* Correctly pre-check for int-to-str conversion (#96537)
Converting a large enough `int` to a decimal string raises `ValueError` as expected. However, the raise comes _after_ the quadratic-time base-conversion algorithm has run to completion. For effective DOS prevention, we need some kind of check before entering the quadratic-time loop. Oops! =)
The quick fix: essentially we catch _most_ values that exceed the threshold up front. Those that slip through will still be on the small side (read: sufficiently fast), and will get caught by the existing check so that the limit remains exact.
The justification for the current check. The C code check is:
```c
max_str_digits / (3 * PyLong_SHIFT) <= (size_a - 11) / 10
```
In GitHub markdown math-speak, writing $M$ for `max_str_digits`, $L$ for `PyLong_SHIFT` and $s$ for `size_a`, that check is:
$$\left\lfloor\frac{M}{3L}\right\rfloor \le \left\lfloor\frac{s - 11}{10}\right\rfloor$$
From this it follows that
$$\frac{M}{3L} < \frac{s-1}{10}$$
hence that
$$\frac{L(s-1)}{M} > \frac{10}{3} > \log_2(10).$$
So
$$2^{L(s-1)} > 10^M.$$
But our input integer $a$ satisfies $|a| \ge 2^{L(s-1)}$, so $|a|$ is larger than $10^M$. This shows that we don't accidentally capture anything _below_ the intended limit in the check.
<!-- gh-issue-number: gh-95778 -->
* Issue: gh-95778
<!-- /gh-issue-number -->
Co-authored-by: Gregory P. Smith [Google LLC] <greg@krypto.org>
Co-authored-by: Christian Heimes <christian@python.org>
Co-authored-by: Mark Dickinson <dickinsm@gmail.com>
Remove --with-experimental-isolated-subinterpreters configure option
in Python 3.9: the experiment continues in the master branch, but
it's no longer needed in 3.9.
Move PyInterpreterState.fs_codec into a new
PyInterpreterState.unicode structure.
Give a name to the fs_codec structure and use this structure in
unicodeobject.c.
In the experimental isolated subinterpreters build mode, the GIL is
now per-interpreter.
Move gil from _PyRuntimeState.ceval to PyInterpreterState.ceval.
new_interpreter() always get the config from the main interpreter.
Move recursion_limit member from _PyRuntimeState.ceval to
PyInterpreterState.ceval.
* Py_SetRecursionLimit() now only sets _Py_CheckRecursionLimit
of ceval.c if the current Python thread is part of the main
interpreter.
* Inline _Py_MakeEndRecCheck() into _Py_LeaveRecursiveCall().
* Convert _Py_RecursionLimitLowerWaterMark() macro into a static
inline function.
* Replace PY_INT64_T with int64_t
* Replace PY_UINT32_T with uint32_t
* Replace PY_UINT64_T with uint64_t
sha3module.c no longer checks if PY_UINT64_T is defined since it's
always defined and uint64_t is always available on platforms
supported by Python.
Gregory P. Smith