object: qom module support

Little helper function to load modules on demand.  In most cases adding
module loading support for devices and other objects is just
s/object_class_by_name/module_object_class_by_name/ in the right spot.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20200624131045.14512-3-kraxel@redhat.com

2 files changed, 26 insertions, 0 deletions

diff --git a/include/qom/object.h b/include/qom/object.h
index 94a61ccc3f..51f188137f 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -994,6 +994,18 @@ bool object_class_is_abstract(ObjectClass *klass);
  */
 ObjectClass *object_class_by_name(const char *typename);
 
+/**
+ * module_object_class_by_name:
+ * @typename: The QOM typename to obtain the class for.
+ *
+ * For objects which might be provided by a module.  Behaves like
+ * object_class_by_name, but additionally tries to load the module
+ * needed in case the class is not available.
+ *
+ * Returns: The class for @typename or %NULL if not found.
+ */
+ObjectClass *module_object_class_by_name(const char *typename);
+
 void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),
                           const char *implements_type, bool include_abstract,
                           void *opaque);
diff --git a/qom/object.c b/qom/object.c
index 6ece96bc2b..34daaf1280 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -985,6 +985,20 @@ ObjectClass *object_class_by_name(const char *typename)
     return type->class;
 }
 
+ObjectClass *module_object_class_by_name(const char *typename)
+{
+    ObjectClass *oc;
+
+    oc = object_class_by_name(typename);
+#ifdef CONFIG_MODULES
+    if (!oc) {
+        module_load_qom_one(typename);
+        oc = object_class_by_name(typename);
+    }
+#endif
+    return oc;
+}
+
 ObjectClass *object_class_get_parent(ObjectClass *class)
 {
     TypeImpl *type = type_get_parent(class->type);