#!/bin/env python

 # -*- coding: utf-8 -*-

 # ------------------------------------------------------------

 # autoshadow.py

 # 

 # Listen on DBus and mount any USB stick automatically

 # and invoke shadowfuse for it

 #

 # Autor: Oliver Maurhart, <oliver.maurhart@ait.ac.at>

 #

 # Copyright (C) 2013 AIT Austrian Institute of Technology

 # AIT Austrian Institute of Technology GmbH

 # Donau-City-Strasse 1 | 1220 Vienna | Austria

 # http://www.ait.ac.at

 #

 # 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 version 2.

 # 

 # 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, write to the Free Software

 # Foundation, Inc., 51 Franklin Street, Fifth Floor, 

 # Boston, MA  02110-1301, USA.

 # ------------------------------------------------------------

 # ------------------------------------------------------------

 # imports

 import argparse

 import dbus

 import dbus.glib

 import dbus.service

 import gobject

 import sys

 # ------------------------------------------------------------

 # const

 __version__ = "0.1"

 # ------------------------------------------------------------

 # code

 class AutoShadowService(dbus.service.Object):

     """The AutoShadowService is the DBus object which listens on UDisk2 events and decides to mount and shadow a device.

     This class incorporates a DBus service (at.ac.ait.opensecurity.AutoShadow) and binds

     itself to the /AutoShadow object.

     """

     def __init__(self):

         bus = dbus.SystemBus()

         bus_name = dbus.service.BusName('at.ac.ait.opensecurity.AutoShadow', bus)

         dbus.service.Object.__init__(self, bus_name, '/AutoShadow')

         # get the UDisk2 system object

         try:

             udisk2 = bus.get_object('org.freedesktop.UDisks2', '/org/freedesktop/UDisks2')

         except:

             sys.stderr.write('Failed to aquire DBus Service org.freedesktop.UDisks2 object /org/freedesktop/UDisks2 on system DBus.\n')

             sys.exit(1)

         # connect our signal

         udisk2.connect_to_signal('InterfacesAdded', self.interface_added, sender_keyword='sender')

     def interface_added(*args, **kwargs):

         """Entry point for signal for new interfaces"""

         # a new interface has been added

         object_path = args[1]

         interfaces_and_properties = args[2]

         interface_keys = interfaces_and_properties.keys()

         if (interface_keys[0] == 'org.freedesktop.UDisks2.Drive'):

             # added a new drive

             drive_values = interfaces_and_properties[interface_keys[0]]

             drive_id = str(drive_values['Id'])

             drive_vendor = str(drive_values['Vendor'])

             drive_removeable = bool(drive_values['Removable'])

             print('detected new drive: id=\'{0}\' vendor=\'{1}\' removeable={2}'.format(drive_id, drive_vendor, drive_removeable))

         if (interface_keys[0] == 'org.freedesktop.UDisks2.Block'):

             # added a new device - filesystem?

             if ('org.freedesktop.UDisks2.Filesystem' in interface_keys):

                 # pick values of the device

                 device_values = interfaces_and_properties[interface_keys[0]]

                 device_path = bytearray(device_values['Device'][0:-1]).decode('latin-1')

                 print('detected new device: path=\'{0}\''.format(device_path))

                 enforce_mount('/org/freedesktop/UDisks2/block_devices/' + device_path.split('/')[-1])

     def listen(self):

         """Start listening on DBus"""

         self.loop = gobject.MainLoop()

         self.loop.run()

     @dbus.service.method('at.ac.ait.opensecurity.AutoShadow')

     def Quit(self):

         """Terminate this service"""

         self.loop.quit()

     @dbus.service.method('at.ac.ait.opensecurity.AutoShadow', out_signature='s')

     def Version(self):

         """Give a version string"""

         return __version__

 def enforce_mount(udisk_object):

     """This function does the real mounting of drives. 

     It also enforces the MirrorFuse on these mounts.

     """

     print("ENFORCING mount of " + udisk_object)

 def main():             

     # parse command line

     parser = argparse.ArgumentParser(description = 'Automount USB storage devices and invoke shadowfuse for it.')

     args = parser.parse_args()

     # setup DBus event loop

     autoshadow_service = AutoShadowService()

     autoshadow_service.listen()    

 # start

 if __name__ == "__main__":

     main()