[Patches] [ python-Patches-788404 ] ignore "b" and "t" mode modifiers in posix_popen

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Patches item #788404, was opened at 2003-08-14 00:53
Message generated for change (Settings changed) made by loewis
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Category: Library (Lib)
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: Andrew Gaul (gaul)
>Assigned to: Martin v. Löwis (loewis)
Summary: ignore "b" and "t" mode modifiers in posix_popen

Initial Comment:
Fixes bug 703198.  This patch removes any "b" or "t"

modifiers, which have meaning in Windows (binary and

text modes, respectively), but not in POSIX.  This

allows users to write portable code between Windows and

POSIX when working on binary data in pipes:

os.popen(cmd, 'rb').

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Comment By: Andrew Gaul (gaul)
Date: 2003-09-01 14:13

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*puzzles over why patch is so backward*  Yes, it modifies an

immutable object - double plus ungood.  Attached is a

simpler patch which does the right thing.  Sorry, I do not

know what was going through my head at the time.  My best

guess was that I thought that mode was a safe, mutable copy

of the immutable Python string and I wanted to allow modes

like "br", which the MSDN docs actually say are invalid ('b'

and 't' modifiers must be appended).



Note that the behaviour of POSIX posix_popen in this patch

differs from Windows posix_popen, as the latter allows

treats "rw", "r+", and "rr" as "r".  In all three cases,

POSIX systems throw "OSError: [Errno 22] Invalid argument"

at pipe creation.  In the case of "rw", Windows systems

throw "IOError: [Errno 9] Bad file descriptor" when the

read-only pipe is first written to.  Ideally, Windows

posix_popen should be modified to the new POSIX behaviour to

give earlier error reporting.

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Comment By: Martin v. Löwis (loewis)
Date: 2003-08-31 18:42

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Maybe I'm mistaken: Does this patch really modify the string

object that is being passed? This would not be good: strings

are immutable.

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