mailinabox/management/utils.py

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2014-06-03 20:21:17 +00:00
def load_environment():
# Load settings from /etc/mailinabox.conf.
import os.path
env = load_env_vars_from_file("/etc/mailinabox.conf")
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env["CONF_DIR"] = os.path.join(os.path.dirname(__file__), "../conf")
return env
def load_env_vars_from_file(fn):
# Load settings from a KEY=VALUE file.
env = { }
for line in open(fn): env.setdefault(*line.strip().split("=", 1))
return env
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def safe_domain_name(name):
# Sanitize a domain name so it is safe to use as a file name on disk.
import urllib.parse
return urllib.parse.quote(name, safe='')
def sort_domains(domain_names, env):
# Put domain names in a nice sorted order. For web_update, PUBLIC_HOSTNAME
# must appear first so it becomes the nginx default server.
# First group PUBLIC_HOSTNAME and its subdomains, then parent domains of PUBLIC_HOSTNAME, then other domains.
groups = ( [], [], [] )
for d in domain_names:
if d == env['PUBLIC_HOSTNAME'] or d.endswith("." + env['PUBLIC_HOSTNAME']):
groups[0].append(d)
elif env['PUBLIC_HOSTNAME'].endswith("." + d):
groups[1].append(d)
else:
groups[2].append(d)
# Within each group, sort parent domains before subdomains and after that sort lexicographically.
def sort_group(group):
# Find the top-most domains.
top_domains = sorted(d for d in group if len([s for s in group if s.startswith("." + d)]) == 0)
ret = []
for d in top_domains:
ret.append(d)
ret.extend( sort_group([s for s in group if s.endswith("." + d)]) )
return ret
groups = [sort_group(g) for g in groups]
return groups[0] + groups[1] + groups[2]
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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
def shell(method, cmd_args, env={}, capture_stderr=False, return_bytes=False, trap=False, input=None):
# A safe way to execute processes.
# Some processes like apt-get require being given a sane PATH.
import subprocess
env.update({ "PATH": "/sbin:/bin:/usr/sbin:/usr/bin" })
kwargs = {
'env': env,
'stderr': None if not capture_stderr else subprocess.STDOUT,
}
if method == "check_output" and input is not None:
kwargs['input'] = input
if not trap:
ret = getattr(subprocess, method)(cmd_args, **kwargs)
else:
try:
ret = getattr(subprocess, method)(cmd_args, **kwargs)
code = 0
except subprocess.CalledProcessError as e:
ret = e.output
code = e.returncode
if not return_bytes and isinstance(ret, bytes): ret = ret.decode("utf8")
if not trap:
return ret
else:
return code, ret
def create_syslog_handler():
import logging.handlers
handler = logging.handlers.SysLogHandler(address='/dev/log')
handler.setLevel(logging.WARNING)
return handler