Re: [Qemu-devel] [patch 2/3] add object_property_add_alias

[Paolo Bonzini]

Il 04/06/2014 19:52, mtosa...@redhat.com ha scritto:
Allowing addition of a link without keeping pointer-to-pointer.
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>

---
 include/qom/object.h |   13 +++++++++
 qom/object.c         |   73 +++++++++++++++++++++++++++++++++++++++++----------
 2 files changed, 72 insertions(+), 14 deletions(-)

Index: qemu/include/qom/object.h
===================================================================
--- qemu.orig/include/qom/object.h      2014-06-02 23:12:51.875693325 -0300
+++ qemu/include/qom/object.h   2014-06-02 23:14:13.045432426 -0300
@@ -1073,6 +1073,19 @@
 } ObjectPropertyLinkFlags;

 /**
+ * object_property_add_alias:
+ * @obj: the object to add a property to
+ * @name: the name of the property
+ * @alias: the alias object
+ * @errp: if an error occurs, a pointer to an area to store the area
+ *
+ * Add a link under obj, named name, pointing to alias.
+ *
+ */
+void object_property_add_alias(Object *obj, const char *name,
+                               Object *alias, Error **errp);
+
+/**
  * object_property_allow_set_link:
  *
  * The default implementation of the object_property_add_link() check()
Index: qemu/qom/object.c
===================================================================
--- qemu.orig/qom/object.c      2014-06-02 23:12:51.875693325 -0300
+++ qemu/qom/object.c   2014-06-02 23:14:13.046432423 -0300
@@ -1023,27 +1023,71 @@
     g_free(type);
 }

+typedef struct {
+    Object *child;
+    Object **childp;

These field names are ugly... not your fault, but perhaps

    Object **linkp;
    Object *alias_dest;

would be better.  It would also avoid the mistake below:

@@ -1096,7 +1140,7 @@
 {
     Error *local_err = NULL;
     LinkProperty *prop = opaque;
-    Object **child = prop->child;
+    Object **child = prop->childp;
     Object *old_target = *child;
     Object *new_target = NULL;
     char *path = NULL;

This is object_set_link_property.  It writes *child but not prop->child, 
and subsequent calls to object_get_link_property incorrect.

However, since a similar need arose recently in one of Peter 
Crosthwaite's patches, let's add a generic resolve mechanism.  I'll post 
a short series in a second, as soon as I finish testing it.

Paolo

@@ -1133,8 +1177,8 @@
 {
     LinkProperty *prop = opaque;

-    if ((prop->flags & OBJ_PROP_LINK_UNREF_ON_RELEASE) && *prop->child) {
-        object_unref(*prop->child);
+    if ((prop->flags & OBJ_PROP_LINK_UNREF_ON_RELEASE) && prop->child) {
+        object_unref(prop->child);
     }
     g_free(prop);
 }
@@ -1150,7 +1194,8 @@
     LinkProperty *prop = g_malloc(sizeof(*prop));
     gchar *full_type;

-    prop->child = child;
+    prop->childp = child;
+    prop->child = *child;
     prop->check = check;
     prop->flags = flags;

@@ -1227,7 +1272,7 @@

     if (object_property_is_link(prop)) {
         LinkProperty *lprop = prop->opaque;
-        return *lprop->child;
+        return lprop->child;
     } else if (object_property_is_child(prop)) {
         return prop->opaque;
     } else {