]> git.proxmox.com Git - mirror_qemu.git/blobdiff - qom/object.c
qbus: Make child devices links
[mirror_qemu.git] / qom / object.c
index ef37e080d4e21725588edfe540e764b1357a001c..27cc651a91c21a8cbf8002b5d3cf63c8a3371eaf 100644 (file)
 
 #include "qemu/object.h"
 #include "qemu-common.h"
+#include "qapi/qapi-visit-core.h"
+#include "qapi/string-input-visitor.h"
+#include "qapi/string-output-visitor.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
 
@@ -34,6 +45,7 @@ struct TypeImpl
     size_t instance_size;
 
     void (*class_init)(ObjectClass *klass, void *data);
+    void (*class_base_init)(ObjectClass *klass, void *data);
     void (*class_finalize)(ObjectClass *klass, void *data);
 
     void *class_data;
@@ -60,6 +72,8 @@ typedef struct Interface
 
 #define INTERFACE(obj) OBJECT_CHECK(Interface, obj, TYPE_INTERFACE)
 
+static Type type_interface;
+
 static GHashTable *type_table_get(void)
 {
     static GHashTable *type_table;
@@ -81,12 +95,17 @@ static TypeImpl *type_table_lookup(const char *name)
     return g_hash_table_lookup(type_table_get(), name);
 }
 
-TypeImpl *type_register(const TypeInfo *info)
+static TypeImpl *type_register_internal(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);
 
@@ -94,6 +113,7 @@ TypeImpl *type_register(const TypeInfo *info)
     ti->instance_size = info->instance_size;
 
     ti->class_init = info->class_init;
+    ti->class_base_init = info->class_base_init;
     ti->class_finalize = info->class_finalize;
     ti->class_data = info->class_data;
 
@@ -117,6 +137,12 @@ TypeImpl *type_register(const TypeInfo *info)
     return ti;
 }
 
+TypeImpl *type_register(const TypeInfo *info)
+{
+    assert(info->parent);
+    return type_register_internal(info);
+}
+
 TypeImpl *type_register_static(const TypeInfo *info)
 {
     return type_register(info);
@@ -159,6 +185,19 @@ static size_t type_class_get_size(TypeImpl *ti)
     return sizeof(ObjectClass);
 }
 
+static size_t type_object_get_size(TypeImpl *ti)
+{
+    if (ti->instance_size) {
+        return ti->instance_size;
+    }
+
+    if (type_has_parent(ti)) {
+        return type_object_get_size(type_get_parent(ti));
+    }
+
+    return 0;
+}
+
 static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)
 {
     TypeInfo info = {
@@ -171,13 +210,13 @@ static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)
     char *name = g_strdup_printf("<%s::%s>", ti->name, iface->parent);
 
     info.name = name;
-    iface->type = type_register(&info);
+    iface->type = type_register_internal(&info);
     g_free(name);
 }
 
-static void type_class_init(TypeImpl *ti)
+static void type_initialize(TypeImpl *ti)
 {
-    size_t class_size = sizeof(ObjectClass);
+    TypeImpl *parent;
     int i;
 
     if (ti->class) {
@@ -185,24 +224,26 @@ static void type_class_init(TypeImpl *ti)
     }
 
     ti->class_size = type_class_get_size(ti);
+    ti->instance_size = type_object_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);
+    parent = type_get_parent(ti);
+    if (parent) {
+        type_initialize(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));
+        memcpy(ti->class, parent->class, parent->class_size);
     }
 
-    memset((void *)ti->class + class_size, 0, ti->class_size - class_size);
+    ti->class->type = ti;
+
+    while (parent) {
+        if (parent->class_base_init) {
+            parent->class_base_init(ti->class, ti->class_data);
+        }
+        parent = type_get_parent(parent);
+    }
 
     for (i = 0; i < ti->num_interfaces; i++) {
         type_class_interface_init(ti, &ti->interfaces[i]);
@@ -246,13 +287,14 @@ void object_initialize_with_type(void *data, TypeImpl *type)
     Object *obj = data;
 
     g_assert(type != NULL);
-    g_assert(type->instance_size >= sizeof(ObjectClass));
+    type_initialize(type);
 
