win-textfile

#!/usr/bin/env python3
#
# Copyright(C) 2020 Alex Mayfield
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
#
# Converts text files to a format usable by Windows Notepad.
#

import io
import sys

if len(sys.argv) < 3:
    print("Usage: win-textfile <src> <dest>")
    sys.exit(1)

src = open(sys.argv[1], "rb")
dest_stream = io.BytesIO()

# Check for BOM and if it doesn't exist, add it.
bom = src.read(3)
if (bom != b"\xef\xbb\xbf"):
    dest_stream.write(b"\xef\xbb\xbf")
src.seek(0)

# Read the text file byte by byte.
while True:
    byte = src.read(1)
    if (not byte):
        # End of file.
        break
    if (byte == b"\r"):
        # Found a CR, omit it so we don't double-up.
        continue
    if (byte == b"\n"):
        # Replace LF with CRLF.
        dest_stream.write(b"\r\n")
    else:
        # Everything else is copied verbatim.
        dest_stream.write(byte)

# Don't write file until last possible moment.
dest = open(sys.argv[2], "wb")
dest.write(dest_stream.getbuffer())