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Optional support for ieee contexts in the decimal module doesn't work #122081
Description
Crash report
What happened?
Reproducer:
$ ./configure CFLAGS=-DEXTRA_FUNCTIONALITY -q && make -s
configure: WARNING: no system libmpdecimal found; falling back to bundled libmpdecimal (deprecated and scheduled for removal in Python 3.15)
In function ‘word_to_string’,
inlined from ‘coeff_to_string’ at ./Modules/_decimal/libmpdec/io.c:411:13,
inlined from ‘_mpd_to_string’ at ./Modules/_decimal/libmpdec/io.c:612:18:
./Modules/_decimal/libmpdec/io.c:349:40: warning: writing 1 byte into a region of size 0 [-Wstringop-overflow=]
349 | if (s == dot) *s++ = '.'; *s++ = '0' + (char)(x / d); x %= d
| ~~~~~^~~~~~~~~~~~~~~~~~~~~
./Modules/_decimal/libmpdec/io.c:360:14: note: in expansion of macro ‘EXTRACT_DIGIT’
360 | case 15: EXTRACT_DIGIT(s, x, 100000000000000ULL, dot);
| ^~~~~~~~~~~~~
[... and similar warnings from issue #108562, hardly relevant]
Checked 112 modules (34 built-in, 77 shared, 1 n/a on linux-x86_64, 0 disabled, 0 missing, 0 failed on import)
$ ./python
Python 3.14.0a0 (heads/main:cecaceea31, Jul 19 2024, 05:34:00) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from decimal import *
>>> IEEEContext(11)
Traceback (most recent call last):
File "<python-input-1>", line 1, in <module>
IEEEContext(11)
~~~~~~~~~~~^^^^
ValueError: argument must be a multiple of 32, with a maximum of 512
>>> IEEEContext(1024)
Traceback (most recent call last):
File "<python-input-2>", line 1, in <module>
IEEEContext(1024)
~~~~~~~~~~~^^^^^^
ValueError: argument must be a multiple of 32, with a maximum of 512
>>> IEEEContext(512) # oops
Segmentation fault
There are tests (decorated by @requires_extra_functionality) for this, but it seems nobody (including build bots) run this a long time. These tests are broken too (crash).
I'll provide a patch.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.14.0a0 (heads/fix-decimal-extra:c8d2630995, Jul 21 2024, 10:20:04) [GCC 12.2.0]
Activity
pythongh-122081: fixed crash in decimal.IEEEContext()
skirpichev commented on Jul 21, 2024
PR is ready for review: #122082
skirpichev commented on Aug 18, 2024
Gentle ping (per devguide).
picnixz commented on Aug 18, 2024
@skirpichev As a mathematician, I'm always interested in your PRs so feel free to ping me / request a review in general!
skirpichev commented on Aug 18, 2024
Thanks, @picnixz! When it does make sense for you, feel free to ask me for review.
gh-122081: fixed crash in decimal.IEEEContext() (#122082)
pythongh-122081: fixed crash in decimal.IEEEContext() (pythonGH-122082)
[3.13] gh-122081: fixed crash in decimal.IEEEContext() (GH-122082) (#…
picnixz commented on Aug 19, 2024
Closing since completed in #122082 and backported in #123136.
picnixz commented on Aug 19, 2024
Re-opening because the 3.12 backport is actually missing.
@skirpichev @kumaraditya303 Either of you should do the 3.12 backport manually since it failed.
skirpichev commented on Aug 19, 2024
I'm working on this. Probably, that backport isn't required.
skirpichev commented on Aug 19, 2024
Yeah, it works without the patch. @picnixz, you can remove label.
pythongh-122081: fixed crash in decimal.IEEEContext() (python#122082)
pythongh-122081: fixed crash in decimal.IEEEContext() (python#122082)