Fix XML UnicodeEncode serialization error

The generic Nova XMLSerializer code will currently attempt
to cast to str the value for all leaf nodes. This patch
ensures that no attempt is made to convert unicode which
can cause a UnicodeEncode error. We don't need to convert
unicode for XML text and regardless we encode to UTF-8 at
a later point.

Change-Id: I8135d2b9a67db62b0eafdd301b7fdb67a5dd72cc
Closes-Bug: #1279172
(cherry picked from commit 53fe869631)
(cherry picked from commit 3136cfc11f)

nova/api/openstack/wsgi.py

@@ -435,7 +435,9 @@ class XMLDictSerializer(DictSerializer):
                     result.appendChild(node)
         else:
             # Type is atom
-            node = doc.createTextNode(str(data))
+            if not isinstance(data, six.string_types):
+                data = six.text_type(data)
+            node = doc.createTextNode(data)
             result.appendChild(node)
         return result
 

nova/tests/api/openstack/test_wsgi.py

@@ -221,6 +221,14 @@ class XMLDictSerializerTest(test.NoDBTestCase):
         result = result.replace('\n', '').replace(' ', '')
         self.assertEqual(result, expected_xml)
 
+    def test_xml_contains_unicode(self):
+        input_dict = dict(test=u'\u89e3\u7801')
+        expected_xml = '<test>\xe8\xa7\xa3\xe7\xa0\x81</test>'
+        serializer = wsgi.XMLDictSerializer()
+        result = serializer.serialize(input_dict)
+        result = result.replace('\n', '').replace(' ', '')
+        self.assertEqual(expected_xml, result)
+
 
 class JSONDictSerializerTest(test.NoDBTestCase):
     def test_json(self):