Viewing file:  dbus_exporter.py (7.58 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
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
|