mirror of
https://github.com/mail-in-a-box/mailinabox.git
synced 2024-11-22 02:17:26 +00:00
77 lines
2.8 KiB
Python
77 lines
2.8 KiB
Python
def load_environment():
|
|
# Load settings from /etc/mailinabox.conf.
|
|
import os.path
|
|
env = { }
|
|
for line in open("/etc/mailinabox.conf"): env.setdefault(*line.strip().split("=", 1))
|
|
env["CONF_DIR"] = os.path.join(os.path.dirname(__file__), "../conf")
|
|
return env
|
|
|
|
def exclusive_process(name):
|
|
# Ensure that a process named `name` does not execute multiple
|
|
# times concurrently.
|
|
import os, sys, atexit
|
|
pidfile = '/var/run/mailinabox-%s.pid' % name
|
|
mypid = os.getpid()
|
|
|
|
# Attempt to get a lock on ourself so that the concurrency check
|
|
# itself is not executed in parallel.
|
|
with open(__file__, 'r+') as flock:
|
|
# Try to get a lock. This blocks until a lock is acquired. The
|
|
# lock is held until the flock file is closed at the end of the
|
|
# with block.
|
|
os.lockf(flock.fileno(), os.F_LOCK, 0)
|
|
|
|
# While we have a lock, look at the pid file. First attempt
|
|
# to write our pid to a pidfile if no file already exists there.
|
|
try:
|
|
with open(pidfile, 'x') as f:
|
|
# Successfully opened a new file. Since the file is new
|
|
# there is no concurrent process. Write our pid.
|
|
f.write(str(mypid))
|
|
atexit.register(clear_my_pid, pidfile)
|
|
return
|
|
except FileExistsError:
|
|
# The pid file already exixts, but it may contain a stale
|
|
# pid of a terminated process.
|
|
with open(pidfile, 'r+') as f:
|
|
# Read the pid in the file.
|
|
existing_pid = None
|
|
try:
|
|
existing_pid = int(f.read().strip())
|
|
except ValueError:
|
|
pass # No valid integer in the file.
|
|
|
|
# Check if the pid in it is valid.
|
|
if existing_pid:
|
|
if is_pid_valid(existing_pid):
|
|
print("Another %s is already running (pid %d)." % (name, existing_pid), file=sys.stderr)
|
|
sys.exit(1)
|
|
|
|
# Write our pid.
|
|
f.seek(0)
|
|
f.write(str(mypid))
|
|
f.truncate()
|
|
atexit.register(clear_my_pid, pidfile)
|
|
|
|
|
|
def clear_my_pid(pidfile):
|
|
import os
|
|
os.unlink(pidfile)
|
|
|
|
|
|
def is_pid_valid(pid):
|
|
"""Checks whether a pid is a valid process ID of a currently running process."""
|
|
# adapted from http://stackoverflow.com/questions/568271/how-to-check-if-there-exists-a-process-with-a-given-pid
|
|
import os, errno
|
|
if pid <= 0: raise ValueError('Invalid PID.')
|
|
try:
|
|
os.kill(pid, 0)
|
|
except OSError as err:
|
|
if err.errno == errno.ESRCH: # No such process
|
|
return False
|
|
elif err.errno == errno.EPERM: # Not permitted to send signal
|
|
return True
|
|
else: # EINVAL
|
|
raise
|
|
else:
|
|
return True |