./Modules/_datetimemodule.c:290: days_before_year: Assertion `year >= 1' failed.

[Vlad4896]

Crash report

What happened?

Python terminates with core dumped on the following test:

import datetime

y = datetime.datetime.fromisoformat('0000W25')
print(y)

The test result:

python: ./Modules/_datetimemodule.c:290: days_before_year: Assertion `year >= 1' failed.
Aborted (core dumped)

The issue happened due to lack of checking for input parameters in iso_to_ymd().
The 'iso_year' input parameter should be checked to fix the issue.

CPython versions tested on:

3.11, 3.12, CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

Python 3.13.0a5+ (heads/main:dc54714044, Apr 4 2024, 12:28:42) [GCC 11.4.0]

Linked PRs

• gh-117534: Add checking for input parameter in iso_to_ymd #117543
• [3.12] gh-117534: Add checking for input parameter in iso_to_ymd (GH-117543) #117689

[Eclips4]

Hello!
Thanks for the report.
Would you like to submit a PR with fix? :)

[hugovk]

For comparison, on macOS:

❯ ./python.exe
Python 3.13.0a5+ (heads/main:9dae05ee59, Apr  4 2024, 13:17:17) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import datetime
>>> y = datetime.datetime.fromisoformat('0000W25')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    y = datetime.datetime.fromisoformat('0000W25')
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^
ValueError: month must be in 1..12

Same with 3.11.8 and 3.12.2.

[erlend-aasland]

I get the same results as Hugo on Ubuntu 24.04, Python 3.12.

[hugovk]

Also on 3.11-3.13 on Windows, macOS and Ubuntu on GitHub Actions:

• https://github.com/hugovk/test/actions/runs/8553089662

(3.8-3.10 also has a ValueError with a different error message.)

[Vlad4896]

It is interesting. I've just forked the repository, make and run my test.
I've used the following command to build Python:
./configure --with-pydebug && make -j8

After it I got the Assertion:
python: ./Modules/_datetimemodule.c:290: days_before_year: Assertion `year >= 1' failed.
Aborted (core dumped)

[erlend-aasland]

Could you try this, just to be sure:

$ git clean -fdx
$ ./configure --with-pydebug
$ make  # no -j8

[Eclips4]

Debug build on current main branch (clean build), macOS Sonoma 14.2.1:

./python.exe example.py                                
Assertion failed: (year >= 1), function days_before_year, file _datetimemodule.c, line 290.
zsh: abort      ./python.exe example.py

[Vlad4896]

I've tried as suggested Erlend and got the same result:
$ ./python mytest.py
python: ./Modules/_datetimemodule.c:290: days_before_year: Assertion `year >= 1' failed.
Aborted (core dumped)

I've the following back trace for this:

