GeezerVison is showing github.com — Fix Windows runtime validation and 32-bit string size overflows by youknowone · Pull Request #9412 · RustPython/RustPython
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youknowone
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Oct 28, 2026
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edited by coderabbitai
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Summary
Follow up the Windows runtime fixes in #9406, without C API, ctypes, PyO3, dependency, or CI changes.
- Reject
WSARecvFromInto requests larger than their writable buffer before starting I/O.
- Match CPython's
spawnv argument TypeError while preserving embedded-NUL ValueError and other conversion exceptions.
- Check replacement, tab-expansion, and string-join result sizes before allocation. This fixes capacity-overflow panics and oversized-allocation aborts reproduced in an actual 32-bit Windows process. Fallible allocation is used for tab expansion and string join.
- Add Rust regression tests for length arithmetic, receive validation, and spawnv exceptions. Remove the now-passing Windows expected-failure markers; the redundant socket-test override is removed so the unchanged inherited test runs normally.
Rebased onto upstream/main at 058bebf.
Validation
- Windows x64:
cargo test --workspace --exclude rustpython_wasm --exclude rustpython-venvlauncher --exclude rustpython-capi passed after rebase.
- Windows x64: workspace/all-targets Clippy with the same exclusions and
-D warnings passed. Only the existing linker-messages warning remains (not governed by -D warnings). Separate crates/capi Clippy also passed.
- Actual
i686-pc-windows-msvc interpreter: test_str test_bytes test_struct test_array test_os test_winapi test_subprocess passed (9 expanded test files; reported run=2,357, skipped=589).
- Windows x64 related regression modules passed, including asyncio low-level sockets, os, subprocess, winapi, msvcrt, signal, dbm, and interpreter-pool tests (10 expanded files).
- Existing skipped replacement-overflow tests were also invoked without their skip wrappers at runtime for str, bytes, and bytearray; all passed on x86. Their source skip decorators are unchanged.
- Formatting and all applicable pre-commit hooks passed; focused pre-commit review found no blockers.
C API tests were attempted separately but remain blocked by missing-symbol link errors outside this PR; no C API fixes are included. The separately reproduced Windows subnormal math.remainder issue originates in the external pymath dependency and is also excluded. This PR does not claim that every Windows incompatibility is resolved.
AI assistance
Codex assisted with implementation, investigation, testing, review, and this PR description. Runtime checks were executed on Windows x64 and x86; no human review is claimed.
Summary by CodeRabbit
- Bug Fixes
- Oversized receive requests are rejected before I/O begins.
- String and byte operations now report overflow or allocation failures instead of proceeding with invalid or unavailable output sizes.
- Tab expansion handles zero tab stops and line breaks consistently.
- On MSVC, invalid path-like arguments to
spawnv receive a clearer error; embedded-null errors remain unchanged.
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Validate overlapped receive buffer sizes before starting I/O and preserve spawnv non-TypeError argument failures. Check replacement, tab expansion, and string join sizes before allocation to avoid 32-bit capacity overflows.
Implementation, regression investigation, and validation assisted by Codex.
Assisted-by: Codex:GPT-5
Codex Review Summary
This comment shows the latest Codex review activity on this pull request.
| Review |
Status |
Commit |
Review trigger |
| 📝 Code Review |
⚠️ Failed 2026-10-28T01:39:55.348699Z
We couldn’t complete this review. Comment @codex review to try again. |
bd68b55 |
PR opened |
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coderabbitai
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commented
Oct 28, 2026
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edited
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No actionable comments were generated in the recent review.
 Recent review info
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 Run configuration
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 Commits
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Reviewing files that changed from the base of the PR and between 058bebf and bd68b55.
 Files ignored due to path filters: 2
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Lib/test/test_asyncio/test_sock_lowlevel.py is excluded by !Lib/**Lib/test/test_os/test_os.py is excluded by !Lib/**
 Files selected for processing: 8
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crates/common/src/str.rscrates/stdlib/src/overlapped.rscrates/vm/src/anystr.rscrates/vm/src/builtins/bytearray.rscrates/vm/src/builtins/bytes.rscrates/vm/src/builtins/str.rscrates/vm/src/bytes_inner.rscrates/vm/src/stdlib/nt.rs
Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 9 remain after this review.
Walkthrough
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The changes add checked size calculations and fallible allocation handling for string and bytes operations. They also update tab expansion, validate overlapped receive buffer sizes, and adjust MSVC spawnv argument error mapping.
Changes: String and bytes sizing
| Layer / File(s) |
Summary |
Checked length calculations
crates/vm/src/anystr.rs |
New helpers calculate replacement and tab-expansion lengths with checked arithmetic. Tests cover overflow, size limits, and tab-column behavior. |
Tab expansion
crates/common/src/str.rs, crates/vm/src/anystr.rs, crates/vm/src/builtins/{bytearray.rs,bytes.rs,str.rs}, crates/vm/src/bytes_inner.rs |
The common string function appends expansion to a supplied buffer. String and bytes expansion check output capacity and propagate overflow or allocation errors through their builtin methods. |
Replacement and join sizing
crates/vm/src/builtins/str.rs, crates/vm/src/bytes_inner.rs |
String join and replacement check output sizes and allocation. Bytes replacement uses checked length calculations and propagates errors for empty-pattern replacement. |
Overlapped receive validation
| Layer / File(s) |
Summary |
Receive buffer size check
crates/stdlib/src/overlapped.rs |
WSARecvFromInto rejects a requested size larger than the supplied buffer before changing operation state or starting I/O. A unit test checks the error and unchanged state. |
MSVC spawnv argument errors
| Layer / File(s) |
Summary |
Argument conversion and error mapping
crates/vm/src/stdlib/nt.rs |
On MSVC, argv path-conversion TypeErrors use the specified argument-2 message. Other errors remain unchanged. Tests cover non-string and embedded-null arguments. |
Priority:  Normal
Estimated code review effort: 3 (Moderate) | ~25 minutes
Change: Bug fix
Possibly related PRs
- RustPython/RustPython#9406: The PR description says this change follows up on its Windows runtime fixes. Both changes touch Windows runtime behavior, although they modify separate code paths.
