[PR #13415/8c8906a1 backport][3.15] Fix oversized frames on websocket messages

[patchback]

This is a backport of PR #13415 as merged into master (8c8906a).

[greptile-apps]

Confidence Score: 4/5

This needs correction before merging because supported 32-bit Cython builds still fail before the new oversized-frame guard and cannot pass the added regression test.

The unpacked 64-bit wire length is narrowed into a platform-width Py_ssize_t before the changed comparison, so the fix and test work on 64-bit targets but overflow first on supported 32-bit extension builds.

Files Needing Attention: aiohttp/_websocket/reader_py.py, aiohttp/_websocket/reader_c.pxd, tests/test_websocket_parser.py

_{Reviews (1): Last reviewed commit: "Fix oversized frames on websocket messag..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.21%. Comparing base (5ffad54) to head (a904e67).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             3.15   #13493   +/-   ##
=======================================
  Coverage   96.21%   96.21%           
=======================================
  Files         159      159           
  Lines       51067    51076    +9     
  Branches     2776     2776           
=======================================
+ Hits        49135    49144    +9     
  Misses       1751     1751           
  Partials      181      181           

Flag	Coverage Δ
CI-GHA	96.18% <100.00%> (+<0.01%)	⬆️
OS-Linux	95.96% <100.00%> (-0.01%)	⬇️
OS-Windows	93.67% <81.81%> (+<0.01%)	⬆️
OS-macOS	95.15% <81.81%> (+<0.01%)	⬆️
Py-3.10	95.31% <100.00%> (+<0.01%)	⬆️
Py-3.11	95.57% <100.00%> (+<0.01%)	⬆️
Py-3.12	95.65% <100.00%> (-0.01%)	⬇️
Py-3.13	95.64% <100.00%> (+<0.01%)	⬆️
Py-3.14	95.75% <100.00%> (+<0.01%)	⬆️
Py-3.14t	94.75% <81.81%> (-0.01%)	⬇️
Py-pypy-3.11	94.60% <100.00%> (-0.01%)	⬇️
VM-macos	95.15% <81.81%> (+<0.01%)	⬆️
VM-ubuntu	95.96% <100.00%> (-0.01%)	⬇️
VM-windows	93.67% <81.81%> (+<0.01%)	⬆️
cython-coverage	78.17% <90.90%> (-0.01%)	⬇️

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[codspeed-hq]

Merging this PR will not alter performance

✅ 84 untouched benchmarks
⏩ 86 skipped benchmarks¹

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_{Comparing patchback/backports/3.15/8c8906a19f64e52ef6a7d44d65217eb3c5af413f/pr-13415 (a904e67) with 3.15 (5ffad54)}

Footnotes

1. 86 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