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", ]