1 files changed, 99 insertions, 32 deletions

diff --git a/qom/object.c b/qom/object.c
index a2a1ffa1b3..f4de619b7b 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1023,10 +1023,23 @@ out:
     g_free(type);
 }
 
+void object_property_allow_set_link(Object *obj, const char *name,
+                                    Object *val, Error **errp)
+{
+    /* Allow the link to be set, always */
+}
+
+typedef struct {
+    Object **child;
+    void (*check)(Object *, const char *, Object *, Error **);
+    ObjectPropertyLinkFlags flags;
+} LinkProperty;
+
 static void object_get_link_property(Object *obj, Visitor *v, void *opaque,
                                      const char *name, Error **errp)
 {
-    Object **child = opaque;
+    LinkProperty *lprop = opaque;
+    Object **child = lprop->child;
     gchar *path;
 
     if (*child) {
@@ -1039,65 +1052,119 @@ static void object_get_link_property(Object *obj, Visitor *v, void *opaque,
     }
 }
 
-static void object_set_link_property(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+/*
+ * object_resolve_link:
+ *
+ * Lookup an object and ensure its type matches the link property type.  This
+ * is similar to object_resolve_path() except type verification against the
+ * link property is performed.
+ *
+ * Returns: The matched object or NULL on path lookup failures.
+ */
+static Object *object_resolve_link(Object *obj, const char *name,
+                                   const char *path, Error **errp)
 {
-    Object **child = opaque;
-    Object *old_target;
-    bool ambiguous = false;
     const char *type;
-    char *path;
     gchar *target_type;
+    bool ambiguous = false;
+    Object *target;
 
+    /* Go from link<FOO> to FOO.  */
     type = object_property_get_type(obj, name, NULL);
+    target_type = g_strndup(&type[5], strlen(type) - 6);
+    target = object_resolve_path_type(path, target_type, &ambiguous);
+
+    if (ambiguous) {
+        error_set(errp, QERR_AMBIGUOUS_PATH, path);
+    } else if (!target) {
+        target = object_resolve_path(path, &ambiguous);
+        if (target || ambiguous) {
+            error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, target_type);
+        } else {
+            error_set(errp, QERR_DEVICE_NOT_FOUND, path);
+        }
+        target = NULL;
+    }
+    g_free(target_type);
 
-    visit_type_str(v, &path, name, errp);
-
-    old_target = *child;
-    *child = NULL;
+    return target;
+}
 
-    if (strcmp(path, "") != 0) {
-        Object *target;
+static void object_set_link_property(Object *obj, Visitor *v, void *opaque,
+                                     const char *name, Error **errp)
+{
+    Error *local_err = NULL;
+    LinkProperty *prop = opaque;
+    Object **child = prop->child;
+    Object *old_target = *child;
+    Object *new_target = NULL;
+    char *path = NULL;
 
-        /* Go from link<FOO> to FOO.  */
-        target_type = g_strndup(&type[5], strlen(type) - 6);
-        target = object_resolve_path_type(path, target_type, &ambiguous);
+    visit_type_str(v, &path, name, &local_err);
 
-        if (ambiguous) {
-            error_set(errp, QERR_AMBIGUOUS_PATH, path);
-        } else if (target) {
-            object_ref(target);
-            *child = target;
-        } else {
-            target = object_resolve_path(path, &ambiguous);
-            if (target || ambiguous) {
-                error_set(errp, QERR_INVALID_PARAMETER_TYPE, name, target_type);
-            } else {
-                error_set(errp, QERR_DEVICE_NOT_FOUND, path);
-            }
-        }
-        g_free(target_type);
+    if (!local_err && strcmp(path, "") != 0) {
+        new_target = object_resolve_link(obj, name, path, &local_err);
     }
 
     g_free(path);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
 
+    prop->check(obj, name, new_target, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    if (new_target) {
+        object_ref(new_target);
+    }
+    *child = new_target;
     if (old_target != NULL) {
         object_unref(old_target);
     }
 }
 
+static void object_release_link_property(Object *obj, const char *name,
+                                         void *opaque)
+{
+    LinkProperty *prop = opaque;
+
+    if ((prop->flags & OBJ_PROP_LINK_UNREF_ON_RELEASE) && *prop->child) {
+        object_unref(*prop->child);
+    }
+    g_free(prop);
+}
+
 void object_property_add_link(Object *obj, const char *name,
                               const char *type, Object **child,
+                              void (*check)(Object *, const char *,
+                                            Object *, Error **),
+                              ObjectPropertyLinkFlags flags,
                               Error **errp)
 {
+    Error *local_err = NULL;
+    LinkProperty *prop = g_malloc(sizeof(*prop));
     gchar *full_type;
 
+    prop->child = child;
+    prop->check = check;
+    prop->flags = flags;
+
     full_type = g_strdup_printf("link<%s>", type);
 
     object_property_add(obj, name, full_type,
                         object_get_link_property,
-                        object_set_link_property,
-                        NULL, child, errp);
+                        check ? object_set_link_property : NULL,
+                        object_release_link_property,
+                        prop,
+                        &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        g_free(prop);
+    }
 
     g_free(full_type);
 }