makefile.py

# -*- coding: utf-8 -*-
"""
backports.makefile
~~~~~~~~~~~~~~~~~~

Backports the Python 3 ``socket.makefile`` method for use with anything that
wants to create a "fake" socket object.
"""
import io

from socket import SocketIO


def backport_makefile(self, mode="r", buffering=None, encoding=None,
                      errors=None, newline=None):
    """
    Backport of ``socket.makefile`` from Python 3.5.
    """
    if not set(mode) <= {"r", "w", "b"}:
        raise ValueError(
            "invalid mode %r (only r, w, b allowed)" % (mode,)
        )
    writing = "w" in mode
    reading = "r" in mode or not writing
    assert reading or writing
    binary = "b" in mode
    rawmode = ""
    if reading:
        rawmode += "r"
    if writing:
        rawmode += "w"
    raw = SocketIO(self, rawmode)
    self._makefile_refs += 1
    if buffering is None:
        buffering = -1
    if buffering < 0:
        buffering = io.DEFAULT_BUFFER_SIZE
    if buffering == 0:
        if not binary:
            raise ValueError("unbuffered streams must be binary")
        return raw
    if reading and writing:
        buffer = io.BufferedRWPair(raw, raw, buffering)
    elif reading:
        buffer = io.BufferedReader(raw, buffering)
    else:
        assert writing
        buffer = io.BufferedWriter(raw, buffering)
    if binary:
        return buffer
    text = io.TextIOWrapper(buffer, encoding, errors, newline)
    text.mode = mode
    return text