sys.stdout is opened as text on Windows

[techtonik]

On Windows, if you try to pipe binary data from Python into external file, the file will be broken, because all linefeed characters \n will be converted to \n\r.

test1.py:

import sys
bindata = "_\x0a_"
sys.stdout.write(bindata)

> python test1.py > data.bin
> python -c "print(len('_\x0a_'))"
3
> python -c "print(len(open('data.bin', 'rb').read()))"
4

The fix is to use Windows API to set stdout and stderr streams to binary:

import sys

if sys.platform == "win32":
    import os, msvcrt
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)