pycloudd

#!/usr/bin/python3
# Copyright 2016 Year4000.
#
# 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 3 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.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

### BEGIN INIT INFO
# Provides:   pycloudd
# Required-Start: $local_fs $remote_fs $network
# Required-Stop:  $local_fs $remote_fs $network
# Default-Start:  4 5 6
# Default-Stop:   0 1 6
# Short-Description: Manages the PyCloud Daemon
# Description: Manages the PyCloud daemon by providing
#       a wrapper for common PyCloud tasks.
### END INIT INFO

import sys
import os
import time
import signal
from pycloud.constants import PID_FILE

USAGE = 'Usage: {0} {{start|stop|restart|force-reload|status}}'


class PyCloudError(BaseException):
    """ A basic error for PyCloud """

    def __init__(self, message, *args, **kwargs):
        self.__message = str(message).format(*args, **kwargs)

    def get_message(self):
        """ Get the formatted message of the error """
        return self.__message


def get_pid(throw=True):
    """ Get the pid or raise an exception """
    if os.path.exists(PID_FILE):
        with open(PID_FILE) as pid_file:
            return int(pid_file.read())
    else:
        if throw:
            raise PyCloudError('No process id file found: {0}', PID_FILE)
        else:
            return False


def is_pid_running(process_id):
    """ Check if the id is a running process """
    try:
        os.kill(process_id, 0)
    except OSError:
        return False
    else:
        return True


def stop():
    """ Stop the PyCloud daemon """
    pid = -1

    try:
        pid = get_pid()
        os.kill(pid, signal.SIGABRT)
        print('PyCloud has been stopped...')
    except OSError:
        raise PyCloudError('Found process id {0} and PyCloud not running...', pid)
    finally:
        while pid > 0 and is_pid_running(pid):
            time.sleep(0.25)

        if os.path.exists(PID_FILE):
            os.remove(PID_FILE)


def start():
    """ Start the PyCloud daemon """
    if get_pid(throw=False):
        raise PyCloudError('PyCloud is currently running...')
    else:
        os.system('sudo -u year4000 python3 -m pycloud.app --daemon')
        print('PyCloud has been started...')


def status():
    """ Get the status of the PyCloud daemon """
    if get_pid(throw=False):
        print('PyCloud is running...')
        return True
    else:
        print('PyCloud is not running...')
        return False


try:
    if os.getuid() != 0:
        raise PyCloudError('PyCloud must be ran as root user')

    if __name__ == "__main__" and len(sys.argv) > 1:
        argument = sys.argv[1]

        if argument == 'start':
            start()
        elif argument == 'stop':
            stop()
        elif argument == 'status':
            status()
        elif argument == 'restart':
            stop()
            start()
        elif argument == 'force-reload':
            try:
                stop()
            except PyCloudError as error:
                print('An error has been suppressed: ' + error.get_message())
                pass
            finally:
                start()
        else:
            raise PyCloudError(USAGE, sys.argv[0])
    else:
        raise PyCloudError(USAGE, sys.argv[0])
except PyCloudError as error:
    print(error.get_message())
    sys.exit(1)