-    type_class_init(type);
+    g_assert(type->instance_size >= sizeof(Object));
     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);
 }
 
@@ -263,6 +305,52 @@ void object_initialize(void *data, const char *typename)
     object_initialize_with_type(data, type);
 }
 
+static inline bool object_property_is_child(ObjectProperty *prop)
+{
+    return strstart(prop->type, "child<", NULL);
+}
+
+static inline bool object_property_is_link(ObjectProperty *prop)
+{
+    return strstart(prop->type, "link<", NULL);
+}
+
+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 (object_property_is_child(prop) && prop->opaque == child) {
+            object_property_del(obj, prop->name, errp);
+            break;
+        }
+    }
+}
+
+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) {
@@ -278,6 +366,8 @@ static void object_deinit(Object *obj, TypeImpl *type)
     if (type_has_parent(type)) {
         object_deinit(obj, type_get_parent(type));
     }
+
+    object_unparent(obj);
 }
 
 void object_finalize(void *data)
@@ -286,6 +376,9 @@ void object_finalize(void *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)
@@ -293,9 +386,11 @@ Object *object_new_with_type(Type type)
     Object *obj;
 
     g_assert(type != NULL);
+    type_initialize(type);
 
     obj = g_malloc(type->instance_size);
     object_initialize_with_type(obj, type);
+    object_ref(obj);
 
     return obj;
 }
@@ -309,15 +404,14 @@ Object *object_new(const char *typename)
 
 void object_delete(Object *obj)
 {
-    object_finalize(obj);
+    object_unref(obj);
+    g_assert(obj->ref == 0);
     g_free(obj);
 }
 
-static bool object_is_type(Object *obj, const char *typename)
+static bool type_is_ancestor(TypeImpl *type, TypeImpl *target_type)
 {
-    TypeImpl *target_type = type_get_by_name(typename);
-    TypeImpl *type = obj->class->type;
-    GSList *i;
+    assert(target_type);
 
     /* Check if typename is a direct ancestor of type */
     while (type) {
@@ -328,24 +422,45 @@ static bool object_is_type(Object *obj, const char *typename)
         type = type_get_parent(type);
     }
 
-    /* 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), typename)) {
-            return true;
-        }
-    }
-
     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 */
-    if (object_is_type(obj, typename)) {
+    /* 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;
     }
 
@@ -353,38 +468,15 @@ Object *object_dynamic_cast(Object *obj, const char *typename)
     for (i = obj->interfaces; i; i = i->next) {
         Interface *iface = i->data;
 
-        if (object_is_type(OBJECT(iface), typename)) {
+        if (object_is_type(OBJECT(iface), target_type)) {
             return OBJECT(iface);
         }
     }
 
-    /* Check if obj is an interface and its containing object is a direct
-     * ancestor of typename */
-    if (object_is_type(obj, TYPE_INTERFACE)) {
-        Interface *iface = INTERFACE(obj);
-
-        if (object_is_type(iface->obj, typename)) {
-            return iface->obj;
-        }
-    }
-
     return NULL;
 }
 
 
-static void register_interface(void)
-{
-    static TypeInfo interface_info = {
-        .name = TYPE_INTERFACE,
-        .instance_size = sizeof(Interface),
-        .abstract = true,
-    };
-
-    type_register_static(&interface_info);
-}
-
-device_init(register_interface);
-
 Object *object_dynamic_cast_assert(Object *obj, const char *typename)
 {
     Object *inst;
@@ -454,7 +546,20 @@ ObjectClass *object_class_by_name(const char *typename)
         return NULL;
     }
 
-    type_class_init(type);
+    type_initialize(type);
+
+    return type->class;
+}
+
+ObjectClass *object_class_get_parent(ObjectClass *class)
+{
+    TypeImpl *type = type_get_parent(class->type);
+
+    if (!type) {
+        return NULL;
+    }
+
+    type_initialize(type);
 
     return type->class;
 }
@@ -462,6 +567,8 @@ ObjectClass *object_class_by_name(const char *typename)
 typedef struct OCFData
 {
     void (*fn)(ObjectClass *klass, void *opaque);
+    const char *implements_type;
+    bool include_abstract;
     void *opaque;
 } OCFData;
 
