Skip to content

gh-154892: Fix PyLong_AsLong() error checks in _zoneinfo #154901

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
BHUVANSH855 wants to merge 4 commits into
base: main
Choose a base branch
from
+32 −3
Open

gh-154892: Fix PyLong_AsLong() error checks in _zoneinfo #154901

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
f8bbeac
gh-154892: Fix PyLong_AsLong() error checks in _zoneinfo
BHUVANSH855 Jul 29, 2026
683a1d4
gh-154892: Move regression test to ZoneInfoTest
BHUVANSH855 Jul 30, 2026
31914db
Address review comments
BHUVANSH855 Jul 30, 2026
dfaec03
Update NEWS entry
BHUVANSH855 Jul 30, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 26 additions & 0 deletions Lib/test/test_zoneinfo/test_zoneinfo.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -316,6 +316,32 @@ def test_unambiguous(self):
self.assertEqual(dt.utcoffset(), offset.utcoffset, dt)
self.assertEqual(dt.dst(), offset.dst, dt)

def test_datetime_subclass_negative_components(self):
# Regression test for gh-154892.
class MinusOneDateTime(datetime):
@property
def hour(self):
return -1

@property
def minute(self):
return -1

@property
def second(self):
return -1

zi = self.zone_from_key("UTC")
dt = MinusOneDateTime(2024, 1, 1, tzinfo=zi)

self.assertEqual(dt.utcoffset(), ZERO)
self.assertEqual(dt.dst(), ZERO)
self.assertEqual(dt.tzname(), "UTC")
self.assertEqual(
zi.fromutc(dt),
datetime(2024, 1, 1, tzinfo=zi),
)

def test_folds_and_gaps(self):
test_cases = []
for key in self.zones():
Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2026-07-29-21-37-39.gh-issue-154892.eQyJ3Z.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix a bug in the C accelerator for :mod:`zoneinfo` where
:class:`datetime.datetime` subclasses returning ``-1`` for ``hour``,
``minute``, or ``second`` could incorrectly raise a :exc:`SystemError`.
6 changes: 3 additions & 3 deletions Modules/_zoneinfo.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2311,7 +2311,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
}
hour = PyLong_AsLong(num);

@eendebakpt eendebakpt Jul 29, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Not exactly the issue, but related. What if a subclass returns 2**40? Maybe PyLong_AsInt can be used.

@BHUVANSH855 BHUVANSH855 Jul 30, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

That's a good point. I hadn't considered oversized integer values like 2**40. Since this PR is focused on fixing the -1 sentinel handling from PyLong_AsLong(), I'd prefer to keep that as a separate change if we decide PyLong_AsInt() is the better choice.

@eendebakpt eendebakpt Jul 30, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ok. Could you open an issue for this so we do not forget?

@BHUVANSH855 BHUVANSH855 Jul 30, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Sure, I'll investigate this further and open a separate issue to track it so it doesn't get lost.

@BHUVANSH855 BHUVANSH855 Jul 30, 2026

Copy link
Copy Markdown
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks for pointing this out! I investigated it further.

The C implementation currently uses PyObject_GetAttrString() + PyLong_AsLong() for datetime subclasses, but the pure Python implementation follows the same approach:

(dt.toordinal() - EPOCHORDINAL) * 86400 + dt.hour * 3600 + dt.minute * 60 + dt.second

So both implementations intentionally consult the subclass-visible hour, minute, and second attributes.

I also tested subclasses returning very large values (e.g. 10**12), and both the C and pure Python implementations behave the same way. This means switching to PyLong_AsInt() in the C implementation would only narrow the accepted range there, while the pure Python implementation would continue to accept arbitrarily large values, resulting in inconsistent behavior between the two implementations.

It seems the underlying question is whether ZoneInfo should be consulting overridden subclass attributes at all, rather than whether PyLong_AsLong() should be replaced with PyLong_AsInt().

Py_DECREF(num);
if (hour == -1) {
if (hour == -1 && PyErr_Occurred()) {
return -1;
}

Expand All @@ -2321,7 +2321,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
}
minute = PyLong_AsLong(num);
Py_DECREF(num);
if (minute == -1) {
if (minute == -1 && PyErr_Occurred()) {
return -1;
}

Expand All @@ -2331,7 +2331,7 @@ get_local_timestamp(PyObject *dt, int64_t *local_ts)
}
second = PyLong_AsLong(num);
Py_DECREF(num);
if (second == -1) {
if (second == -1 && PyErr_Occurred()) {
return -1;
}
}
Expand Down
Loading