# No shebang line, this module is meant to be imported
#
# Copyright 2014 Oliver Palmer
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Utility
=======
Small objects and functions which facilitate operations
on the main entry point class.
"""
import os
import sys
try:
from os import setuid, setgid, fork
except ImportError: # pragma: no cover
setuid = NotImplemented
setgid = NotImplemented
fork = NotImplemented
from pyfarm.core.enums import OS
from pyfarm.agent.logger import getLogger
logger = getLogger("agent.cmd")
# This is a Linux specific test and will be hard to get due to the nature
# of how the tests are run, for now we're excluding it.
# TODO: figure out a reliable way to test start_daemon_posix
[docs]def start_daemon_posix(log, chdir, uid, gid): # pragma: no cover
"""
Runs the agent process via a double fork. This basically a duplicate
of Marcechal's original code with some adjustments:
http://www.jejik.com/articles/2007/02/
a_simple_unix_linux_daemon_in_python/
Source files from his post are here:
http://www.jejik.com/files/examples/daemon.py
http://www.jejik.com/files/examples/daemon3x.py
"""
# first fork
try:
pid = fork()
if pid > 0:
sys.exit(0)
except OSError as e:
logger.error(
"fork 1 failed (errno: %s): %s" % (e.errno, e.strerror))
return 1
# decouple from the parent environment
os.chdir(chdir or "/")
os.setsid()
os.umask(0)
# second fork
try:
pid = fork()
if pid > 0:
sys.exit(0)
except OSError as e:
logger.error(
"fork 2 failed (errno: %s): %s" % (e.errno, e.strerror))
return 1
# flush any pending data before we duplicate
# the file descriptors
sys.stdout.flush()
sys.stderr.flush()
# open up file descriptors for the new process
stdin = open(os.devnull, "r")
logout = open(log, "a+", 0)
os.dup2(stdin.fileno(), sys.stdin.fileno())
os.dup2(logout.fileno(), sys.stdout.fileno())
os.dup2(logout.fileno(), sys.stderr.fileno())
# if requested, set the user id of this process
if uid is not None and setuid is not NotImplemented:
setuid(uid)
elif uid is not None:
logger.warning(
"--uid was requested but `setuid` is not "
"implemented on %s" % OS.title())
# if requested, set the group id of this process
if gid is not None and setgid is not NotImplemented:
setgid(gid)
elif gid is not None:
logger.warning(
"--gid was requested but `setgid` is not "
"implemented on %s" % OS.title())