Source code for util.customsubprocess

# Copyright (c) 2015 Intracom S.A. Telecom Solutions. All rights reserved.
#
# This program and the accompanying materials are made available under the
# terms of the Eclipse Public License v1.0 which accompanies this distribution,
# and is available at http://www.eclipse.org/legal/epl-v10.html

""" Extended subprocess functionality """

import logging
import subprocess


def check_output_streaming(cmd, prefix='', queue=None, block_flag=True):
    """
    Redirect output to stderr, printing it whenever a new line is detected \
        (bufsize=1 denotes line buffered output). This can be considered as \
        "realtime" printing. Additionally, prints output by prepending it with \
         a user-defined prefix. Furthermore, it optionally forwards output to \
         a queue in order e.g. to be processed by a separate thread in \
         real-time.

    :param cmd: the command line list.
    :param prefix: the user defined prefix for output.
    :param queue: queue to forward console output to.
    :param block_flag: defines if the execution will be performed in block mode
    :returns: return exit status of command.
    :raises subprocess.CalledProcessError: If the exit status of the executed \
        command is not 0.
    :rtype: int
    :type cmd: list<str>
    :type prefix: str
    :type queue: multiprocessing.Queue
    :type block_flag: bool
    """

    if block_flag:
        proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                                stderr=subprocess.STDOUT, bufsize=1,
                                universal_newlines=True)

        for line in iter(proc.stdout.readline, ''):
            if queue is not None:
                queue.put(line)
            logging.debug('{0} {1}'.format(prefix, line.rstrip()))

        proc.wait()
        if proc.returncode != 0:
            raise subprocess.CalledProcessError(proc.returncode, cmd)
        else:
            return proc.returncode
    else:
        subprocess.Popen(cmd, shell=True, stdin=None, stdout=None, stderr=None,
                        close_fds=True)