name : dbus_exporter.py from . import interfaces import dbus.service import dbus.mainloop.glib import dbus.exceptions import threading import signal import tuned.logs import tuned.consts as consts import traceback import logging from inspect import ismethod from tuned.utils.polkit import polkit from gi.repository import GLib from types import FunctionType from dbus.exceptions import DBusException from dbus.lowlevel import ErrorMessage try: # Python3 version # getfullargspec is not present in Python2, so when we drop P2 support # replace "getargspec(func)" in code with "getfullargspec(func).args" from inspect import getfullargspec def getargspec(func): return getfullargspec(func) except ImportError: # Python2 version, drop after support stops from inspect import getargspec log = tuned.logs.get() # This is mostly copy of the code from the dbus.service module without the # code that sends tracebacks through the D-Bus (i.e. no library tracebacks # are exposed on the D-Bus now). def _method_reply_error(connection, message, exception): name = getattr(exception, '_dbus_error_name', None) if name is not None: pass elif getattr(exception, '__module__', '') in ('', '__main__'): name = 'org.freedesktop.DBus.Python.%s' % exception.__class__.__name__ else: name = 'org.freedesktop.DBus.Python.%s.%s' % (exception.__module__, exception.__class__.__name__) if isinstance(exception, DBusException): contents = exception.get_dbus_message() else: contents = ''.join(traceback.format_exception_only(exception.__class__, exception)) reply = ErrorMessage(message, name, contents) if not message.get_no_reply(): connection.send_message(reply) class DBusExporter(interfaces.ExporterInterface): """ Export method calls through DBus Interface. We take a method to be exported and create a simple wrapper function to call it. This is required as we need the original function to be bound to the original object instance. While the wrapper will be bound to an object we dynamically construct. """ def __init__(self, bus_name, interface_name, object_name, namespace): # Monkey patching of the D-Bus library _method_reply_error() to reply # tracebacks via D-Bus only if in the debug mode. It doesn't seem there is a # more simple way how to cover all possible exceptions that could occur in # the D-Bus library. Just setting the exception.include_traceback to False doesn't # seem to help because there is only a subset of exceptions that support this flag. if log.getEffectiveLevel() != logging.DEBUG: dbus.service._method_reply_error = _method_reply_error dbus.mainloop.glib.DBusGMainLoop(set_as_default=True) self._dbus_object_cls = None self._dbus_object = None self._dbus_methods = {} self._signals = set() self._bus_name = bus_name self._interface_name = interface_name self._object_name = object_name self._namespace = namespace self._thread = None self._bus_object = None self._polkit = polkit() # dirty hack that fixes KeyboardInterrupt handling # the hack is needed because PyGObject / GTK+-3 developers are morons signal_handler = signal.getsignal(signal.SIGINT) self._main_loop = GLib.MainLoop() signal.signal(signal.SIGINT, signal_handler) @property def bus_name(self): return self._bus_name @property def interface_name(self): return self._interface_name @property def object_name(self): return self._object_name def running(self): return self._thread is not None def _prepare_for_dbus(self, method, wrapper): source = """def {name}({args}): return wrapper({args}) """.format(name=method.__name__, args=', '.join(getargspec(method.__func__).args)) code = compile(source, '<decorator-gen-%d>' % len(self._dbus_methods), 'exec') # https://docs.python.org/3.9/library/inspect.html # co_consts - tuple of constants used in the bytecode # example: # compile("e=2\ndef f(x):\n return x*2\n", "X", 'exec').co_consts # (2, <code object f at 0x7f8c60c65330, file "X", line 2>, None) # Because we have only one object in code (our function), we can use code.co_consts[0] func = FunctionType(code.co_consts[0], locals(), method.__name__) return func def export(self, method, in_signature, out_signature): if not ismethod(method): raise Exception("Only bound methods can be exported.") method_name = method.__name__ if method_name in self._dbus_methods: raise Exception("Method with this name is already exported.") def wrapper(owner, *args, **kwargs): action_id = self._namespace + "." + method.__name__ caller = args[-1] log.debug("checking authorization for action '%s' requested by caller '%s'" % (action_id, caller)) ret = self._polkit.check_authorization(caller, action_id) args_copy = args if ret == 1: log.debug("action '%s' requested by caller '%s' was successfully authorized by polkit" % (action_id, caller)) elif ret == 2: log.warn("polkit error, but action '%s' requested by caller '%s' was successfully authorized by fallback method" % (action_id, caller)) elif ret == 0: log.info("action '%s' requested by caller '%s' wasn't authorized, ignoring the request" % (action_id, caller)) args_copy = list(args[:-1]) + [""] elif ret == -1: log.warn("polkit error and action '%s' requested by caller '%s' wasn't authorized by fallback method, ignoring the request" % (action_id, caller)) args_copy = list(args[:-1]) + [""] else: log.error("polkit error and unable to use fallback method to authorize action '%s' requested by caller '%s', ignoring the request" % (action_id, caller)) args_copy = list(args[:-1]) + [""] return method(*args_copy, **kwargs) wrapper = self._prepare_for_dbus(method, wrapper) wrapper = dbus.service.method(self._interface_name, in_signature, out_signature, sender_keyword = "caller")(wrapper) self._dbus_methods[method_name] = wrapper def signal(self, method, out_signature): if not ismethod(method): raise Exception("Only bound methods can be exported.") method_name = method.__name__ if method_name in self._dbus_methods: raise Exception("Method with this name is already exported.") def wrapper(owner, *args, **kwargs): return method(*args, **kwargs) wrapper = self._prepare_for_dbus(method, wrapper) wrapper = dbus.service.signal(self._interface_name, out_signature)(wrapper) self._dbus_methods[method_name] = wrapper self._signals.add(method_name) def send_signal(self, signal, *args, **kwargs): err = False if not signal in self._signals or self._bus_object is None: err = True try: method = getattr(self._bus_object, signal) except AttributeError: err = True if err: raise Exception("Signal '%s' doesn't exist." % signal) else: method(*args, **kwargs) def _construct_dbus_object_class(self): if self._dbus_object_cls is not None: raise Exception("The exporter class was already build.") unique_name = "DBusExporter_%d" % id(self) cls = type(unique_name, (dbus.service.Object,), self._dbus_methods) self._dbus_object_cls = cls def start(self): if self.running(): return if self._dbus_object_cls is None: self._construct_dbus_object_class() self.stop() bus = dbus.SystemBus() bus_name = dbus.service.BusName(self._bus_name, bus) self._bus_object = self._dbus_object_cls(bus, self._object_name, bus_name) self._thread = threading.Thread(target=self._thread_code) self._thread.start() def stop(self): if self._thread is not None and self._thread.is_alive(): self._main_loop.quit() self._thread.join() self._thread = None def _thread_code(self): self._main_loop.run() del self._bus_object self._bus_object = None