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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 18:05:20 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 18:05:20 +0000 |
commit | c86df75ab11643fa4649cfe6ed5c4692d4ee342b (patch) | |
tree | de847f47ec2669e74b9a3459319579346b7c99df /pre_commit/file_lock.py | |
parent | Initial commit. (diff) | |
download | pre-commit-c86df75ab11643fa4649cfe6ed5c4692d4ee342b.tar.xz pre-commit-c86df75ab11643fa4649cfe6ed5c4692d4ee342b.zip |
Adding upstream version 3.6.2.upstream/3.6.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | pre_commit/file_lock.py | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/pre_commit/file_lock.py b/pre_commit/file_lock.py new file mode 100644 index 0000000..d3dafb4 --- /dev/null +++ b/pre_commit/file_lock.py @@ -0,0 +1,75 @@ +from __future__ import annotations + +import contextlib +import errno +import sys +from collections.abc import Generator +from typing import Callable + + +if sys.platform == 'win32': # pragma: no cover (windows) + import msvcrt + + # https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/locking + + # on windows we lock "regions" of files, we don't care about the actual + # byte region so we'll just pick *some* number here. + _region = 0xffff + + @contextlib.contextmanager + def _locked( + fileno: int, + blocked_cb: Callable[[], None], + ) -> Generator[None, None, None]: + try: + msvcrt.locking(fileno, msvcrt.LK_NBLCK, _region) + except OSError: + blocked_cb() + while True: + try: + msvcrt.locking(fileno, msvcrt.LK_LOCK, _region) + except OSError as e: + # Locking violation. Returned when the _LK_LOCK or _LK_RLCK + # flag is specified and the file cannot be locked after 10 + # attempts. + if e.errno != errno.EDEADLOCK: + raise + else: + break + + try: + yield + finally: + # From cursory testing, it seems to get unlocked when the file is + # closed so this may not be necessary. + # The documentation however states: + # "Regions should be locked only briefly and should be unlocked + # before closing a file or exiting the program." + msvcrt.locking(fileno, msvcrt.LK_UNLCK, _region) +else: # pragma: win32 no cover + import fcntl + + @contextlib.contextmanager + def _locked( + fileno: int, + blocked_cb: Callable[[], None], + ) -> Generator[None, None, None]: + try: + fcntl.flock(fileno, fcntl.LOCK_EX | fcntl.LOCK_NB) + except OSError: # pragma: no cover (tests are single-threaded) + blocked_cb() + fcntl.flock(fileno, fcntl.LOCK_EX) + try: + yield + finally: + fcntl.flock(fileno, fcntl.LOCK_UN) + + +@contextlib.contextmanager +def lock( + path: str, + blocked_cb: Callable[[], None], +) -> Generator[None, None, None]: + with open(path, 'a+') as f: + with _locked(f.fileno(), blocked_cb): + yield |