qom: add child properties (composition) (v3)

Child properties express a relationship of composition.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/hw/qdev.c b/hw/qdev.c
index 2519f00787..167f459996 100644
--- a/hw/qdev.c
+++ b/hw/qdev.c
@@ -1174,6 +1174,32 @@ DeviceState *qdev_get_root(void)
     return qdev_root;
 }
 
+static void qdev_get_child_property(DeviceState *dev, Visitor *v, void *opaque,
+                                    const char *name, Error **errp)
+{
+    DeviceState *child = opaque;
+    gchar *path;
+
+    path = qdev_get_canonical_path(child);
+    visit_type_str(v, &path, name, errp);
+    g_free(path);
+}
+
+void qdev_property_add_child(DeviceState *dev, const char *name,
+                             DeviceState *child, Error **errp)
+{
+    gchar *type;
+
+    type = g_strdup_printf("child<%s>", child->info->name);
+
+    qdev_property_add(dev, name, type, qdev_get_child_property,
+                      NULL, NULL, child, errp);
+
+    qdev_ref(child);
+
+    g_free(type);
+}
+
 static gchar *qdev_get_path_in(DeviceState *parent, DeviceState *dev)
 {
     DeviceProperty *prop;