qom: centralize module-loading functionality

Put together the common code of object_initialize() and
module_object_class_by_name() into a function that supports
Error **.  Rename the existing function type_get_by_name() to
clarify that it will only look at defined types; this is often
okay within object.c to look at the parents, but not outside it.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qom/object.c

@@ -195,7 +195,7 @@ void type_register_static_array(const TypeInfo *infos, int nr_infos)
     }
 }
 
-static TypeImpl *type_get_by_name(const char *name)
+static TypeImpl *type_get_by_name_noload(const char *name)
 {
     if (name == NULL) {
         return NULL;
@@ -204,10 +204,32 @@ static TypeImpl *type_get_by_name(const char *name)
     return type_table_lookup(name);
 }
 
+static TypeImpl *type_get_or_load_by_name(const char *name, Error **errp)
+{
+    TypeImpl *type = type_get_by_name_noload(name);
+
+#ifdef CONFIG_MODULES
+    if (!type) {
+        int rv = module_load_qom(name, errp);
+        if (rv > 0) {
+            type = type_get_by_name_noload(name);
+        } else {
+            error_prepend(errp, "could not load a module for type '%s'", name);
+            return NULL;
+        }
+    }
+#endif
+    if (!type) {
+        error_setg(errp, "unknown type '%s'", name);
+    }
+
+    return type;
+}
+
 static TypeImpl *type_get_parent(TypeImpl *type)
 {
     if (!type->parent_type && type->parent) {
-        type->parent_type = type_get_by_name(type->parent);
+        type->parent_type = type_get_by_name_noload(type->parent);
         if (!type->parent_type) {
             fprintf(stderr, "Type '%s' is missing its parent '%s'\n",
                     type->name, type->parent);
@@ -363,7 +385,7 @@ static void type_initialize(TypeImpl *ti)
         }
 
         for (i = 0; i < ti->num_interfaces; i++) {
-            TypeImpl *t = type_get_by_name(ti->interfaces[i].typename);
+            TypeImpl *t = type_get_by_name_noload(ti->interfaces[i].typename);
             if (!t) {
                 error_report("missing interface '%s' for object '%s'",
                              ti->interfaces[i].typename, parent->name);
@@ -557,23 +579,7 @@ static void object_initialize_with_type(Object *obj, size_t size, TypeImpl *type
 
 void object_initialize(void *data, size_t size, const char *typename)
 {
-    TypeImpl *type = type_get_by_name(typename);
-
-#ifdef CONFIG_MODULES
-    if (!type) {
-        int rv = module_load_qom(typename, &error_fatal);
-        if (rv > 0) {
-            type = type_get_by_name(typename);
-        } else {
-            error_report("missing object type '%s'", typename);
-            exit(1);
-        }
-    }
-#endif
-    if (!type) {
-        error_report("missing object type '%s'", typename);
-        abort();
-    }
+    TypeImpl *type = type_get_or_load_by_name(typename, &error_fatal);
 
     object_initialize_with_type(data, size, type);
 }
@@ -784,7 +790,7 @@ Object *object_new_with_class(ObjectClass *klass)
 
 Object *object_new(const char *typename)
 {
-    TypeImpl *ti = type_get_by_name(typename);
+    TypeImpl *ti = type_get_by_name_noload(typename);
 
     return object_new_with_type(ti);
 }
@@ -957,7 +963,7 @@ ObjectClass *object_class_dynamic_cast(ObjectClass *class,
         return class;
     }
 
-    target_type = type_get_by_name(typename);
+    target_type = type_get_by_name_noload(typename);
     if (!target_type) {
         /* target class type unknown, so fail the cast */
         return NULL;
@@ -1055,7 +1061,7 @@ const char *object_class_get_name(ObjectClass *klass)
 
 ObjectClass *object_class_by_name(const char *typename)
 {
-    TypeImpl *type = type_get_by_name(typename);
+    TypeImpl *type = type_get_by_name_noload(typename);
 
     if (!type) {
         return NULL;
@@ -1068,21 +1074,15 @@ ObjectClass *object_class_by_name(const char *typename)
 
 ObjectClass *module_object_class_by_name(const char *typename)
 {
-    ObjectClass *oc;
+    TypeImpl *type = type_get_or_load_by_name(typename, NULL);
 
-    oc = object_class_by_name(typename);
-#ifdef CONFIG_MODULES
-    if (!oc) {
-        Error *local_err = NULL;
-        int rv = module_load_qom(typename, &local_err);
-        if (rv > 0) {
-            oc = object_class_by_name(typename);
-        } else if (rv < 0) {
-            error_report_err(local_err);
-        }
+    if (!type) {
+        return NULL;
     }
-#endif
-    return oc;
+
+    type_initialize(type);
+
+    return type->class;
 }
 
 ObjectClass *object_class_get_parent(ObjectClass *class)