blob: 21487693595db4831ebdb61d603c9f656038d99d [file] [log] [blame]
# Copyright (c) 2011-2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import os
import sys
import errno
import signal
import subprocess
import cros_build_lib
class SudoKeepAlive(cros_build_lib.MasterPidContextManager):
This refreshes the sudo auth cookie; this is implemented this
way to ensure that sudo has access to both invoking tty, and
will update the user's tty-less cookie.
see crosbug/18393.
def __init__(self, repeat_interval=4):
"""Run sudo with a noop, to reset the sudo timestamp.
repeat_interval: In minutes, the frequency to run the update.
self._repeat_interval = repeat_interval
self._proc = None
def _IdentifyTTY():
for source in (sys.stdin, sys.stdout, sys.stderr):
return os.ttyname(source.fileno())
except EnvironmentError, e:
if e.errno not in (errno.EINVAL, errno.ENOTTY):
return 'unknown'
def _DaemonNeeded(self):
Discern if we need to run the sudo keep alive code.
None if the daemon isn't needed, else the string of the pts needed.
existing = os.environ.get("CROS_SUDO_KEEP_ALIVE")
tty = self._IdentifyTTY()
if existing is None:
return tty
elif tty == existing:
# Same auth ticket as our parent; we can use it.
return None
elif tty == 'unknown':
# The existing instance still covers us, despite us being bound to no pts.
return None
# Reaching here means that somehow, we're on a literal different pts than
# the original. This requires a daemon.
return tty
def _enter(self):
start_for_tty = self._DaemonNeeded()
if start_for_tty is None or os.getuid() == 0:
# We're root; we don't need the sudo keep alive hack.
# Note despite the impulse to use 'sudo -v' instead of 'sudo true', the
# builder's sudoers configuration is slightly whacked resulting in it
# asking for password everytime. As such use 'sudo true' instead.
# First check to see if we're already authed. If so, then we don't
# need to prompt the user for their password.
ret = cros_build_lib.RunCommand(
'sudo -n true 2> /dev/null && ' +
'sudo -n true < /dev/null > /dev/null 2>&1',
print_cmd=False, shell=True, error_code_ok=True)
if ret.returncode != 0:
# We need to go interactive and allow sudo to ask for credentials.
cros_build_lib.Info('Launching sudo keepalive process. '
'This may ask for your password twice.')
'sudo true; sudo true < /dev/null > /dev/null 2>&1',
shell=True, print_cmd=False)
repeat_interval = self._repeat_interval * 60
cmd = 'sudo -n true && sudo -n true < /dev/null > /dev/null 2>&1'
# Anything other than a timeout results in us shutting down.
cmd = ('while :; do read -t %i; [ $? -le 128 ] && exit; %s; done' %
(repeat_interval, cmd))
def ignore_sigint():
# We don't want our sudo process shutdown till we shut it down;
# since it's part of the session group it however gets SIGINT.
# Thus suppress it (which bash then inherits).
signal.signal(signal.SIGINT, signal.SIG_IGN)
self._proc = subprocess.Popen(['bash', '-c', cmd], shell=False,
close_fds=True, preexec_fn=ignore_sigint,
os.environ["CROS_SUDO_KEEP_ALIVE"] = start_for_tty
# pylint: disable=W0613
def _exit(self, exc_type, exc_value, traceback):
if self._proc is None:
except EnvironmentError, e:
if e.errno != errno.ESRCH:
os.environ.pop("CROS_SUDO_KEEP_ALIVE", None)
def SetFileContents(path, value):
"""Set a given filepath contents w/ the passed in value."""
cros_build_lib.SudoRunCommand(['tee', path], redirect_stdout=True,
print_cmd=False, input=value)