Normalize_time() always return naive object

Currently the timeutils.normalize_time() returns naive datetime
object when parameter timestamp is an naive object or a non-UTC
aware datetime object, and returns aware datetime object if
parameter timestamp is a UTC aware datetime object.

The basic problem here is that utcoffset() of None means the object is naive
but a utcoffset() of zero means that the object is aware but represents
UTC time.

This is fragile implementation and will trigger potential issue, because
aware/native datetime is not interoperatable. For example,
"timeutils.utcnow() > timeutils.normalize_time(m)" will success at most
time, while trigger TypeError if m is a UTC aware object.

We want to normalize all objects into naive objects.

Fixes bug 1048636

Change-Id: I4a09246fa8f0dd63ca54362b877aa825d9b79772
Signed-off-by: Yunhong, Jiang <yunhong.jiang@intel.com>

2 files changed, 24 insertions, 2 deletions

diff --git a/openstack/common/timeutils.py b/openstack/common/timeutils.py
index 9901a4c..93b34fc 100644
--- a/openstack/common/timeutils.py
+++ b/openstack/common/timeutils.py
@@ -62,9 +62,11 @@ def parse_strtime(timestr, fmt=PERFECT_TIME_FORMAT):
 
 
 def normalize_time(timestamp):
-    """Normalize time in arbitrary timezone to UTC"""
+    """Normalize time in arbitrary timezone to UTC naive object"""
     offset = timestamp.utcoffset()
-    return timestamp.replace(tzinfo=None) - offset if offset else timestamp
+    if offset is None:
+        return timestamp
+    return timestamp.replace(tzinfo=None) - offset
 
 
 def is_older_than(before, seconds):
diff --git a/tests/unit/test_timeutils.py b/tests/unit/test_timeutils.py
index 129609e..7e6ae72 100644
--- a/tests/unit/test_timeutils.py
+++ b/tests/unit/test_timeutils.py
@@ -214,3 +214,23 @@ class TestIso8601Time(unittest.TestCase):
         west = timeutils.parse_isotime(str)
         normed = timeutils.normalize_time(west)
         self._instaneous(normed, 2012, 2, 13, 23, 53, 07, 0)
+
+    def test_normalize_aware_to_naive(self):
+        dt = datetime.datetime(2011, 2, 14, 20, 53, 07)
+        str = '2011-02-14T20:53:07+21:00'
+        aware = timeutils.parse_isotime(str)
+        naive = timeutils.normalize_time(aware)
+        self.assertTrue(naive < dt)
+
+    def test_normalize_zulu_aware_to_naive(self):
+        dt = datetime.datetime(2011, 2, 14, 20, 53, 07)
+        str = '2011-02-14T19:53:07Z'
+        aware = timeutils.parse_isotime(str)
+        naive = timeutils.normalize_time(aware)
+        self.assertTrue(naive < dt)
+
+    def test_normalize_naive(self):
+        dt = datetime.datetime(2011, 2, 14, 20, 53, 07)
+        dtn = datetime.datetime(2011, 2, 14, 19, 53, 07)
+        naive = timeutils.normalize_time(dtn)
+        self.assertTrue(naive < dt)