qemu find_default_machine

MachineClass *find_default_machine(void)
{
    GSList *el, *machines = object_class_get_list(TYPE_MACHINE, false);
    MachineClass *mc = NULL;

    for (el = machines; el; el = el->next) {
        MachineClass *temp = el->data;

        if (temp->is_default) {
            mc = temp;
            break;
        }
    }

    g_slist_free(machines);
    return mc;
}

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_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 };

    enumerating_types = true;
    g_hash_table_foreach(type_table_get(), object_class_foreach_tramp, &data);
    enumerating_types = false;
}

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;
}

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_initialize(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);
}

static void type_initialize(TypeImpl *ti)
{
    TypeImpl *parent;

    if (ti->class) {
        return;
    }

    ti->class_size = type_class_get_size(ti);
    ti->instance_size = type_object_get_size(ti);

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

    parent = type_get_parent(ti);
    if (parent) {
        type_initialize(parent);
        GSList *e;
        int i;

        g_assert_cmpint(parent->class_size, <=, ti->class_size);
        memcpy(ti->class, parent->class, parent->class_size);
        ti->class->interfaces = NULL;

        for (e = parent->class->interfaces; e; e = e->next) {
            InterfaceClass *iface = e->data;
            ObjectClass *klass = OBJECT_CLASS(iface);

            type_initialize_interface(ti, iface->interface_type, klass->type);
        }

        for (i = 0; i < ti->num_interfaces; i++) {
            TypeImpl *t = type_get_by_name(ti->interfaces[i].typename);
            for (e = ti->class->interfaces; e; e = e->next) {
                TypeImpl *target_type = OBJECT_CLASS(e->data)->type;

                if (type_is_ancestor(target_type, t)) {
                    break;
                }
            }

            if (e) {
                continue;
            }

            type_initialize_interface(ti, t, t);
        }
    }

    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);
    }

    if (ti->class_init) {
        ti->class_init(ti->class, ti->class_data);
    }
}

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;
}

ObjectClass *object_class_dynamic_cast(ObjectClass *class,
                                       const char *typename)
{
    ObjectClass *ret = NULL;
    TypeImpl *target_type;
    TypeImpl *type;

    if (!class) {
        return NULL;
    }

    /* A simple fast path that can trigger a lot for leaf classes.  */
    type = class->type;
    if (type->name == typename) {
        return class;
    }

    target_type = type_get_by_name(typename);
    if (!target_type) {
        /* target class type unknown, so fail the cast */
        return NULL;
    }

    if (type->class->interfaces &&
            type_is_ancestor(target_type, type_interface)) {
        int found = 0;
        GSList *i;

        for (i = class->interfaces; i; i = i->next) {
            ObjectClass *target_class = i->data;

            if (type_is_ancestor(target_class->type, target_type)) {
                ret = target_class;
                found++;
            }
         }

        /* The match was ambiguous, don't allow a cast */
        if (found > 1) {
            ret = NULL;
        }
    } else if (type_is_ancestor(type, target_type)) {
        ret = class;
    }

    return ret;
}