Suggested reviewers: 1ndahous3, luantaraschi, joshuamegnauth54
Merge Risk:  Minimal · up to bd68b
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The changes add checked sizing and Windows input validation. The spawnv exception behavior matches CPython, and no merge-blocking defect remains identified.
Pre-merge checks:  4 ·  1
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Failed checks: 1 warning
| Check name |
Status |
Explanation |
Resolution |
| Docstring Coverage |
 |
Docstring coverage is 23.08% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documenta… |
Write docstrings for the functions missing them to satisfy the coverage threshold. |
Passed checks: 4 passed
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| Check name |
Status |
Explanation |
| Description Check |
 |
Check skipped - CodeRabbit’s high-level summary is enabled. |
| Title check |
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The title clearly and concisely summarizes the main changes: Windows runtime validation fixes and prevention of 32-bit string-size overflows. |
| Linked Issues check |
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Check skipped because no linked issues were found for this pull request. |
| Out of Scope Changes check |
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Check skipped because no linked issues were found for this pull request. |
Full details: Docstring Coverage
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Explanation
Docstring coverage is 23.08% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 13 functions across 8 files.
Resolution
Write docstrings for the functions missing them to satisfy the coverage threshold.
Finishing Touches
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🧪 Generate unit tests (beta)
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- Autofix · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts
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📦 Library Dependencies
The following Lib/ modules were modified. Here are their dependencies:
[x] lib: cpython/Lib/asyncio
[ ] test: cpython/Lib/test/test_asyncio (TODO: 2)
dependencies:
dependent tests: (9 tests)
- asyncio: test_asyncio test_concurrent_futures test_external_inspection test_inspect test_logging test_os test_pdb test_unittest
[x] lib: cpython/Lib/os.py
[x] test: cpython/Lib/test/test_popen.py
dependencies:
dependent tests: (191 tests)
- os: test___all__ test__osx_support test_argparse test_asdl_parser test_ast test_asyncio test_atexit test_base64 test_baseexception test_bdb test_bool test_buffer test_builtin test_bytes test_bz2 test_c_locale_coercion test_calendar test_clinic test_cmd_line test_cmd_line_script test_codecs test_compile test_compileall test_concurrent_futures test_configparser test_contextlib test_ctypes test_curses test_dbm test_dbm_dumb test_dbm_gnu test_dbm_ndbm test_dbm_sqlite3 test_decimal test_devpoll test_doctest test_dtrace test_eintr test_embed test_ensurepip test_enum test_epoll test_exception_hierarchy test_exceptions test_external_inspection test_faulthandler test_fcntl test_file_eintr test_filecmp test_fileinput test_fileutils test_float test_fnmatch test_fork1 test_fractions test_fstring test_ftplib test_future_stmt test_generated_cases test_genericalias test_genericpath test_getpass test_gettext test_glob test_graphlib test_gzip test_hash test_hashlib test_http_cookiejar test_httplib test_httpservers test_imaplib test_importlib test_inspect test_interpreters test_io test_ioctl test_json test_kqueue test_launcher test_linecache test_locale test_logging test_lzma test_mailbox test_marshal test_math test_mimetypes test_mmap test_modulefinder test_msvcrt test_multiprocessing_forkserver test_multiprocessing_main_handling test_netrc test_ntpath test_openpty test_optparse test_os test_pathlib test_pdb test_peg_generator test_perfmaps test_pkg test_pkgutil test_platform test_plistlib test_poll test_popen test_poplib test_posixpath test_profile test_profiling test_pstats test_pty test_py_compile test_pydoc test_pyexpat test_pyrepl test_random test_regrtest test_remote_pdb test_repl test_reprlib test_robotparser test_runpy test_sax test_script_helper test_selectors test_shelve test_shlex test_shutil test_signal test_site test_smtpnet test_socket test_socketserver test_sqlite3 test_ssl test_stat test_string_literals test_strptime test_structseq test_subprocess test_support test_sys test_sys_settrace test_sysconfig test_tabnanny test_tarfile test_tcl test_tempfile test_termios test_thread test_threading test_threadsignals test_time test_tkinter test_tokenize test_tools test_trace test_traceback test_tracemalloc test_tty test_turtle test_typing test_unicode_file test_unicode_file_functions test_unittest test_urllib test_urllib2 test_urllib2_localnet test_urllib2net test_urllibnet test_uuid test_venv test_wait3 test_wait4 test_wave test_webbrowser test_winapi test_winconsoleio test_winreg test_winsound test_wsgiref test_xml_etree test_xpickle test_zipfile test_zipimport test_zipimport_support test_zoneinfo test_zstd
Legend:
[+] path exists in CPython[x] up-to-date, [ ] outdated
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