twisted.python.test.test_sendmsg.SendmsgTestCase.test_sendSubProcessFD() fails in Twisted 12.1.0

	Arfrever reported
Trac ID	trac#5702
Type	defect
Created	2012-06-06 02:44:25Z

twisted.python.test.test_sendmsg.SendmsgTestCase.test_sendSubProcessFD() has been introduced in Twisted 12.1.0 and fails.

  GetSocketFamilyTests
    test_badArguments ...                                                  [OK]
    test_inet ...                                                          [OK]
    test_inet6 ...                                                         [OK]
    test_syscallError ...                                                  [OK]
    test_unix ...                                                          [OK]
  RecvmsgTestCase
    test_badArguments ...                                                  [OK]
    test_cmsgSpaceOverflow ...                                             [OK]
    test_flags ...                                                         [OK]
    test_syscallError ...                                                  [OK]
  SendmsgTestCase
    test_badAncillaryIter ...                                              [OK]
    test_badAncillaryNext ...                                              [OK]
    test_flags ...                                                         [OK]
    test_roundtrip ...                                                     [OK]
    test_roundtripEmptyAncillary ...                                       [OK]
    test_sendSubProcessFD ...                                           [ERROR]
    test_sendmsgBadAncillaryItem ...                                       [OK]
    test_sendmsgBadArguments ...                                           [OK]
    test_shortsend ...                                                     [OK]
    test_syscallError ...                                                  [OK]
    test_syscallErrorWithControlMessage ...                                [OK]
    test_wrongTypeAncillary ...                                            [OK]

===============================================================================
[ERROR]
Traceback (most recent call last):
Failure: twisted.python.test.test_sendmsg.ExitedWithStderr: 
Traceback (most recent call last):
  File "/var/tmp/portage/dev-python/twisted-12.1.0-r1000/temp/tests-2.7/usr/lib64/python2.7/site-packages/twisted/python/test/pullpipe.py", line 38, in <module>
    fd, description = recvfd(int(sys.argv[1]))
  File "/var/tmp/portage/dev-python/twisted-12.1.0-r1000/temp/tests-2.7/usr/lib64/python2.7/site-packages/twisted/python/test/pullpipe.py", line 29, in recvfd
    [(cmsg_level, cmsg_type, packedFD)] = ancillary
ValueError: need more than 0 values to unpack



twisted.python.test.test_sendmsg.SendmsgTestCase.test_sendSubProcessFD
-------------------------------------------------------------------------------
Ran 21 tests in 0.212s

FAILED (errors=1, successes=20)

trac-id__5702 5702
type__defect defect
reporter__Arfrever Arfrever
priority__normal normal
milestone__ 
branch__ 
branch_author__ 
status__new new
resolution__None None
component__core core
keywords__ 
time__1338950665000000 1338950665000000
changetime__1339013732000000 1339013732000000
version__None None
owner__ 
cc__Arfrever

Start by running twisted.python.test.test_sendmsg.SendmsgTestCase.test_sendSubProcessFD and inspect twisted/python/test/pullpipe.py, especially recvfd where the ancillary data is unpacked. Compare the failing subprocess FD path with the passing sendmsg tests. Done means the named test passes without the ValueError while the other sendmsg tests remain passing.