ledd.py

#!/usr/bin/python3

# LEDD Project
# Copyright (C) 2015 LEDD Team
#
# 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/>.

"""LedD Daemon

Usage:
  ledd.py [--detach] [-d | --debug] [-v | --verbose]
  ledd.py -h | --help
  ledd.py --version

Options:
  -h --help         Show this screen.
  --version         Show version.
  -d --debug        Show debug output. (not recommended)
  -v --verbose      Be verbose.
  --detach          Detach after start.
"""

import logging
import sys
import os
from pkgutil import iter_modules

import coloredlogs
from docopt import docopt

import ledd.daemon
import ledd

if "smbus" not in (name for loader, name, ispkg in iter_modules()):
    print("smbus not found, installing replacement")


    class SMBus:
        def __init__(self, i2c_address):
            self.i2c_address = i2c_address
            self.channels = {}

        def write_word_data(self, addr, cmd, val):
            if (cmd - 6) % 4 == 0:
                self.channels[(cmd - 6) // 4] = val

        def read_word_data(self, addr, cmd):
            if (cmd - 8) // 4 not in self.channels:
                self.channels[(cmd - 8) // 4] = 0
            return self.channels[(cmd - 8) // 4]


    class SMBusModule:
        SMBus = SMBus


    sys.modules['smbus'] = SMBusModule
    sys.modules['smbus'].SMBus = SMBus


def pid_exists(processid):
    if processid < 0:
        return False
    try:
        os.kill(processid, 0)
    except ProcessLookupError:
        return False
    except PermissionError:
        return True
    else:
        return True


if __name__ == "__main__":
    arguments = docopt(__doc__, version='LedD Daemon ' + ledd.VERSION)
    lvl = logging.WARNING

    if arguments['--verbose']:
        lvl = logging.INFO

    if arguments['--debug']:
        lvl = logging.DEBUG

    log = logging.getLogger(__name__)
    coloredlogs.install(level=lvl)

    try:
        with open('ledd.pid', 'r') as f:
            spid = f.read()
            if spid:
                if pid_exists(int(spid)):
                    log.fatal("A instance of the program is already running, exiting...")
                    sys.exit(5)
                else:
                    log.warning("Found stale pid file, assuming unclean shutdown.")
    except FileNotFoundError:
        pass

    if arguments['--detach']:
        wdir = os.path.dirname(os.path.realpath(__file__))
        try:
            pid = os.fork()
            if pid == 0:
                os.setsid()
                pid2 = os.fork()
                if pid2 == 0:
                    os.umask(0)
                    os.chdir(wdir)
                    with open("ledd.pid", 'w') as pidf:
                        pidf.write(str(os.getpid()) + '\n')
                    ledd.daemon.run()
                else:
                    sys.exit()
            else:
                sys.exit()
        except OSError as e:
            log.fatal("Start failed: %s", e)
    else:
        ledd.daemon.run()