Backport of Python 3.8 subprocess for 2.7 with improvements

subprocess.py

#!/usr/bin/env python2

"""Backport of Python 3.8 subprocess for 2.7 with improvements."""

from __future__ import print_function

__all__ = ("run",)

from subprocess import PIPE, Popen as _Popen27


# TODO: check bufsize arg


class Popen(_Popen27):
    def __enter__(self):
        return self

    def __exit__(self, exc_type, value, traceback):
        if self.stdout:
            self.stdout.close()
        if self.stderr:
            self.stderr.close()
        try:
            if self.stdin:
                self.stdin.close()
        finally:
            self.wait()


def run(args, input=None, check=True, universal_newlines=True):
    with Popen(args, stdout=PIPE, stderr=PIPE, universal_newlines=universal_newlines) as proc:
        try:
            stdoutdata, stderrdata = proc.communicate(input=input)
        except:
            proc.kill()
        retcode = proc.poll()
        if check and retcode:
            raise CalledProcessError(retcode, args, output=stdoutdata, stderr=stderrdata)
        return CompletedProcess(args, retcode, stdoutdata, stderrdata)


class CompletedProcess(object):
    def __init__(self, args, returncode, stdout=None, stderr=None):
        self.args = args
        self.returncode = returncode
        self.stdout = stdout
        self.stderr = stderr

    def check_returncode(self):
        if self.returncode:
            raise CalledProcessError(self.returncode, self.args, self.stdout, self.stderr)

    def __repr__(self):
        return "{}({})".format(type(self).__name__, 'returncode={!r}'.format(self.returncode))


class CalledProcessError(Exception):
    def __init__(self, returncode, cmd, output=None, stderr=None):
        self.returncode = returncode
        self.cmd = cmd
        self.output = output
        self.stderr = stderr

    def __str__(self):
        return "Command '%s' returned non-zero exit status %d" % (self.cmd, self.returncode)


if __name__ == "__main__":
    out = run(['ls', '-la'])
    print("stdout", out.stdout)
    print("stderr", out.stderr)
    print("returncode", out.returncode)