* 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>
* Work correctly if an additional fresh module imports other
additional fresh module which imports a blocked module.
* Raises ImportError if the specified module cannot be imported
while all additional fresh modules are successfully imported.
* Support blocking packages.
* Always restore the import state of fresh and blocked modules
and their submodules.
* Fix test_decimal and test_xml_etree which depended on an undesired
side effect of import_fresh_module().
(cherry picked from commit ec4d917a6a)
* When trying to allocate very large regions on macOS, malloc does not fail silently. It sends a noisy error out to STDERR
* This provides a helper function to warn the user, and provides the warning for test_decimal, which consistently generates these warnings on macOS.
Co-authored-by: Łukasz Langa <lukasz@langa.pl>.
(cherry picked from commit 15d3c14df3)
Co-authored-by: Jack DeVries <58614260+jdevries3133@users.noreply.github.com>
- AIX has extreme over-allocation that is in no relation to the physical
RAM and swap.
(cherry picked from commit 39dab24621)
Authored-by: Stefan Krah <skrah@bytereef.org>
Capturing exceptions into names can lead to reference cycles though the __traceback__ attribute of the exceptions in some obscure cases that have been reported previously and fixed individually. As these variables are not used anyway, we can remove the binding to reduce the chances of creating reference cycles.
See for example GH-13135
Two kind of mistakes:
1. Missed space. After concatenating there is no space between words.
2. Missed comma. Causes unintentional concatenating in a list of strings.
_decimal:
o Make all "mpd_t to C integer" conversion functions available in both the
64-bit and the 32-bit versions.
o Make all mixed mpd_t/C integer arithmetic functions available in the
32-bit version.
o Better handling of __STDC_LIMIT_MACROS for C++ users.
o Add struct tags (at the request of C++ users).
2) Check for libmpdec.so.2 if --with-system-libmpdec is used.
