gajim-plural/gajim/common/dbus_support.py

# Copyright (C) 2005 Andrew Sayman <lorien420 AT myrealbox.com>
#                    Dimitur Kirov <dkirov AT gmail.com>
# Copyright (C) 2005-2006 Nikos Kouremenos <kourem AT gmail.com>
# Copyright (C) 2005-2014 Yann Leboulanger <asterix AT lagaule.org>
# Copyright (C) 2006 Jean-Marie Traissard <jim AT lapin.org>
#                    Stefan Bethge <stefan AT lanpartei.de>
# Copyright (C) 2008 Jonathan Schleifer <js-gajim AT webkeks.org>
#
# This file is part of Gajim.
#
# Gajim 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 3 only.
#
# Gajim 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 Gajim. If not, see <http://www.gnu.org/licenses/>.

import sys
import logging

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

_GAJIM_ERROR_IFACE = 'org.gajim.dbus.Error'

log = logging.getLogger('gajim.c.dbus')

try:
    import dbus
    from dbus.mainloop.glib import DBusGMainLoop
    DBusGMainLoop(set_as_default=True)
except ImportError:
    supported = False
    if sys.platform == 'linux':  # windows and mac have no dbus
        print(_('D-Bus python bindings are missing in this computer'))
        print(_('D-Bus capabilities of Gajim cannot be used'))
else:
    try:
        # test if dbus-x11 is installed
        _bus = dbus.SystemBus()
        _bus = dbus.SessionBus()
        supported = True # does user have D-Bus bindings?
    except dbus.DBusException:
        supported = False
        if sys.platform == 'linux':  # windows and mac have no dbus
            print(_('D-Bus does not run correctly on this machine'))
            print(_('D-Bus capabilities of Gajim cannot be used'))
    except exceptions.SystemBusNotPresent:
        print(_('D-Bus does not run correctly on this machine: system bus not '
            'present'))
    except exceptions.SessionBusNotPresent:
        print(_('D-Bus does not run correctly on this machine: session bus not '
            'present'))

class SystemBus:
    """
    A Singleton for the DBus SystemBus
    """

    def __init__(self):
        self.system_bus = None

    def SystemBus(self):
        if not supported:
            raise exceptions.DbusNotSupported

        if not self.present():
            raise exceptions.SystemBusNotPresent
        return self.system_bus

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

    def present(self):
        if not supported:
            return False
        if self.system_bus is None:
            try:
                self.system_bus = dbus.SystemBus()
            except dbus.DBusException:
                self.system_bus = None
                return False
            if self.system_bus is None:
                return False
            # Don't exit Gajim when dbus is stopped
            self.system_bus.set_exit_on_disconnect(False)
        return True

system_bus = SystemBus()

class SessionBus:
    """
    A Singleton for the D-Bus 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.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, start_service=True):
    """
    Get an interface on the current SessionBus. If the interface isn't running,
    try 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
            started = start_service and dbus_iface.StartServiceByName(
                interface, dbus.UInt32(0)) == 1
        if not started:
            return None
        obj = bus.get_object(interface, path)
        return dbus.Interface(obj, interface)
    except Exception as error:
        log.debug(error)
        return None


if supported:
    class MissingArgument(dbus.DBusException):
        _dbus_error_name = _GAJIM_ERROR_IFACE + '.MissingArgument'

    class InvalidArgument(dbus.DBusException):
        '''Raised when one of the provided arguments is invalid.'''
        _dbus_error_name = _GAJIM_ERROR_IFACE + '.InvalidArgument'