Encode error messages before sending them to stdout

When an error with non-ascii characters is caught by glanceclient, it
fails at printing it and exists with a UnicodeEncodedError. This patch
encodes errors' messages using strutils before sending them to stdout.

Fixes bug: #1200206

Change-Id: I4dabcd76ffb258840bd6a66ad23c030f34960e86

glanceclient/common/utils.py

@@ -202,3 +202,15 @@ def getsockopt(self, *args, **kwargs):
     lands in mainstream packages.
     """
     return self.fd.getsockopt(*args, **kwargs)
+
+
+def exception_to_str(exc):
+    try:
+        error = unicode(exc)
+    except UnicodeError:
+        try:
+            error = str(exc)
+        except UnicodeError:
+            error = ("Caught '%(exception)s' exception." %
+                     {"exception": exc.__class__.__name__})
+    return strutils.safe_encode(error, errors='ignore')

glanceclient/shell.py

@@ -472,5 +472,5 @@ def main():
         print >> sys.stderr, '... terminating glance client'
         sys.exit(1)
     except Exception as e:
-        print >> sys.stderr, e
+        print >> sys.stderr, utils.exception_to_str(e)
         sys.exit(1)

tests/test_utils.py

@@ -93,3 +93,18 @@ class TestUtils(testtools.TestCase):
 | Key      | Value |
 +----------+-------+
 ''')
+
+    def test_exception_to_str(self):
+        class FakeException(Exception):
+            def __str__(self):
+                raise UnicodeError()
+
+        ret = utils.exception_to_str(Exception('error message'))
+        self.assertEqual(ret, 'error message')
+
+        ret = utils.exception_to_str(Exception('\xa5 error message'))
+        self.assertEqual(ret, ' error message')
+
+        ret = utils.exception_to_str(FakeException('\xa5 error message'))
+        self.assertEqual(ret, "Caught '%(exception)s' exception." %
+                         {'exception': 'FakeException'})