qom: Add object_class_get_parent()

This simple bit of functionality was missing and we'll need it soon,
so add it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
[AF: Document possible NULL return value]
Signed-off-by: Andreas Färber <afaerber@suse.de>

include/qemu/object.h

@@ -547,6 +547,14 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass *klass,
 ObjectClass *object_class_dynamic_cast(ObjectClass *klass,
                                        const char *typename);
 
+/**
+ * object_class_get_parent:
+ * @klass: The class to obtain the parent for.
+ *
+ * Returns: The parent for @klass or %NULL if none.
+ */
+ObjectClass *object_class_get_parent(ObjectClass *klass);
+
 /**
  * object_class_get_name:
  * @klass: The class to obtain the QOM typename for.

qom/object.c

@@ -545,6 +545,19 @@ ObjectClass *object_class_by_name(const char *typename)
     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;
+}
+
 typedef struct OCFData
 {
     void (*fn)(ObjectClass *klass, void *opaque);