[Patches] [ python-Patches-1603907 ] subprocess: error redirecting i/o from non-console process

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Patches item #1603907, was opened at 2006-11-27 18:20
Message generated for change (Comment added) made by astrand
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Category: Library (Lib)
Group: Python 2.6
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Oren Tirosh (orenti)
Assigned to: Peter Åstrand (astrand)
Summary: subprocess: error redirecting i/o from non-console process 

Initial Comment:
In IDLE, PythonWin or other non-console interactive Python under Windows:

>>> from subprocess import *
>>> Popen('cmd', stdout=PIPE)

Traceback (most recent call last):
  File "<pyshell#11>", line 1, in -toplevel-
    Popen('', stdout=PIPE)
  File "C:\python24\lib\subprocess.py", line 533, in __init__
    (p2cread, p2cwrite,
  File "C:\python24\lib\subprocess.py", line 593, in _get_handles
    p2cread = self._make_inheritable(p2cread)
  File "C:\python24\lib\subprocess.py", line 634, in _make_inheritable
    DUPLICATE_SAME_ACCESS)
TypeError: an integer is required

The same command in a console windows is successful.

Why it happens: 
subprocess assumes that GetStdHandle always succeeds but when there is no console it returns None. DuplicateHandle then complains about getting a non-integer. This problem does not happen when redirecting all three standard handles.

Solution:
Replace None with -1 (INVALID_HANDLE_VALUE) in _make_inheritable.

Patch attached.

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>Comment By: Peter Åstrand (astrand)
Date: 2007-01-07 11:58

Message:
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user_id=344921
Originator: NO

This patch looks very interesting. However, it feels a little bit strange
to call DuplicateHandle with a handle of -1. Is this really allowed? What
will DuplicateHandle return in this case? INVALID_HANDLE_VALUE? In that
case, isn't it better to return INVALID_HANDLE_VALUE directly? 


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