From eddfb13c2ce8cda563604bfbdb0ca37ff7fb7334 Mon Sep 17 00:00:00 2001
From: "Daniel P. Berrange" <berrange@redhat.com>
Date: Wed, 21 Feb 2018 21:03:44 -0500
Subject: [PATCH] qom: Change object property iterator API contract

Currently the ObjectProperty iterator API works as follows:

ObjectPropertyIterator *iter;

iter = object_property_iter_init(obj);
while ((prop = object_property_iter_next(iter))) {
...
}
object_property_iter_free(iter);

This has the benefit that the ObjectPropertyIterator struct
can be opaque, but has the downside that callers need to
explicitly call a free function. It is also not in keeping
with iterator style used elsewhere in QEMU/GLib2.

This patch changes the API to use stack allocation instead:

ObjectPropertyIterator iter;

object_property_iter_init(&iter, obj);
while ((prop = object_property_iter_next(&iter))) {
...
}

Backports commit 7746abd8e9ee9db20c0b0fdb19504f163ba3cbea from qemu
---
 qemu/include/qom/object.h | 30 ++++++++++++++----------------
 qemu/qom/object.c         | 23 ++++-------------------
 2 files changed, 18 insertions(+), 35 deletions(-)

diff --git a/qemu/include/qom/object.h b/qemu/include/qom/object.h
index 352f2f2f..5d837eb7 100644
--- a/qemu/include/qom/object.h
+++ b/qemu/include/qom/object.h
@@ -827,7 +827,10 @@ ObjectProperty *object_property_find(struct uc_struct *uc, Object *obj,
 ObjectProperty *object_class_property_find(struct uc_struct *uc, ObjectClass *klass,
                                            const char *name, Error **errp);
 
-typedef struct ObjectPropertyIterator ObjectPropertyIterator;
+typedef struct ObjectPropertyIterator {
+    ObjectClass *nextclass;
+    GHashTableIter iter;
+} ObjectPropertyIterator;
 
 /**
  * object_property_iter_init:
@@ -845,32 +848,27 @@ typedef struct ObjectPropertyIterator ObjectPropertyIterator;
  *   <title>Using object property iterators</title>
  *   <programlisting>
  *   ObjectProperty *prop;
- *   ObjectPropertyIterator *iter;
+ *   ObjectPropertyIterator iter;
  *
- *   iter = object_property_iter_init(obj);
- *   while ((prop = object_property_iter_next(iter))) {
+ *   object_property_iter_init(&iter, obj);
+ *   while ((prop = object_property_iter_next(&iter))) {
  *     ... do something with prop ...
  *   }
- *   object_property_iter_free(iter);
  *   </programlisting>
  * </example>
- *
- * Returns: the new iterator
  */
-ObjectPropertyIterator *object_property_iter_init(Object *obj);
-
-/**
- * object_property_iter_free:
- * @iter: the iterator instance
- *
- * Releases any resources associated with the iterator.
- */
-void object_property_iter_free(ObjectPropertyIterator *iter);
+void object_property_iter_init(ObjectPropertyIterator *iter,
+                               Object *obj);
 
 /**
  * object_property_iter_next:
  * @iter: the iterator instance
  *
+ * Return the next available property. If no further properties
+ * are available, a %NULL value will be returned and the @iter
+ * pointer should not be used again after this point without
+ * re-initializing it.
+ *
  * Returns: the next property, or %NULL when all properties
  * have been traversed.
  */
diff --git a/qemu/qom/object.c b/qemu/qom/object.c
index 18075868..ccb3f964 100644
--- a/qemu/qom/object.c
+++ b/qemu/qom/object.c
@@ -66,11 +66,6 @@ struct TypeImpl
     InterfaceImpl interfaces[MAX_INTERFACES];
 };
 
-struct ObjectPropertyIterator {
-    ObjectClass *nextclass;
-    GHashTableIter iter;
-};
-
 static GHashTable *type_table_get(struct uc_struct *uc)
 {
     if (uc->type_table == NULL) {
@@ -80,7 +75,6 @@ static GHashTable *type_table_get(struct uc_struct *uc)
     return uc->type_table;
 }
 
-
 static void type_table_add(struct uc_struct *uc, TypeImpl *ti)
 {
     assert(!uc->enumerating_types);
@@ -883,20 +877,11 @@ ObjectProperty *object_property_find(struct uc_struct *uc, Object *obj,
     return NULL;
 }
 
-ObjectPropertyIterator *object_property_iter_init(Object *obj)
+void object_property_iter_init(ObjectPropertyIterator *iter,
+                               Object *obj)
 {
-    ObjectPropertyIterator *ret = g_new0(ObjectPropertyIterator, 1);
-    g_hash_table_iter_init(&ret->iter, obj->properties);
-    ret->nextclass = object_get_class(obj);
-    return ret;
-}
-
-void object_property_iter_free(ObjectPropertyIterator *iter)
-{
-    if (!iter) {
-        return;
-    }
-    g_free(iter);
+    g_hash_table_iter_init(&iter->iter, obj->properties);
+    iter->nextclass = object_get_class(obj);
 }
 
 ObjectProperty *object_property_iter_next(struct uc_struct *uc, ObjectPropertyIterator *iter)