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| from __future__ import annotations | |
| import os | |
| import sys | |
| from contextlib import suppress | |
| from errno import ENOSYS | |
| from pathlib import Path | |
| from typing import cast | |
| from ._api import BaseFileLock | |
| from ._util import ensure_directory_exists | |
| #: a flag to indicate if the fcntl API is available | |
| has_fcntl = False | |
| if sys.platform == "win32": # pragma: win32 cover | |
| class UnixFileLock(BaseFileLock): | |
| """Uses the :func:`fcntl.flock` to hard lock the lock file on unix systems.""" | |
| def _acquire(self) -> None: | |
| raise NotImplementedError | |
| def _release(self) -> None: | |
| raise NotImplementedError | |
| else: # pragma: win32 no cover | |
| try: | |
| import fcntl | |
| except ImportError: | |
| pass | |
| else: | |
| has_fcntl = True | |
| class UnixFileLock(BaseFileLock): | |
| """Uses the :func:`fcntl.flock` to hard lock the lock file on unix systems.""" | |
| def _acquire(self) -> None: | |
| ensure_directory_exists(self.lock_file) | |
| open_flags = os.O_RDWR | os.O_TRUNC | |
| if not Path(self.lock_file).exists(): | |
| open_flags |= os.O_CREAT | |
| fd = os.open(self.lock_file, open_flags, self._context.mode) | |
| with suppress(PermissionError): # This locked is not owned by this UID | |
| os.fchmod(fd, self._context.mode) | |
| try: | |
| fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB) | |
| except OSError as exception: | |
| os.close(fd) | |
| if exception.errno == ENOSYS: # NotImplemented error | |
| msg = "FileSystem does not appear to support flock; use SoftFileLock instead" | |
| raise NotImplementedError(msg) from exception | |
| else: | |
| self._context.lock_file_fd = fd | |
| def _release(self) -> None: | |
| # Do not remove the lockfile: | |
| # https://github.com/tox-dev/py-filelock/issues/31 | |
| # https://stackoverflow.com/questions/17708885/flock-removing-locked-file-without-race-condition | |
| fd = cast(int, self._context.lock_file_fd) | |
| self._context.lock_file_fd = None | |
| fcntl.flock(fd, fcntl.LOCK_UN) | |
| os.close(fd) | |
| __all__ = [ | |
| "UnixFileLock", | |
| "has_fcntl", | |
| ] | |