#1  __pthread_kill_internal (signo=6, threadid=140737352808256) at ./nptl/pthread_kill.c:78
#2  __GI___pthread_kill (threadid=140737352808256, signo=signo@entry=6) at ./nptl/pthread_kill.c:89
#3  0x00007ffff7c42476 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#4  0x00007ffff7c287f3 in __GI_abort () at ./stdlib/abort.c:79
#5  0x00007ffff7c2871b in __assert_fail_base (fmt=0x7ffff7ddd150 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x7ffff7e4e0e0 "year >= 1", 
    file=0x7ffff7e4e000 "./Modules/_datetimemodule.c", line=290, function=<optimized out>) at ./assert/assert.c:92
#6  0x00007ffff7c39e96 in __GI___assert_fail (assertion=assertion@entry=0x7ffff7e4e0e0 "year >= 1", file=file@entry=0x7ffff7e4e000 "./Modules/_datetimemodule.c", line=line@entry=290, 
    function=function@entry=0x7ffff7e50520 <__PRETTY_FUNCTION__.0> "days_before_year") at ./assert/assert.c:101
#7  0x00007ffff7e3d6bf in days_before_year (year=year@entry=0) at ./Modules/_datetimemodule.c:290
#8  0x00007ffff7e3d6d8 in ymd_to_ord (year=year@entry=0, month=month@entry=1, day=day@entry=1) at ./Modules/_datetimemodule.c:389
#9  0x00007ffff7e3d73b in iso_week1_monday (year=year@entry=0) at ./Modules/_datetimemodule.c:405
#10 0x00007ffff7e3d7d6 in iso_to_ymd (iso_year=0, iso_week=25, iso_day=1, year=year@entry=0x7fffffffd71c, month=month@entry=0x7fffffffd720, day=day@entry=0x7fffffffd724)
    at ./Modules/_datetimemodule.c:440
#11 0x00007ffff7e3d998 in parse_isoformat_date (dtstr=dtstr@entry=0x7ffff74dd328 "0000W25", len=len@entry=7, year=year@entry=0x7fffffffd71c, month=month@entry=0x7fffffffd720, 
    day=day@entry=0x7fffffffd724) at ./Modules/_datetimemodule.c:803
#12 0x00007ffff7e479c0 in datetime_fromisoformat (cls=0x7ffff7e58000 <PyDateTime_DateTimeType>, dtstr=0x7ffff74dd300) at ./Modules/_datetimemodule.c:5506
#13 0x00005555556f8c0b in cfunction_vectorcall_O (func=0x7ffff74d0ef0, args=<optimized out>, nargsf=<optimized out>, kwnames=<optimized out>) at Objects/methodobject.c:512
#14 0x000055555568692c in _PyObject_VectorcallTstate (tstate=0x555555c04510 <_PyRuntime+280656>, callable=0x7ffff74d0ef0, args=0x7ffff7fb0078, nargsf=9223372036854775809, kwnames=0x0)
    at ./Include/internal/pycore_call.h:168
#15 0x0000555555686a4b in PyObject_Vectorcall (callable=callable@entry=0x7ffff74d0ef0, args=args@entry=0x7ffff7fb0078, nargsf=<optimized out>, kwnames=kwnames@entry=0x0) at Objects/call.c:327
#16 0x00005555558124c1 in _PyEval_EvalFrameDefault (tstate=tstate@entry=0x555555c04510 <_PyRuntime+280656>, frame=0x7ffff7fb0020, throwflag=throwflag@entry=0) at Python/generated_cases.c.h:813
#17 0x0000555555834f71 in _PyEval_EvalFrame (throwflag=0, frame=<optimized out>, tstate=0x555555c04510 <_PyRuntime+280656>) at ./Include/internal/pycore_ceval.h:114
#18 _PyEval_Vector (tstate=tstate@entry=0x555555c04510 <_PyRuntime+280656>, func=func@entry=0x7ffff746a2d0, locals=locals@entry=0x7ffff74785f0, args=args@entry=0x0, argcount=argcount@entry=0, 
    kwnames=kwnames@entry=0x0) at Python/ceval.c:1807
#19 0x000055555583502f in PyEval_EvalCode (co=co@entry=0x7ffff75a2480, globals=globals@entry=0x7ffff74785f0, locals=locals@entry=0x7ffff74785f0) at Python/ceval.c:600
#20 0x00005555558bc6ae in run_eval_code_obj (tstate=tstate@entry=0x555555c04510 <_PyRuntime+280656>, co=co@entry=0x7ffff75a2480, globals=globals@entry=0x7ffff74785f0, 
    locals=locals@entry=0x7ffff74785f0) at Python/pythonrun.c:1291
#21 0x00005555558bdf7b in run_mod (mod=mod@entry=0x555555d32e28, filename=filename@entry=0x7ffff74a5ac0, globals=globals@entry=0x7ffff74785f0, locals=locals@entry=0x7ffff74785f0, 
    flags=flags@entry=0x7fffffffdc68, arena=arena@entry=0x7ffff74d0ca0, interactive_src=0x0, generate_new_source=0) at Python/pythonrun.c:1376
#22 0x00005555558be660 in pyrun_file (fp=fp@entry=0x555555cac010, filename=filename@entry=0x7ffff74a5ac0, start=start@entry=257, globals=globals@entry=0x7ffff74785f0, 
    locals=locals@entry=0x7ffff74785f0, closeit=closeit@entry=1, flags=0x7fffffffdc68) at Python/pythonrun.c:1212
#23 0x00005555558bf87d in _PyRun_SimpleFileObject (fp=fp@entry=0x555555cac010, filename=filename@entry=0x7ffff74a5ac0, closeit=closeit@entry=1, flags=flags@entry=0x7fffffffdc68)
    at Python/pythonrun.c:461
#24 0x00005555558bfb50 in _PyRun_AnyFileObject (fp=fp@entry=0x555555cac010, filename=filename@entry=0x7ffff74a5ac0, closeit=closeit@entry=1, flags=flags@entry=0x7fffffffdc68)
    at Python/pythonrun.c:77
#25 0x00005555558ea520 in pymain_run_file_obj (program_name=program_name@entry=0x7ffff74a5b40, filename=filename@entry=0x7ffff74a5ac0, skip_source_first_line=0) at Modules/main.c:357
#26 0x00005555558eb76b in pymain_run_file (config=config@entry=0x555555bd7438 <_PyRuntime+96120>) at Modules/main.c:376
#27 0x00005555558ebc45 in pymain_run_python (exitcode=exitcode@entry=0x7fffffffddf4) at Modules/main.c:628
--Type <RET> for more, q to quit, c to continue without paging-- 
#28 0x00005555558ebcb5 in Py_RunMain () at Modules/main.c:707
#29 0x00005555558ebd2c in pymain_main (args=args@entry=0x7fffffffde50) at Modules/main.c:737
#30 0x00005555558ebdef in Py_BytesMain (argc=<optimized out>, argv=<optimized out>) at Modules/main.c:761
#31 0x00005555555d48c6 in main (argc=<optimized out>, argv=<optimized out>) at ./Programs/python.c:15

[erlend-aasland]

I can reproduce on a fresh build on macOS. HEAD at b32789c.