[issue9560] platform.py: use -b option for file command in _syscmd_file()

[STINNER Victor]

STINNER Victor <victor.stinner at haypocalc.com> added the comment:

> Looking at the only use case of _syscmd_file(), it may not even 
> be worth the trouble of adding the -b option. Fixing the doc-string 
> may be enough: (...)

Well, my problem is that _syscmd_file() fails with a non encodable filename on Linux because the file program writes the filename to stdout, but os.popen() is unable to parse it because the filename is not decodable from the filesystem encoding (without surrogateescape).

I would like to add -b option just to avoid this encoding problem.

The bug:
---
$ cp /bin/ls $(echo -ne "ls-\x80")
$ ./python -c "import platform; platform.architecture(executable='ls-\uDC80')"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/SHARE/SVN/py3k/Lib/platform.py", line 1059, in architecture
    output = _syscmd_file(executable, '')
  File "/home/SHARE/SVN/py3k/Lib/platform.py", line 1006, in _syscmd_file
    output = f.read().strip()
  File "/home/SHARE/SVN/py3k/Lib/codecs.py", line 300, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x80 in position 24: invalid start byte
---

See also #8611 and #9425.

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue9560>
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