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# Copyright (C) 2018,2019, Sam Thursfield <sam@afuera.me.uk>
#
# 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; either version 2
# of the License, or (at your option) any later version.
#
# 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.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.
from gi.repository import Gio
from gi.repository import GLib
import logging
import os
import shutil
import signal
import subprocess
import threading
log = logging.getLogger(__name__)
dbus_stderr_log = logging.getLogger(__name__ + '.stderr')
dbus_stdout_log = logging.getLogger(__name__ + '.stdout')
class DaemonNotStartedError(Exception):
pass
class DBusDaemon:
"""The private D-Bus instance that provides the sandbox's session bus."""
def __init__(self):
self.process = None
self.address = None
self.pid = None
self._gdbus_connection = None
self._previous_sigterm_handler = None
self._threads = []
def get_address(self):
if self.address is None:
raise DaemonNotStartedError()
return self.address
def create_connection(self):
"""Creates a new GDBusConnection."""
if self.address is None:
raise DaemonNotStartedError()
return Gio.DBusConnection.new_for_address_sync(
self.address,
Gio.DBusConnectionFlags.AUTHENTICATION_CLIENT |
Gio.DBusConnectionFlags.MESSAGE_BUS_CONNECTION, None, None)
def get_connection(self):
"""Returns a shared GDBusConnection for general use."""
if self._gdbus_connection is None:
raise DaemonNotStartedError()
return self._gdbus_connection
def _dbus_daemon_path(self):
dbus_daemon = shutil.which('dbus-daemon')
if dbus_daemon is None:
raise RuntimeError("Could not find `dbus-daemon` binary in PATH (%s)." % os.environ.get('PATH'))
return dbus_daemon
def start(self, config_file=None, env=None, new_session=False):
dbus_command = [self._dbus_daemon_path(), '--print-address=1', '--print-pid=1']
if config_file:
dbus_command += ['--config-file=' + config_file]
else:
dbus_command += ['--session']
log.debug("Running: %s", dbus_command)
self.process = subprocess.Popen(
dbus_command, env=env, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
start_new_session=new_session)
self._previous_sigterm_handler = signal.signal(
signal.SIGTERM, self._sigterm_handler)
try:
self.address = self.process.stdout.readline().strip().decode('ascii')
self.pid = int(self.process.stdout.readline().strip().decode('ascii'))
except ValueError:
error = self.process.stderr.read().strip().decode('unicode-escape')
raise RuntimeError(f"Failed to start D-Bus daemon.\n{error}")
log.debug("Using new D-Bus session with address '%s' with PID %d",
self.address, self.pid)
# We must read from the pipes continuously, otherwise the daemon
# process will block.
self._threads=[threading.Thread(target=self.pipe_to_log, args=(self.process.stdout, dbus_stdout_log), daemon=True),
threading.Thread(target=self.pipe_to_log, args=(self.process.stderr, dbus_stdout_log), daemon=True)]
self._threads[0].start()
self._threads[1].start()
self._gdbus_connection = self.create_connection()
log.debug("Pinging the new D-Bus daemon...")
self.ping_sync()
def stop(self):
if self.process:
log.debug(" Stopping DBus daemon")
self.process.terminate()
self.process.wait()
self.process = None
if len(self._threads) > 0:
log.debug(" Stopping %i pipe reader threads", len(self._threads))
for thread in self._threads:
thread.join()
self.threads = []
if self._previous_sigterm_handler:
signal.signal(signal.SIGTERM, self._previous_sigterm_handler)
self._previous_sigterm_handler = None
log.debug("DBus daemon stopped")
def pipe_to_log(self, pipe, dbuslog):
"""This function processes the output from our dbus-daemon instance."""
while True:
line_raw = pipe.readline()
if len(line_raw) == 0:
break
line = line_raw.decode('utf-8').rstrip()
if line.startswith('(tracker-'):
# We set G_MESSAGES_PREFIXED=all, meaning that all log messages
# output by Tracker processes have a prefix. Note that
# g_print() will NOT be captured here.
dbuslog.info(line)
else:
# Log messages from other daemons, including the dbus-daemon
# itself, go here. Any g_print() messages also end up here.
dbuslog.debug(line)
log.debug("Thread stopped")
# I'm not sure why this is needed, or if it's correct, but without it
# we see warnings like this:
#
# ResourceWarning: unclosed file <_io.BufferedReader name=3>
pipe.close()
def _sigterm_handler(self, signal, frame):
log.info("Received signal %s", signal)
self.stop()
def ping_sync(self):
"""Call the daemon Ping() method to check that it is alive."""
self._gdbus_connection.call_sync(
'org.freedesktop.DBus', '/', 'org.freedesktop.DBus', 'GetId',
None, None, Gio.DBusCallFlags.NONE, 10000, None)
def list_names_sync(self):
"""Get the name of every client connected to the bus."""
conn = self.get_connection()
result = conn.call_sync('org.freedesktop.DBus',
'/org/freedesktop/DBus',
'org.freedesktop.DBus', 'ListNames', None,
GLib.VariantType('(as)'),
Gio.DBusCallFlags.NONE, -1, None)
return result[0]
def get_connection_unix_process_id_sync(self, name):
"""Get the process ID for one of the names connected to the bus."""
conn = self.get_connection()
result = conn.call_sync('org.freedesktop.DBus',
'/org/freedesktop/DBus',
'org.freedesktop.DBus',
'GetConnectionUnixProcessID',
GLib.Variant('(s)', [name]),
GLib.VariantType('(u)'),
Gio.DBusCallFlags.NONE, -1, None)
return result[0]
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