init

.venv/lib/python3.8/site-packages/filelock/_unix.py

@@ -0,0 +1,56 @@
+from __future__ import annotations
+
+import os
+import sys
+from typing import cast
+
+from ._api import BaseFileLock
+
+#: 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:
+            open_mode = os.O_RDWR | os.O_CREAT | os.O_TRUNC
+            fd = os.open(self._lock_file, open_mode)
+            try:
+                fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
+            except OSError:
+                os.close(fd)
+            else:
+                self._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._lock_file_fd)
+            self._lock_file_fd = None
+            fcntl.flock(fd, fcntl.LOCK_UN)
+            os.close(fd)
+
+
+__all__ = [
+    "has_fcntl",
+    "UnixFileLock",
+]