Class WindowsFileLock

src/filelock/_windows.py:50–95

Uses the :func:`msvcrt.locking` function to hard lock the lock file on Windows systems. Lock file cleanup: Windows attempts to delete the lock file after release, but deletion is not guaranteed in multi-threaded scenarios where another thread holds an open handle. The lock

        return bool(attrs & FILE_ATTRIBUTE_REPARSE_POINT)

    class WindowsFileLock(BaseFileLock):
        """
        Uses the :func:`msvcrt.locking` function to hard lock the lock file on Windows systems.

        Lock file cleanup: Windows attempts to delete the lock file after release, but deletion is
        not guaranteed in multi-threaded scenarios where another thread holds an open handle. The lock
        file may persist on disk, which does not affect lock correctness.
        """

        def _acquire(self) -> None:
            raise_on_not_writable_file(self.lock_file)
            ensure_directory_exists(self.lock_file)

            # Security check: Refuse to open reparse points (symlinks, junctions)
            # This prevents TOCTOU symlink attacks (CVE-TBD)
            if _is_reparse_point(self.lock_file):
                msg = f"Lock file is a reparse point (symlink/junction): {self.lock_file}"
                raise OSError(msg)

            flags = (
                os.O_RDWR  # open for read and write
                | os.O_CREAT  # create file if not exists
            )
            try:
                fd = os.open(self.lock_file, flags, self._open_mode())
            except OSError as exception:
                if exception.errno != EACCES:  # has no access to this lock
                    raise
            else:
                try:
                    msvcrt.locking(fd, msvcrt.LK_NBLCK, 1)
                except OSError as exception:
                    os.close(fd)  # close file first
                    if exception.errno != EACCES:  # file is already locked
                        raise
                else:
                    self._context.lock_file_fd = fd

        def _release(self) -> None:
            fd = cast("int", self._context.lock_file_fd)
            self._context.lock_file_fd = None
            msvcrt.locking(fd, msvcrt.LK_UNLCK, 1)
            os.close(fd)

            with suppress(OSError):
                Path(self.lock_file).unlink()

else:  # pragma: win32 no cover