ansible-later/testenv/lib/python2.7/site-packages/ansible/module_utils/common/file.py
2019-04-23 13:04:27 +02:00

134 lines
4.0 KiB
Python

# Copyright (c) 2018, Ansible Project
# Simplified BSD License (see licenses/simplified_bsd.txt or https://opensource.org/licenses/BSD-2-Clause)
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import errno
import os
import stat
import re
import pwd
import grp
import time
import shutil
import traceback
import fcntl
import sys
from contextlib import contextmanager
from ansible.module_utils._text import to_bytes, to_native, to_text
from ansible.module_utils.six import b, binary_type
try:
import selinux
HAVE_SELINUX = True
except ImportError:
HAVE_SELINUX = False
class LockTimeout(Exception):
pass
def is_executable(path):
'''is the given path executable?
Limitations:
* Does not account for FSACLs.
* Most times we really want to know "Can the current user execute this
file" This function does not tell us that, only if an execute bit is set.
'''
# These are all bitfields so first bitwise-or all the permissions we're
# looking for, then bitwise-and with the file's mode to determine if any
# execute bits are set.
return ((stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH) & os.stat(path)[stat.ST_MODE])
class FileLock:
'''
Currently FileLock is implemented via fcntl.flock on a lock file, however this
behaviour may change in the future. Avoid mixing lock types fcntl.flock,
fcntl.lockf and module_utils.common.file.FileLock as it will certainly cause
unwanted and/or unexpected behaviour
'''
def __init__(self):
self.lockfd = None
@contextmanager
def lock_file(self, path, tmpdir, lock_timeout=None):
'''
Context for lock acquisition
'''
try:
self.set_lock(path, tmpdir, lock_timeout)
yield
finally:
self.unlock()
def set_lock(self, path, tmpdir, lock_timeout=None):
'''
Create a lock file based on path with flock to prevent other processes
using given path.
Please note that currently file locking only works when it's executed by
the same user, I.E single user scenarios
:kw path: Path (file) to lock
:kw tmpdir: Path where to place the temporary .lock file
:kw lock_timeout:
Wait n seconds for lock acquisition, fail if timeout is reached.
0 = Do not wait, fail if lock cannot be acquired immediately,
Default is None, wait indefinitely until lock is released.
:returns: True
'''
lock_path = os.path.join(tmpdir, 'ansible-{0}.lock'.format(os.path.basename(path)))
l_wait = 0.1
r_exception = IOError
if sys.version_info[0] == 3:
r_exception = BlockingIOError
self.lockfd = open(lock_path, 'w')
if lock_timeout <= 0:
fcntl.flock(self.lockfd, fcntl.LOCK_EX | fcntl.LOCK_NB)
os.chmod(lock_path, stat.S_IWRITE | stat.S_IREAD)
return True
if lock_timeout:
e_secs = 0
while e_secs < lock_timeout:
try:
fcntl.flock(self.lockfd, fcntl.LOCK_EX | fcntl.LOCK_NB)
os.chmod(lock_path, stat.S_IWRITE | stat.S_IREAD)
return True
except r_exception:
time.sleep(l_wait)
e_secs += l_wait
continue
self.lockfd.close()
raise LockTimeout('{0} sec'.format(lock_timeout))
fcntl.flock(self.lockfd, fcntl.LOCK_EX)
os.chmod(lock_path, stat.S_IWRITE | stat.S_IREAD)
return True
def unlock(self):
'''
Make sure lock file is available for everyone and Unlock the file descriptor
locked by set_lock
:returns: True
'''
if not self.lockfd:
return True
try:
fcntl.flock(self.lockfd, fcntl.LOCK_UN)
self.lockfd.close()
except ValueError: # file wasn't opened, let context manager fail gracefully
pass
return True