From f3bf8033276aa4fc272940e650c319c517bb3479 Mon Sep 17 00:00:00 2001 From: Lumir Balhar Date: Tue, 7 Apr 2026 09:16:08 +0200 Subject: [PATCH] Python 3.15+ requires C-contiguous buffers for int.from_bytes() --- src/websockets/utils.py | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/websockets/utils.py b/src/websockets/utils.py index b2a90e52..84904ea0 100644 --- a/src/websockets/utils.py +++ b/src/websockets/utils.py @@ -47,6 +47,14 @@ def apply_mask(data: BytesLike, mask: bytes | bytearray) -> bytes: if len(mask) != 4: raise ValueError("mask must contain 4 bytes") + # Python 3.15+ requires C-contiguous buffers for int.from_bytes() + # CPython (https://github.com/python/cpython/pull/132109) optimized + # int.from_bytes() to use the buffer protocol with PyBUF_SIMPLE, which requires + # C-contiguous buffers. Non-contiguous memoryviews (e.g., created by [::-1]) + # now raise BufferError. Convert to bytes to create a contiguous copy. + if isinstance(data, memoryview) and not data.c_contiguous: + data = bytes(data) + data_int = int.from_bytes(data, sys.byteorder) mask_repeated = mask * (len(data) // 4) + mask[: len(data) % 4] mask_int = int.from_bytes(mask_repeated, sys.byteorder)