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-rw-r--r--src/leap/platform_init/locks.py405
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diff --git a/src/leap/platform_init/locks.py b/src/leap/platform_init/locks.py
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--- a/src/leap/platform_init/locks.py
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-# -*- coding: utf-8 -*-
-# locks.py
-# Copyright (C) 2013 LEAP
-#
-# 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 3 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, see <http://www.gnu.org/licenses/>.
-"""
-Utilities for handling multi-platform file locking mechanisms
-"""
-import logging
-import errno
-import os
-import platform
-
-from leap.common.events import signal as signal_event
-from leap.common.events import events_pb2 as proto
-from leap import platform_init
-
-if platform_init.IS_UNIX:
- from fcntl import flock, LOCK_EX, LOCK_NB
-else: # WINDOWS
- import datetime
- import glob
- import shutil
- import time
-
- from tempfile import gettempdir
-
- from leap.util import get_modification_ts, update_modification_ts
-
-logger = logging.getLogger(__name__)
-
-if platform_init.IS_UNIX:
-
- class UnixLock(object):
- """
- Uses flock to get an exclusive lock over a file.
- See man 2 flock
- """
-
- def __init__(self, path):
- """
- iniializes t he UnixLock with the path of the
- desired lockfile
- """
-
- self._fd = None
- self.path = path
-
- def get_lock(self):
- """
- Tries to get a lock, and writes the running pid there if successful
- """
- gotit, pid = self._get_lock_and_pid()
- return gotit
-
- def get_pid(self):
- """
- Returns the pid of the locking process
- """
- gotit, pid = self._get_lock_and_pid()
- return pid
-
- def _get_lock(self):
- """
- Tries to get a lock, returning True if successful
-
- :rtype: bool
- """
- self._fd = os.open(self.path, os.O_CREAT | os.O_RDWR)
-
- try:
- flock(self._fd, LOCK_EX | LOCK_NB)
- except IOError as exc:
- # could not get the lock
- #import ipdb; ipdb.set_trace()
-
- if exc.args[0] in (errno.EDEADLK, errno.EAGAIN):
- # errno 11 or 35
- # Resource temporarily unavailable
- return False
- else:
- raise
- return True
-
- @property
- def locked_by_us(self):
- """
- Returns True if the pid in the pidfile
- is ours.
-
- :rtype: bool
- """
- gotit, pid = self._get_lock_and_pid()
- return pid == os.getpid()
-
- def _get_lock_and_pid(self):
- """
- Tries to get a lock over the file.
- Returns (locked, pid) tuple.
-
- :rtype: tuple
- """
-
- if self._get_lock():
- self._write_to_pidfile()
- return True, None
-
- return False, self._read_from_pidfile()
-
- def _read_from_pidfile(self):
- """
- Tries to read pid from the pidfile,
- returns False if no content found.
- """
-
- pidfile = os.read(
- self._fd, 16)
- if not pidfile:
- return False
-
- try:
- return int(pidfile.strip())
- except Exception as exc:
- exc.args += (pidfile, self.lock_file)
- raise
-
- def _write_to_pidfile(self):
- """
- Writes the pid of the running process
- to the pidfile
- """
- fd = self._fd
- os.ftruncate(fd, 0)
- os.write(fd, '%d\n' % os.getpid())
- os.fsync(fd)
-
-
-if platform_init.IS_WIN:
-
- # Time to wait (in secs) before assuming a raise window signal has not been
- # ack-ed.
-
- RAISE_WINDOW_TIMEOUT = 2
-
- # How many steps to do while checking lockfile ts update.
-
- RAISE_WINDOW_WAIT_STEPS = 10
-
- def _release_lock(name):
- """
- Tries to remove a folder path.
-
- :param name: folder lock to remove
- :type name: str
- """
- try:
- shutil.rmtree(name)
- return True
- except WindowsError as exc:
- if exc.errno in (errno.EPIPE, errno.ENOENT,
- errno.ESRCH, errno.EACCES):
- logger.warning(
- 'exception while trying to remove the lockfile dir')
- logger.warning('errno %s: %s' % (exc.errno, exc.args[1]))
- # path does not exist
- return False
- else:
- logger.debug('errno = %s' % (exc.errno,))
- # we did not foresee this error, better add it explicitely
- raise
-
- class WindowsLock(object):
- """
- Creates a lock based on the atomic nature of mkdir on Windows
- system calls.
- """
- LOCKBASE = os.path.join(gettempdir(), "leap-client-lock")
-
- def __init__(self):
- """
- Initializes the lock.
- Sets the lock name to basename plus the process pid.