@@ -470,16 +577,694 @@ static void object_class_foreach_tramp(gpointer key, gpointer value,
 {
     OCFData *data = opaque;
     TypeImpl *type = value;
+    ObjectClass *k;
+
+    type_initialize(type);
+    k = type->class;
+
+    if (!data->include_abstract && type->abstract) {
+        return;
+    }
 
-    type_class_init(type);
+    if (data->implements_type && 
+        !object_class_dynamic_cast(k, data->implements_type)) {
+        return;
+    }
 
-    data->fn(value, type->class);
+    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, opaque };
+    OCFData data = { fn, implements_type, include_abstract, opaque };
 
     g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);
 }
+
+int object_child_foreach(Object *obj, int (*fn)(Object *child, void *opaque),
+                         void *opaque)
+{
+    ObjectProperty *prop;
+    int ret = 0;
+
+    QTAILQ_FOREACH(prop, &obj->properties, node) {
+        if (object_property_is_child(prop)) {
+            ret = fn(prop->opaque, opaque);
+            if (ret != 0) {
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+static void object_class_get_list_tramp(ObjectClass *klass, void *opaque)
+{
+    GSList **list = opaque;
+
+    *list = g_slist_prepend(*list, klass);
+}
+
+GSList *object_class_get_list(const char *implements_type,
+                              bool include_abstract)
+{
+    GSList *list = NULL;
+
+    object_class_foreach(object_class_get_list_tramp,
+                         implements_type, include_abstract, &list);
+    return list;
+}
+
+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);
+
+    if (prop == NULL) {
+        error_set(errp, QERR_PROPERTY_NOT_FOUND, "", name);
+        return;
+    }
+
+    if (prop->release) {
+        prop->release(obj, name, prop->opaque);
+    }
+
+    QTAILQ_REMOVE(&obj->properties, prop, node);
+
+    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_link(Object *obj, Object *value,
+                              const char *name, Error **errp)
+{
+    object_property_set_str(obj, object_get_canonical_path(value),
+                            name, errp);
+}
+
+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)
+{
+    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;
+}
+
+void object_property_parse(Object *obj, const char *string,
+                           const char *name, Error **errp)
+{
+    StringInputVisitor *mi;
+    mi = string_input_visitor_new(string);
+    object_property_set(obj, string_input_get_visitor(mi), name, errp);
+
+    string_input_visitor_cleanup(mi);
+}
+
+char *object_property_print(Object *obj, const char *name,
+                            Error **errp)
+{
+    StringOutputVisitor *mo;
+    char *string;
+
+    mo = string_output_visitor_new();
+    object_property_get(obj, string_output_get_visitor(mo), name, errp);
+    string = string_output_get_string(mo);
+    string_output_visitor_cleanup(mo);
+    return string;
+}
+
+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;
+
+    /* Registering an interface object in the composition tree will mightily
+     * confuse object_get_canonical_path (which, on the other hand, knows how
+     * to get the canonical path of an interface object).
+     */
+    assert(!object_is_type(obj, type_interface));
+
+    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;
+    Object *old_target;
+    bool ambiguous = false;
+    const char *type;
+    char *path;
+    gchar *target_type;
+
+    type = object_property_get_type(obj, name, NULL);
+
+    visit_type_str(v, &path, name, errp);
+
+    old_target = *child;
+    *child = NULL;
+
+    if (strcmp(path, "") != 0) {
+        Object *target;
+
+        /* Go from link<FOO> to FOO.  */
+        target_type = g_strndup(&type[5], strlen(type) - 6);
+        target = object_resolve_path_type(path, target_type, &ambiguous);
+
+        if (ambiguous) {
+            error_set(errp, QERR_AMBIGUOUS_PATH, path);
+        } else if (target) {
+            object_ref(target);
+            *child = target;
+        } else {
+            target = object_resolve_path(path, &ambiguous);
+            if (target || ambiguous) {
