log-object: don't construct log ID with NULL self_id

If the object has an owner ID already but doesn't yet have enough
information to build its log ID, don't cache a less-than-useful
log ID string for it.

Signed-off-by: Dan Williams <dan@ioncontrol.co>

src/mm-log-object.c

@@ -63,7 +63,7 @@ mm_log_object_get_id (MMLogObject *self)
         gchar *self_id;
 
         self_id = MM_LOG_OBJECT_GET_IFACE (self)->build_id (self);
-        if (priv->owner_id) {
+        if (self_id && priv->owner_id) {
             priv->id = g_strdup_printf ("%s/%s", priv->owner_id, self_id);
             g_free (self_id);
         } else

src/mm-port.c

@@ -132,6 +132,9 @@ log_object_build_id (MMLogObject *_self)
     MMPort *self;
 
     self = MM_PORT (_self);
+    if (!self->priv->device || !self->priv->ptype)
+        return NULL;
+
     return g_strdup_printf ("%s/%s",
                             mm_port_get_device (self),
                             mm_port_type_get_string (mm_port_get_port_type (self)));