eryksun added the comment:
> It is not clear why the absence of _setmode(fd, os.O_BINARY)
> is not detected by tests.
It's only a problem when an existing text-mode file descriptor is passed in.
For example, in text mode the CRT handles b'\x1a' as an EOF marker:
Python 3.5.0b4 (v3.5.0b4:c0d641054635, Jul 26 2015, 07:11:12)
[MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os, _pyio
>>> _ = open('testfile', 'wb').write(b'abc\x1adef')
>>> fd = os.open('testfile', os.O_RDONLY|os.O_TEXT)
>>> f = _pyio.open(fd, 'rb')
>>> f.read()
b'abc'
>>> f.close()
>>> f = _pyio.open('testfile', 'rb')
>>> f.read()
b'abc\x1adef'
The setmode call ensures a file descriptor is in the expected binary mode:
>>> import msvcrt
>>> fd = os.open('testfile', os.O_RDONLY|os.O_TEXT)
>>> old_mode = msvcrt.setmode(fd, os.O_BINARY)
>>> old_mode == os.O_TEXT
True
>>> f = _pyio.open(fd, 'rb')
>>> f.read()
b'abc\x1adef'
----------
nosy: +eryksun
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue24881>
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