Current File : //opt/alt/python37/lib/python3.7/site-packages/filelock/_windows.py
from __future__ import annotations
import os
import sys
from abc import ABC
from errno import ENOENT
from typing import cast
from ._api import BaseFileLock
from ._util import raise_on_exist_ro_file
if sys.platform == "win32": # pragma: win32 cover
import msvcrt
class WindowsFileLock(BaseFileLock):
"""Uses the :func:`msvcrt.locking` function to hard lock the lock file on windows systems."""
def _acquire(self) -> None:
raise_on_exist_ro_file(self._lock_file)
mode = (
os.O_RDWR # open for read and write
| os.O_CREAT # create file if not exists
| os.O_TRUNC # truncate file if not empty
)
try:
fd = os.open(self._lock_file, mode)
except OSError as exception:
if exception.errno == ENOENT: # No such file or directory
raise
else:
try:
msvcrt.locking(fd, msvcrt.LK_NBLCK, 1)
except OSError:
os.close(fd)
else:
self._lock_file_fd = fd
def _release(self) -> None:
fd = cast(int, self._lock_file_fd)
self._lock_file_fd = None
msvcrt.locking(fd, msvcrt.LK_UNLCK, 1)
os.close(fd)
try:
os.remove(self._lock_file)
# Probably another instance of the application hat acquired the file lock.
except OSError:
pass
else: # pragma: win32 no cover
class WindowsFileLock(BaseFileLock, ABC):
"""Uses the :func:`msvcrt.locking` function to hard lock the lock file on windows systems."""
__all__ = [
"WindowsFileLock",
]
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