Brett Cannon [Fri, 5 Dec 2025 23:27:16 +0000 (15:27 -0800)]
GH-142234: Allow `--enable-wasm-dynamic-linking` under WASI (GH-142235)
While CPython doesn't support `--enable-wasm-dynamic-linking`, external tools like componentize-py do and they have to patch around it. Since the flag is off by default, allowing the flag so external users can add/inject dynamic linking support seems acceptable.
gh-115952: Fix a potential virtual memory allocation denial of service in pickle (GH-119204)
Loading a small data which does not even involve arbitrary code execution
could consume arbitrary large amount of memory. There were three issues:
* PUT and LONG_BINPUT with large argument (the C implementation only).
Since the memo is implemented in C as a continuous dynamic array, a single
opcode can cause its resizing to arbitrary size. Now the sparsity of
memo indices is limited.
* BINBYTES, BINBYTES8 and BYTEARRAY8 with large argument. They allocated
the bytes or bytearray object of the specified size before reading into
it. Now they read very large data by chunks.
* BINSTRING, BINUNICODE, LONG4, BINUNICODE8 and FRAME with large
argument. They read the whole data by calling the read() method of
the underlying file object, which usually allocates the bytes object of
the specified size before reading into it. Now they read very large data
by chunks.
Also add comprehensive benchmark suite to measure performance and memory
impact of chunked reading optimization in PR #119204.
Features:
- Normal mode: benchmarks legitimate pickles (time/memory metrics)
- Antagonistic mode: tests malicious pickles (DoS protection)
- Baseline comparison: side-by-side comparison of two Python builds
- Support for truncated data and sparse memo attack vectors
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com> Co-authored-by: Gregory P. Smith <greg@krypto.org>
Sanyam Khurana [Fri, 5 Dec 2025 12:18:54 +0000 (07:18 -0500)]
gh-48752: Add readline.get_pre_input_hook() function (#141586)
Add readline.get_pre_input_hook() to retrieve the current pre-input
hook. This allows applications to save and restore the hook without
overwriting user settings.
This fixes a regression introduced in gh-140558. The interpreter would
crash if we inserted a non `str` key into a split table that matches an
existing key.
Sam Gross [Wed, 3 Dec 2025 20:48:44 +0000 (15:48 -0500)]
gh-140482: Avoid changing terminal settings in test_pty (gh-142202)
The previous test_spawn_doesnt_hang test had a few problems:
* It would cause ENV CHANGED failures if other tests were running
concurrently due to stty changes
* Typing while the test was running could cause it to fail
Mark Shannon [Wed, 3 Dec 2025 17:43:35 +0000 (17:43 +0000)]
GH-141794: Limit size of generated machine code. (GH-142228)
* Factor out bodies of the largest uops, to reduce jit code size.
* Factor out common assert, also reducing jit code size.
* Limit size of jitted code for a single executor to 1MB.
Petr Viktorin [Wed, 3 Dec 2025 15:14:53 +0000 (16:14 +0100)]
gh-135676: Reword the f-string (and t-string) section (GH-137469)
Much of the information was duplicated in stdtypes.rst; this PR keeps lexical/syntactical details in Lexical Analysis and the evaluation & runtime behaviour in Standard types, with cross-references between the two.
Since the t-string section only listed differences from f-strings, and the grammar for the two is equivalent, that section was moved to Standard types almost entirely.
Co-authored-by: Blaise Pabon <blaise@gmail.com> Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com> Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
gh-119342: Fix a potential denial of service in plistlib (GH-119343)
Reading a specially prepared small Plist file could cause OOM because file's
read(n) preallocates a bytes object for reading the specified amount of
data. Now plistlib reads large data by chunks, therefore the upper limit of
consumed memory is proportional to the size of the input file.
gh-119451: Fix a potential denial of service in http.client (GH-119454)
Reading the whole body of the HTTP response could cause OOM if
the Content-Length value is too large even if the server does not send
a large amount of data. Now the HTTP client reads large data by chunks,
therefore the amount of consumed memory is proportional to the amount
of sent data.
Gregory P. Smith [Sat, 29 Nov 2025 06:07:03 +0000 (22:07 -0800)]
gh-87512: Fix `subprocess` using `timeout=` on Windows blocking with a large `input=` (GH-142058)
On Windows, Popen._communicate() previously wrote to stdin synchronously, which could block indefinitely if the subprocess didn't consume input= quickly and the pipe buffer filled up. The timeout= parameter was only checked when joining the reader threads, not during the stdin write.