+                error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, target_type);
+            } else {
+                error_set(errp, QERR_DEVICE_NOT_FOUND, path);
+            }
+        }
+        g_free(target_type);
+    }
+
+    g_free(path);
+
+    if (old_target != NULL) {
+        object_unref(old_target);
+    }
+}
+
+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;
+
+    if (object_is_type(obj, type_interface)) {
+        obj = INTERFACE(obj)->obj;
+    }
+
+    while (obj != root) {
+        ObjectProperty *prop = NULL;
+
+        g_assert(obj->parent != NULL);
+
+        QTAILQ_FOREACH(prop, &obj->parent->properties, node) {
+            if (!object_property_is_child(prop)) {
+                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;
+}
+
+Object *object_resolve_path_component(Object *parent, gchar *part)
+{
+    ObjectProperty *prop = object_property_find(parent, part);
+    if (prop == NULL) {
+        return NULL;
+    }
+
+    if (object_property_is_link(prop)) {
+        return *(Object **)prop->opaque;
+    } else if (object_property_is_child(prop)) {
+        return prop->opaque;
+    } else {
+        return NULL;
+    }
+}
+
+static Object *object_resolve_abs_path(Object *parent,
+                                          gchar **parts,
+                                          const char *typename,
+                                          int index)
+{
+    Object *child;
+
+    if (parts[index] == NULL) {
+        return object_dynamic_cast(parent, typename);
+    }
+
+    if (strcmp(parts[index], "") == 0) {
+        return object_resolve_abs_path(parent, parts, typename, index + 1);
+    }
+
+    child = object_resolve_path_component(parent, parts[index]);
+    if (!child) {
+        return NULL;
+    }
+
+    return object_resolve_abs_path(child, parts, typename, index + 1);
+}
+
+static Object *object_resolve_partial_path(Object *parent,
+                                              gchar **parts,
+                                              const char *typename,
+                                              bool *ambiguous)
+{
+    Object *obj;
+    ObjectProperty *prop;
+
+    obj = object_resolve_abs_path(parent, parts, typename, 0);
+
+    QTAILQ_FOREACH(prop, &parent->properties, node) {
+        Object *found;
+
+        if (!object_property_is_child(prop)) {
+            continue;
+        }
+
+        found = object_resolve_partial_path(prop->opaque, parts,
+                                            typename, ambiguous);
+        if (found) {
+            if (obj) {
+                if (ambiguous) {
+                    *ambiguous = true;
+                }
+                return NULL;
+            }
+            obj = found;
+        }
+
+        if (ambiguous && *ambiguous) {
+            return NULL;
+        }
+    }
+
+    return obj;
+}
+
+Object *object_resolve_path_type(const char *path, const char *typename,
+                                 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,
+                                          typename, ambiguous);
+    } else {
+        obj = object_resolve_abs_path(object_get_root(), parts, typename, 1);
+    }
+
+    g_strfreev(parts);
+
+    return obj;
+}
+
+Object *object_resolve_path(const char *path, bool *ambiguous)
+{
+    return object_resolve_path_type(path, TYPE_OBJECT, ambiguous);
+}
+
+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);
+}
+
+static char *qdev_get_type(Object *obj, Error **errp)
+{
+    return g_strdup(object_get_typename(obj));
+}
+
+static void object_instance_init(Object *obj)
+{
+    object_property_add_str(obj, "type", qdev_get_type, NULL, NULL);
+}
+
+static void register_types(void)
+{
+    static TypeInfo interface_info = {
+        .name = TYPE_INTERFACE,
+        .instance_size = sizeof(Interface),
+        .abstract = true,
+    };
+
+    static TypeInfo object_info = {
+        .name = TYPE_OBJECT,
+        .instance_size = sizeof(Object),
+        .instance_init = object_instance_init,
+        .abstract = true,
+    };
+
+    type_interface = type_register_internal(&interface_info);
+    type_register_internal(&object_info);
+}
+
+type_init(register_types)