gh-151510: Fix __lazy_import__ without frame (GH-151511)
(cherry picked from commit eff805b7a7)
Co-authored-by: AN Long <aisk@users.noreply.github.com>
The standard says that a call to `memcpy` must pass a valid source and
destination pointer even if the size is 0, so we must avoid calling
`memcpy` when our source pointer is NULL. If we don't, an optimizing
compiler can decide that the pointer must be non-NULL based on the
presence of UB, and optimize out checks for null pointers.
Specifically, note that the standard says:
Where an argument declared as size_t n specifies the length of the
array for a function, n can have the value zero on a call to that
function. Unless explicitly stated otherwise in the description of
a particular function in this subclause, pointer arguments on such
a call shall still have valid values, as described in 7.1.4.
And section 7.1.4 says:
If an argument to a function has an invalid value (such as a value
outside the domain of the function, or a pointer outside the address
space of the program, or a null pointer, or a pointer to
non-modifiable storage when the corresponding parameter is not
const-qualified) or a type (after default argument promotion) not
expected by a function with a variable number of arguments, the
behavior is undefined.
The specification for `memcpy` doesn't state that it's allowed to be
called with null pointers, and Linux's `/usr/include/string.h` declares
`memcpy` as `__nonnull ((1, 2))`.
(cherry picked from commit c37599200f)
Co-authored-by: Matt Wozniski <mwozniski@bloomberg.net>
In free-threaded builds, concurrent calls to PyDict_AddWatcher, PyDict_ClearWatcher, PyDict_Watch, and PyDict_Unwatch can race on the shared callback array and the per-dict watcher tags. This change adds a mutex to serialize watcher registration and removal, atomic operations for tag updates, and atomic acquire/release synchronization for callback dispatch in _PyDict_SendEvent.
(cherry picked from commit 8a4895985f)
Co-authored-by: Alper <alperyoney@fb.com>
There are newly documented restrictions on tp_traverse:
The traversal function must not have any side effects.
It must not modify the reference counts of any Python
objects nor create or destroy any Python objects.
* Add several functions that are guaranteed side-effect-free,
with a _DuringGC suffix.
* Use these in ctypes
* Consolidate tp_traverse docs in gcsupport.rst, moving unique
content from typeobj.rst there
Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
Co-authored-by: Victor Stinner <vstinner@python.org>
When Python is built in debug mode:
* long_alloc() now initializes digits with a pattern to detect usage of
uninitialized digits.
* _PyLong_CompactValue() now makes sure that the digit is zero when the
sign is zero.
* PyLongWriter_Finish() now raises SystemError if it detects uninitialized
digits
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
The long_from_string_base() might return a small integer, when the
_pylong.py is used to do conversion. Hence, we must be careful here to
not smash it "small int" bit by using the _PyLong_FlipSign().
Co-authored-by: Victor Stinner <vstinner@python.org>
Add PyArg_ParseArray() and PyArg_ParseArrayAndKeywords()
functions to parse arguments of functions using the METH_FASTCALL
calling convention.
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
When integrating slots-based module creation is with the inittab,
which currently requires PyModuleDef, it would be convenient to
reuse the the same slots array for the MethodDef.
Allow slots that match what's already present in the PyModuleDef.
This ensures the buffers used by the empty `bytearray` and `array.array`
are aligned the same as a pointer returned by the allocator. This is a
more convenient default for interop with other languages that have
stricter requirements of type-safe buffers (e.g. Rust's `&[T]` type)
even when empty.
* Promote _PyObject_Dump() as a public function.
* Keep _PyObject_Dump() alias to PyUnstable_Object_Dump()
for backward compatibility.
* Replace _PyObject_Dump() with PyUnstable_Object_Dump().
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
Co-authored-by: Kumar Aditya <kumaraditya@python.org>
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Use multiphase initialization in the _testcapi module to allow loading in subinterpreters. The isolation here isn't perfect as there's still some use of globals, but _testcapi should generally work in other interpreters.
- Use %T format specifier instead of %s and Py_TYPE(x)->tp_name.
- Remove legacy %.200s format specifier for truncating type names.
Co-authored-by: Victor Stinner <vstinner@python.org>
Replace most PyUnicodeWriter_WriteUTF8() calls with
PyUnicodeWriter_WriteASCII().
Unrelated change to please the linter: remove an unused
import in test_ctypes.
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
After gh-130704, the interpreter replaces some uses of `LOAD_FAST` with
`LOAD_FAST_BORROW` which avoid incref/decrefs by "borrowing" references
on the interpreter stack when the bytecode compiler can determine that
it's safe.
This change broke some checks in C API extensions that relied on
`Py_REFCNT()` of `1` to determine if it's safe to modify an object
in-place. Objects may have a reference count of one, but still be
referenced further up the interpreter stack due to borrowing of
references.
This provides a replacement function for those checks.
`PyUnstable_Object_IsUniqueReferencedTemporary` is more conservative:
it checks that the object has a reference count of one and that it exists as a
unique strong reference in the interpreter's stack of temporary
variables in the top most frame.
See also:
* https://github.com/numpy/numpy/issues/28681
Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com>
Co-authored-by: T. Wouters <thomas@python.org>
Co-authored-by: mpage <mpage@cs.stanford.edu>
Co-authored-by: Mark Shannon <mark@hotpy.org>
Co-authored-by: Victor Stinner <vstinner@python.org>
* Skip sNaN's testing in 32-bit mode.
* Drop float_set_snan() helper.
* Use memcpy() workaround for sNaN's in PyFloat_Unpack4().
* Document, that sNaN's may not be preserved by PyFloat_Pack/Unpack API.