- """
- self._fd = None
- pid = os.getpid()
- self.name = "%s-%s" % (self.LOCKBASE, pid)
- self.pid = pid
-
- def get_lock(self):
- """
- Tries to get a lock, and writes the running pid there if successful
- """
- gotit = self._get_lock()
- return gotit
-
- def _get_lock(self):
- """
- Tries to write to a file with the current pid as part of the name
- """
- try:
- self._fd = os.makedirs(self.name)
- except OSError as exc:
- # could not create the dir
- if exc.args[0] == 183:
- logger.debug('cannot create dir')
- # cannot create dir with existing name
- return False
- else:
- raise
- return self._is_one_pidfile()[0]
-
- def _is_one_pidfile(self):
- """
- Returns True, pid if there is only one pidfile with the expected
- base path
-
- :rtype: tuple
- """
- pidfiles = glob.glob(self.LOCKBASE + '-*')
- if len(pidfiles) == 1:
- pid = pidfiles[0].split('-')[-1]
- return True, int(pid)
- else:
- return False, None
-
- def get_pid(self):
- """
- Returns the pid of the locking process.
-
- :rtype: int
- """
- # XXX assert there is only one?
- _, pid = self._is_one_pidfile()
- return pid
-
- def get_locking_path(self):
- """
- Returns the pid path of the locking process.
-
- :rtype: str
- """
- pid = self.get_pid()
- if pid:
- return "%s-%s" % (self.LOCKBASE, pid)
-
- def release_lock(self, name=None):
- """
- Releases the pidfile dir for this process, by removing it.
- """
- if not name:
- name = self.name
- _release_lock(name)
-
- @classmethod
- def release_all_locks(self):
- """
- Releases all locks. Used for clean shutdown.
- """
- for lockdir in glob.glob("%s-%s" % (self.LOCKBASE, '*')):
- _release_lock(lockdir)
-
- @property
- def locked_by_us(self):
- """
- Returns True if the pid in the pidfile
- is ours.
-
- :rtype: bool
- """
- _, pid = self._is_one_pidfile()
- return pid == self.pid
-
- def update_ts(self):
- """
- Updates the timestamp of the lock.
- """
- if self.locked_by_us:
- update_modification_ts(self.name)
-
- def write_port(self, port):
- """
- Writes the port for windows control to the pidfile folder
- Returns True if successful.
-
- :rtype: bool
- """
- if not self.locked_by_us:
- logger.warning("Tried to write control port to a "
- "non-unique pidfile folder")
- return False
- port_file = os.path.join(self.name, "port")
- with open(port_file, 'w') as f:
- f.write("%s" % port)
- return True
-
- def get_control_port(self):
- """
- Reads control port of the main instance from the port file
- in the pidfile dir
-
- :rtype: int
- """
- pid = self.get_pid()
- port_file = os.path.join(self.LOCKBASE + "-%s" % pid, "port")
- port = None
- try:
- with open(port_file) as f:
- port_str = f.read()
- port = int(port_str.strip())
- except IOError as exc:
- if exc.errno == errno.ENOENT:
- logger.error("Tried to read port from non-existent file")
- else:
- # we did not know explicitely about this error
- raise
- return port
-
- def raise_window_ack():
- """
- This function is called from the windows callback that is registered
- with the raise_window event. It just updates the modification time
- of the lock file so we can signal an ack to the instance that tried
- to raise the window.
- """
- lock = WindowsLock()
- lock.update_ts()
-
-
-def we_are_the_one_and_only():
- """
- Returns True if we are the only instance running, False otherwise.
- If we came later, send a raise signal to the main instance of the
- application.
-
- Under windows we are not using flock magic, so we wait during
- RAISE_WINDOW_TIMEOUT time, if not ack is
- received, we assume it was a stalled lock, so we remove it and continue
- with initialization.
-
- :rtype: bool
- """
- _sys = platform.system()
-
- if _sys in ("Linux", "Darwin"):
- locker = UnixLock('/tmp/leap-client.lock')
- locker.get_lock()
- we_are_the_one = locker.locked_by_us
- if not we_are_the_one:
- signal_event(proto.RAISE_WINDOW)
- return we_are_the_one
-
- elif _sys == "Windows":
- locker = WindowsLock()
- locker.get_lock()
- we_are_the_one = locker.locked_by_us
-
- if not we_are_the_one:
- locker.release_lock()
- lock_path = locker.get_locking_path()
- ts = get_modification_ts(lock_path)
-
- nowfun = datetime.datetime.now
- t0 = nowfun()
- pause = RAISE_WINDOW_TIMEOUT / float(RAISE_WINDOW_WAIT_STEPS)
- timeout_delta = datetime.timedelta(0, RAISE_WINDOW_TIMEOUT)
- check_interval = lambda: nowfun() - t0 < timeout_delta
-
- # let's assume it's a stalled lock
- we_are_the_one = True
- signal_event(proto.RAISE_WINDOW)
-
- while check_interval():
- if get_modification_ts(lock_path) > ts:
- # yay! someone claimed their control over the lock.
- # so the lock is alive
- logger.debug('Raise window ACK-ed')
- we_are_the_one = False
- break
- else:
- time.sleep(pause)
-
- if we_are_the_one:
- # ok, it really was a stalled lock. let's remove all
- # that is left, and put only ours there.
- WindowsLock.release_all_locks()
- WindowsLock().get_lock()
-
- return we_are_the_one
-
- else:
- logger.warning("Multi-instance checker "
- "not implemented for %s" % (_sys))
- # lies, lies, lies...
- return True