    if (partial_path) {

        if (ambiguous) {

            *ambiguous = false;

        }

        obj = object_resolve_partial_path(object_get_root(), parts, ambiguous);

    } else {

        obj = object_resolve_abs_path(object_get_root(), parts, 1);

    }

    g_strfreev(parts);

    return obj;

}

typedef struct StringProperty

{

    char *(*get)(Object *, Error **);

    void (*set)(Object *, const char *, Error **);

} StringProperty;

static void property_get_str(Object *obj, Visitor *v, void *opaque,

                             const char *name, Error **errp)

{

    StringProperty *prop = opaque;

    char *value;

    value = prop->get(obj, errp);

    if (value) {

        visit_type_str(v, &value, name, errp);

        g_free(value);

    }

}

static void property_set_str(Object *obj, Visitor *v, void *opaque,

                             const char *name, Error **errp)

{

    StringProperty *prop = opaque;

    char *value;

    Error *local_err = NULL;

    visit_type_str(v, &value, name, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        return;

    }

    prop->set(obj, value, errp);

    g_free(value);

}

static void property_release_str(Object *obj, const char *name,

                                 void *opaque)

{

    StringProperty *prop = opaque;

    g_free(prop);

}

void object_property_add_str(Object *obj, const char *name,

                           char *(*get)(Object *, Error **),

                           void (*set)(Object *, const char *, Error **),

                           Error **errp)

{

    StringProperty *prop = g_malloc0(sizeof(*prop));

    prop->get = get;

    prop->set = set;

    object_property_add(obj, name, "string",

                        get ? property_get_str : NULL,

                        set ? property_set_str : NULL,

                        property_release_str,

                        prop, errp);

}