Bug with Python UTF-16 output and Windows line endings?

Question

With this code:

test.py

import sys
import codecs

sys.stdout = codecs.getwriter('utf-16')(sys.stdout)

print "test1"
print "test2"

Then I run it as:

test.py > test.txt

In Python 2.6 on Windows 2000, I'm finding that the newline characters are being output as the byte sequence \x0D\x0A\x00 which of course is wrong for UTF-16.

Am I missing something, or is this a bug?

Answer 1

The newline translation is happening inside the stdout file. You're writing "test1\n" to sys.stdout (a StreamWriter). StreamWriter translates this to "t\x00e\x00s\x00t\x001\x00\n\x00", and sends it to the real file, the original sys.stderr.

That file doesn't know that you've converted the data to UTF-16; all it knows is that any \n values in the output stream need to be converted to \x0D\x0A, which results in the output you're seeing.

Answer 2

I've found two solutions so far, but not one that gives output of UTF-16 with Windows-style line endings.

First, to redirect Python print statements to a file with UTF-16 encoding (output Unix style line-endings):

import sys
import codecs

sys.stdout = codecs.open("outputfile.txt", "w", encoding="utf16")

print "test1"
print "test2"

Second, to redirect to stdout with UTF-16 encoding, without line-ending translation corruption (output Unix style line-endings) (thanks to this ActiveState recipe):

import sys
import codecs

sys.stdout = codecs.getwriter('utf-16')(sys.stdout)

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

print "test1"
print "test2"

Answer 3

Try this:

import sys
import codecs

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

class CRLFWrapper(object):
    def __init__(self, output):
        self.output = output

    def write(self, s):
        self.output.write(s.replace("\n", "\r\n"))

    def __getattr__(self, key):
        return getattr(self.output, key)

sys.stdout = CRLFWrapper(codecs.getwriter('utf-16')(sys.stdout))
print "test1"
print "test2"