Fix for 699654 breaks exception handling if args is empty

[Vish Ishaya]

The fix for 699654 which uses exception.args[0] breaks if args is empty and covers up the underlying exception. For example:

Traceback (most recent call last):
 File "/usr/lib/pymodules/python2.6/eventlet/wsgi.py", line 336, in handle_one_response
   result = self.application(self.environ, start_response)
 File "/usr/lib/pymodules/python2.6/paste/urlmap.py", line 203, in __call__
   return app(environ, start_response)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 147, in __call__
   resp = self.call_func(req, *args, **self.kwargs)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 208, in call_func
   return self.func(req, *args, **kwargs)
 File "/usr/lib/pymodules/python2.6/nova/api/ec2/__init__.py", line 59, in __call__
   rv = req.get_response(self.application)
 File "/usr/lib/pymodules/python2.6/webob/request.py", line 919, in get_response
   application, catch_exc_info=False)
 File "/usr/lib/pymodules/python2.6/webob/request.py", line 887, in call_application
   app_iter = application(self.environ, start_response)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 159, in __call__
   return resp(environ, start_response)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 159, in __call__
   return resp(environ, start_response)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 159, in __call__
   return resp(environ, start_response)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 147, in __call__
   resp = self.call_func(req, *args, **self.kwargs)
 File "/usr/lib/pymodules/python2.6/webob/dec.py", line 208, in call_func
   return self.func(req, *args, **kwargs)
 File "/usr/lib/pymodules/python2.6/nova/api/ec2/__init__.py", line 328, in __call__
   LOG.exception(_('Unexpected error raised: %s'), ex.args[0],
IndexError: tuple index out of range

Perhaps we should coerce the exceptions to unicode instead?

[Tushar Patil (tpatil)]

Please test with the below patch. If see any problem in this patch please let me know. Thanks.

=== modified file 'nova/api/ec2/__init__.py'
--- nova/api/ec2/__init__.py 2011-01-27 22:10:42 +0000
+++ nova/api/ec2/__init__.py 2011-01-29 00:03:03 +0000
@@ -171,7 +171,7 @@
                     req.path)
         # Be explicit for what exceptions are 403, the rest bubble as 500
         except (exception.NotFound, exception.NotAuthorized) as ex:
- LOG.audit(_("Authentication Failure: %s"), ex.args[0])
+ LOG.audit(_("Authentication Failure: %s"), utils.utf8(ex))
             raise webob.exc.HTTPForbidden()

         # Authenticated!
@@ -316,30 +316,31 @@
         try:
             result = api_request.invoke(context)
         except exception.InstanceNotFound as ex:
- LOG.info(_('InstanceNotFound raised: %s'), ex.args[0],
+ LOG.info(_('InstanceNotFound raised: %s'), utils.utf8(ex),
                      context=context)
             ec2_id = cloud.id_to_ec2_id(ex.instance_id)
             message = _('Instance %s not found') % ec2_id
             return self._error(req, context, type(ex).__name__, message)
         except exception.VolumeNotFound as ex:
- LOG.info(_('VolumeNotFound raised: %s'), ex.args[0],
+ LOG.info(_('VolumeNotFound raised: %s'), utils.utf8(ex),
                      context=context)
             ec2_id = cloud.id_to_ec2_id(ex.volume_id, 'vol-%08x')
             message = _('Volume %s not found') % ec2_id
             return self._error(req, context, type(ex).__name__, message)
         except exception.NotFound as ex:
- LOG.info(_('NotFound raised: %s'), ex.args[0], context=context)
- return self._error(req, context, type(ex).__name__, ex.args[0])
+ LOG.info(_('NotFound raised: %s'), utils.utf8(ex), context=context)
+ return self._error(req, context, type(ex).__name__, utils.utf8(ex))
         except exception.ApiError as ex:
- LOG.exception(_('ApiError raised: %s'), ex.args[0],
+ LOG.exception(_('ApiError raised: %s'), utils.utf8(ex),
                           context=context)
             if ex.code:
- return self._error(req, context, ex.code, ex.args[0])
+ return self._error(req, context, ex.code, utils.utf8(ex))
             else:
- return self._error(req, context, type(ex).__name__, ex.args[0])
+ return self._error(req, context, type(ex).__name_,
+ utils.utf8(ex))
         except Exception as ex:
             extra = {'environment': req.environ}
- LOG.exception(_('Unexpected error raised: %s'), ex.args[0],
+ LOG.exception(_('Unexpected error raised: %s'), utils.utf8(ex),
                           extra=extra, context=context)
             return self._error(req,
                                context,

=== modified file 'nova/utils.py'
--- nova/utils.py 2011-01-27 19:52:10 +0000
+++ nova/utils.py 2011-01-28 23:45:43 +0000
@@ -405,6 +405,12 @@
     """
     if isinstance(value, unicode):
         return value.encode...