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+# This file is part of jwmud, written by Helmut Pozimski in 2014.
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+#
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+# jwmud is free software: you can redistribute it and/or modify
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+# it under the terms of the GNU General Public License as published by
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+# the Free Software Foundation, version 2 of the License.
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+#
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+# jwmud is distributed in the hope that it will be useful,
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+# but WITHOUT ANY WARRANTY; without even the implied warranty of
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+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+# GNU General Public License for more details.
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+#
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+# You should have received a copy of the GNU General Public License
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+# along with jwmud. If not, see <http://www.gnu.org/licenses/>.
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+
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+# -*- coding: utf8 -*-
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+
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+import os
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+import sys
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+
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+
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+class Daemon(object):
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+ """ Tries to implement a well behaving unix daemon in a generic way,
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+ so the code could be used in different projects.
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+
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+ """
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+
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+ def __init__(self, pfile_path, pfile_name):
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+ """ Initializes the object. """
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+ self.__pfile_path = pfile_path
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+ self.__pfile_name = pfile_name
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+ self.__daemon = False
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+ self.__pid = 0
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+ self.__pidfile = ""
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+
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+ def Daemonize(self):
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+ """ Turns the calling process into a daemon running on it's own """
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+
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+ try:
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+ # Fork for the first time
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+ self.__pid = os.fork()
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+ except OSError:
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+ sys.exit(os.EX_OSERR)
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+ else:
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+ if self.__pid > 0:
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+ sys.exit(os.EX_OK)
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+ # Become session and group leader
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+ # noinspection PyArgumentList
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+ os.setsid()
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+ try:
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+ #Fork for the second time
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+ self.__pid = os.fork()
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+ except OSError:
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+ sys.exit(os.EX_OSERR)
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+ else:
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+ if self.__pid > 0:
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+ sys.exit(os.EX_OK)
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+ # Change cwd to / to avoid interfering with other mounted file systems
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+ os.chdir("/")
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+ # Reset the umask
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+ os.umask(0)
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+
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+ # Close possibly open file descriptors
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+ os.close(0)
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+ os.close(1)
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+ os.close(2)
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+
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+ # And redirect them to /dev/null
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+ os.open("/dev/null", 0)
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+ os.open("/dev/null", 1)
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+ os.open("/dev/null", 2)
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+
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+ self.__daemon = True
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+
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+ def DropPriv(self, uid, gid):
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+ """ If the daemon is running as root user, drop privileges and continue
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+ running as the defined unprivileged user """
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+ if os.getuid() == 0:
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+ os.setgid(gid)
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+ os.setuid(uid)
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+
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+ def SetName(self, name, cmdline):
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+ """ Sets the name of the process shown visible in ps and top,
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+ this allows to make your daemon look more like a standalone
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+ program instead of a python script.
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+
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+ """
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+ try:
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+ # First check if prctl is available, otherwise this
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+ # function does nothing
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+ # noinspection PyUnresolvedReferences
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+ import prctl
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+ except ImportError:
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+ return False
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+ else:
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+ prctl.set_name(name)
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+ prctl.set_proctitle(cmdline)
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+ return True
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+
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+ def Start(self):
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+ """ Performs the operations needed to "start" the daemon """
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+ if self.__daemon is True:
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+ if os.access(self.__pfile_path, os.F_OK & os.W_OK):
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+ self.__pidfile = open(os.path.join(self.__pfile_path,
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+ self.__pfile_name), "w")
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+ self.__pidfile.write(str(os.getpid()) + "\n")
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+ self.__pidfile.close()
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+ return True
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+ else:
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+ return False
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+ else:
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+ return False
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+
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+ def Stop(self):
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+ """ Performs the operations needed to stop the daemon """
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+ if self.__daemon is True:
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+ try:
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+ os.remove(os.path.join(self.__pfile_path, self.__pfile_name))
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+ except OSError:
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+ return False
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+ else:
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+ return True
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+ else:
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+ return True
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