This change moves the Windows stdin writing to a background thread (similar to how stdout/stderr are read in threads), allowing the timeout to be properly enforced. If timeout expires, TimeoutExpired is raised promptly and the writer thread continues in the background. Subsequent calls to communicate() will join the existing writer thread.
Adds test_communicate_timeout_large_input to verify that TimeoutExpired is raised promptly when communicate() is called with large input and a timeout, even when the subprocess doesn't consume stdin quickly.
This test already passed on POSIX (where select() is used) but failed on Windows where the stdin write blocks without checking the timeout.
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Gregory P. Smith [Sat, 29 Nov 2025 04:25:06 +0000 (20:25 -0800)]
GH-134453: Fix subprocess memoryview input handling on POSIX (GH-134949)
Fix inconsistent subprocess.Popen.communicate() behavior between Windows
and POSIX when using memoryview objects with non-byte elements as input.
On POSIX systems, the code was incorrectly comparing bytes written against
element count instead of byte count, causing data truncation for large
inputs with non-byte element types.
Changes:
- Cast memoryview inputs to byte view when input is already a memoryview
- Fix progress tracking to use len(input_view) instead of len(self._input)
- Add comprehensive test coverage for memoryview inputs
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
* old-man-yells-at-ReST
* Update 2025-05-30-18-37-44.gh-issue-134453.kxkA-o.rst
* assertIsNone review feedback
* fix memoryview_nonbytes test to fail without our fix on main, and have a nicer error.
Thanks to Peter Bierma @ZeroIntensity for the code review.
Artur Jamro [Sat, 29 Nov 2025 02:04:52 +0000 (03:04 +0100)]
gh-141473: Fix subprocess.Popen.communicate to send input to stdin upon a subsequent post-timeout call (GH-141477)
* gh-141473: Fix subprocess.Popen.communicate to send input to stdin
* Docs: Clarify that `input` is one time only on `communicate()`
* NEWS entry
* Add a regression test.
---------
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Alper [Wed, 26 Nov 2025 20:40:45 +0000 (12:40 -0800)]
gh-116738: Fix thread-safety issue in re module for free threading (gh-141923)
Added atomic operations to `scanner_begin()` and `scanner_end()` to prevent
race conditions on the `executing` flag in free-threaded builds. Also added
tests for concurrent usage of the `re` module.
Without the atomic operations, `test_scanner_concurrent_access()` triggers
`assert(self->executing)` failures, or a thread sanitizer run emits errors.
Petr Viktorin [Wed, 26 Nov 2025 15:10:44 +0000 (16:10 +0100)]
gh-135676: Simplify docs on lexing names (GH-140464)
This simplifies the Lexical Analysis section on Names (but keeps it technically correct) by putting all the info about non-ASCII characters in a separate (and very technical) section.
It uses a mental model where the parser doesn't handle Unicode complexity “immediately”, but:
- parses any non-ASCII character (outside strings/comments) as part of a name, since these can't (yet) be e.g. operators
- normalizes the name
- validates the name, using the xid_start/xid_continue sets
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com> Co-authored-by: Blaise Pabon <blaise@gmail.com> Co-authored-by: Micha Albert <info@micha.zone> Co-authored-by: KeithTheEE <kmurrayis@gmail.com>
Petr Viktorin [Wed, 26 Nov 2025 12:50:03 +0000 (13:50 +0100)]
gh-140550: PEP 793 reference documentation (GH-141197)
* gh-140550: PEP 793 reference documentation
Since the PEP calls for soft-deprecation of the existing initialization
function, this reorganizes the relevant docs to put the new way of
doing things first, and de-emphasize the old.
Some bits, like the tutorial, are left out of this patch. (See the
issue for a list.)
Petr Viktorin [Tue, 25 Nov 2025 13:30:33 +0000 (14:30 +0100)]
gh-139165: Make Py_SIZE, Py_IS_TYPE,Py_ SET_SIZE regular functions in stable ABI (GH-139166)
* Make Py_{SIZE,IS_TYPE,SET_SIZE} regular functions in stable ABI
Group them together with Py_TYPE & Py_SET_TYPE to cut down
on repetitive preprocessor macros.
Format repetitive definitions in object.c more concisely.