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diff --git a/src/leap/bitmask/platform_init/locks.py b/src/leap/bitmask/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
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