core, bridge, jp, quick_frontend: SàT stop more gracefully if bridge can't be initialised:

- new BridgeInitError and BridgeExceptionNoService are in core.exceptions
    - D-Bus NotSupported is catched in bridge, and launch a BridgeInitError
    - BridgeInitError stop SàT core, jp, and quick_frontends with an explanation message.
fix bug 27

src/bridge/bridge_constructor/dbus_core_template.py

@@ -24,6 +24,7 @@ import dbus.mainloop.glib
 import inspect
 from logging import debug, info, error
 from twisted.internet.defer import Deferred
+from sat.core.exceptions import BridgeInitError
 
 const_INT_PREFIX = "org.goffi.SAT"  # Interface prefix
 const_ERROR_PREFIX = const_INT_PREFIX + ".error"
@@ -204,7 +205,12 @@ class DBusBridge(Bridge):
         dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
         Bridge.__init__(self)
         info("Init DBus...")
-        self.session_bus = dbus.SessionBus()
+        try:
+            self.session_bus = dbus.SessionBus()
+        except dbus.DBusException as e:
+            if e._dbus_error_name == 'org.freedesktop.DBus.Error.NotSupported':
+                print u"D-Bus is not launched, please see README to see instructions on how to launch it"
+            raise BridgeInitError
         self.dbus_name = dbus.service.BusName(const_INT_PREFIX, self.session_bus)
         self.dbus_bridge = DbusObject(self.session_bus, const_OBJ_PATH)
 

src/bridge/bridge_constructor/dbus_frontend_template.py

@@ -20,6 +20,7 @@
 from bridge_frontend import BridgeFrontend
 import dbus
 from logging import debug, error
+from sat.core.exceptions import BridgeExceptionNoService, BridgeInitError
 
 from dbus.mainloop.glib import DBusGMainLoop
 DBusGMainLoop(set_as_default=True)
@@ -31,10 +32,6 @@ const_CORE_SUFFIX = ".core"
 const_PLUGIN_SUFFIX = ".plugin"
 
 
-class BridgeExceptionNoService(Exception):
-    pass
-
-
 class DBusBridgeFrontend(BridgeFrontend):
     def __init__(self):
         try:
@@ -48,6 +45,9 @@ class DBusBridgeFrontend(BridgeFrontend):
         except dbus.exceptions.DBusException, e:
             if e._dbus_error_name == 'org.freedesktop.DBus.Error.ServiceUnknown':
                 raise BridgeExceptionNoService
+            elif e._dbus_error_name == 'org.freedesktop.DBus.Error.NotSupported':
+                print u"D-Bus is not launched, please see README to see instructions on how to launch it"
+                raise BridgeInitError
             else:
                 raise e
         #props = self.db_core_iface.getProperties()