monitor: fix qmp/hmp query-memdev not reporting IDs of memory backends

Considering 'id' is mandatory for user_creatable objects/backends
and user_creatable_add_type() always has it as an argument
regardless of where from it is called CLI/monitor or QMP,
Fix issue by adding 'id' property to hostmem backends and
set it in user_creatable_add_type() for every object that
implements 'id' property. Then later at query-memdev time
get 'id' from object directly.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <1484052795-158195-4-git-send-email-imammedo@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
diff --git a/backends/hostmem.c b/backends/hostmem.c
index 4256d24..7f5de70 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -348,6 +348,24 @@
     }
 }
 
+static char *get_id(Object *o, Error **errp)
+{
+    HostMemoryBackend *backend = MEMORY_BACKEND(o);
+
+    return g_strdup(backend->id);
+}
+
+static void set_id(Object *o, const char *str, Error **errp)
+{
+    HostMemoryBackend *backend = MEMORY_BACKEND(o);
+
+    if (backend->id) {
+        error_setg(errp, "cannot change property value");
+        return;
+    }
+    backend->id = g_strdup(str);
+}
+
 static void
 host_memory_backend_class_init(ObjectClass *oc, void *data)
 {
@@ -377,6 +395,13 @@
         HostMemPolicy_lookup,
         host_memory_backend_get_policy,
         host_memory_backend_set_policy, &error_abort);
+    object_class_property_add_str(oc, "id", get_id, set_id, &error_abort);
+}
+
+static void host_memory_backend_finalize(Object *o)
+{
+    HostMemoryBackend *backend = MEMORY_BACKEND(o);
+    g_free(backend->id);
 }
 
 static const TypeInfo host_memory_backend_info = {
@@ -387,6 +412,7 @@
     .class_init = host_memory_backend_class_init,
     .instance_size = sizeof(HostMemoryBackend),
     .instance_init = host_memory_backend_init,
+    .instance_finalize = host_memory_backend_finalize,
     .interfaces = (InterfaceInfo[]) {
         { TYPE_USER_CREATABLE },
         { }