[Twisted-Python] Negative error code breaks twisted.conch

[Peter Westlake]

Thank you!

Filed: https://twistedmatrix.com/trac/ticket/9573

I'll go off and read about submitting a fix now.

Peter.

On Tue, 15 Jan 2019, at 07:41, Glyph wrote:
> 
> 
>> On Jan 14, 2019, at 7:23 AM, Peter Westlake
>> <peter.westlake at pobox.com> wrote:>> 
>> An SSCCE:
>> 
>> from twisted.internet import error
>> from twisted.python import failure
>> from twisted.conch.ssh.session import SSHSessionProcessProtocol
>> from mock import MagicMock
>> 
>> err = error.ProcessTerminated(-1)
>> fail = failure.Failure(err)
>> session = MagicMock()
>> proto = SSHSessionProcessProtocol(session)
>> proto.processEnded(fail)
>> 
>> 
>> That fails with:
>> 
>> Traceback (most recent call last):
>>   File ".../negexit.py", line 10, in <module>
>>     proto.processEnded(fail)
>>   File "/usr/lib64/python2.7/site-
>>   packages/twisted/conch/ssh/session.py", line 279, in processEnded>>     struct.pack('>L', err.exitCode))
>> struct.error: integer out of range for 'L' format code
>> 
>> I'm running an SSH server on Windows, where negative exit codes can
>> happen.>> 
>> Passing negative numbers to a ">L" format was allowed in Python
>> before 2.6, where the number was treated as an unsigned int of the
>> same bit pattern. It was deprecated in 2.6, and became an error in
>> 2.7. It's only just become a problem for me because I'm updating a 10
>> year old SSH server that has been running under 2.4 all this time.>> 
>> Presumably the fix is to bit-mask the exitCode? I was able to work
>> around the error by doing that in a copy of _dumbwin32proc.py which
>> was copied into the project (historical reasons, don't ask) but it
>> would be nice to have a proper upstream fix. Not least because I want
>> to purge the copied-in file, as you can imagine.> This is a great bug!  Thanks for raising it.  Sounds like the fix is
> to simply reinterpret it as unsigned.
> https://en.wikipedia.org/wiki/Exit_status#Windows:> 
>>>> Windows uses 32-bit unsigned integers as exit codes,[11] although
>>>> the command interpreter treats them as signed.[12] If a process
>>>> fails initialization, a Windows system error code may be
>>>> returned.[13][14]> 
> Please do submit this fix upstream (file a ticket on Trac, open a PR,
> etc), it seems like one of the easier ones to integrate :-).> 
> -g
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