#!/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()