root/branches/gajim_0.10/src/dbus_support.py

##  dbus_support.py
##
## Copyright (C) 2005 Yann Le Boulanger <asterix@lagaule.org>
## Copyright (C) 2005 Nikos Kouremenos <kourem@gmail.com>
## Copyright (C) 2005 Dimitur Kirov <dkirov@gmail.com>
## Copyright (C) 2005 Andrew Sayman <lorien420@myrealbox.com>
##
## 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 only.
##
## 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.
##

import os
import sys

from common import gajim
from common import exceptions
from common import i18n
_ = i18n._

try:
        import dbus
        version = getattr(dbus, 'version', (0, 20, 0))
        supported = True
except ImportError:
        version = (0, 0, 0)
        supported = False
        if not os.name == 'nt': # only say that to non Windows users
                print _('D-Bus python bindings are missing in this computer')
                print _('D-Bus capabilities of Gajim cannot be used')
        
# dbus 0.23 leads to segfault with threads_init()
if sys.version[:4] >= '2.4' and version[1] < 30:
        supported = False

if version >= (0, 41, 0):
        import dbus.service
        import dbus.glib # cause dbus 0.35+ doesn't return signal replies without it

class SessionBus:
        '''A Singleton for the DBus SessionBus'''
        def __init__(self):
                self.session_bus = None
        
        def SessionBus(self):
                if not supported:
                        raise exceptions.DbusNotSupported

                if not self.present():
                                raise exceptions.SessionBusNotPresent
                return self.session_bus

        def bus(self):
                return self.SessionBus()

        def present(self):
                if not supported:
                        return False
                if self.session_bus is None:
                        try:
                                self.session_bus = dbus.SessionBus()
                        except dbus.dbus_bindings.DBusException:
                                self.session_bus = None
                                return False
                        if self.session_bus is None:
                                return False
                return True

session_bus = SessionBus()

def get_interface(interface, path):
        '''Returns an interface on the current SessionBus. If the interface isn't 
        running, it tries to start it first.'''
        if not supported:
                return None
        if session_bus.present():
                bus = session_bus.SessionBus()
        else:
                return None
        try:
                obj = bus.get_object('org.freedesktop.DBus', '/org/freedesktop/DBus')
                dbus_iface = dbus.Interface(obj, 'org.freedesktop.DBus')
                running_services = dbus_iface.ListNames()
                started = True
                if interface not in running_services:
                        # try to start the service
                        if dbus_iface.StartServiceByName(interface, dbus.UInt32(0)) == 1:
                                started = True
                        else:
                                started = False
                if not started:
                        return None
                obj = bus.get_object(interface, path)
                return dbus.Interface(obj, interface)
        except Exception, e:
                gajim.log.debug(str(e))
                return None


def get_notifications_interface():
        '''Returns the notifications interface.'''
        return get_interface('org.freedesktop.Notifications','/org/freedesktop/Notifications')