_zoneinfo: get_local_timestamp() misinterprets valid -1 results from PyLong_AsLong()

[BHUVANSH855]

Bug report

Bug description:

Modules/_zoneinfo.c:get_local_timestamp() incorrectly treats the valid integer value -1 returned by PyLong_AsLong() as an error for the hour, minute, and second fields.

PyLong_AsLong() returns -1 both on conversion failure and for the legitimate Python integer -1. The C API requires checking PyErr_Occurred() to distinguish these cases.

The function already does this correctly for toordinal():

ord = PyLong_AsLong(num);
if (ord == -1 && PyErr_Occurred()) {
    return -1;
}

However, the checks for hour, minute, and second only test == -1:

hour = PyLong_AsLong(num);
if (hour == -1) {
    return -1;
}

minute = PyLong_AsLong(num);
if (minute == -1) {
    return -1;
}

second = PyLong_AsLong(num);
if (second == -1) {
    return -1;
}

As a result, valid values of -1 are incorrectly treated as conversion failures, causing the function to return an error without an exception being set.

Reproducer

from datetime import datetime
from zoneinfo import ZoneInfo

class BadDateTime(datetime):
    @property
    def hour(self):
        return -1

dt = BadDateTime(2024, 1, 1, tzinfo=ZoneInfo("UTC"))
dt.utcoffset()

Current behavior:

SystemError: <method 'utcoffset' of 'zoneinfo.ZoneInfo' objects> returned NULL without setting an exception

The same issue also affects:

• ZoneInfo.dst()
• ZoneInfo.tzname()
• ZoneInfo.fromutc()

The issue reproduces on the current main branch on Linux.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

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

[zangjiucheng]

IIUC, we can add&& PyErr_Occurred() at the three sites to restore parity with the pure-Python implementation.

- if (second == -1)
+ if (second == -1 && PyErr_Occurred())

cpython/Modules/_zoneinfo.c

Lines 2312 to 2336 in 449122e

	hour = PyLong_AsLong(num);
	Py_DECREF(num);
	if (hour == -1) {
	return -1;
	}
	num = PyObject_GetAttrString(dt, "minute");
	if (num == NULL) {
	return -1;
	}
	minute = PyLong_AsLong(num);
	Py_DECREF(num);
	if (minute == -1) {
	return -1;
	}
	num = PyObject_GetAttrString(dt, "second");
	if (num == NULL) {
	return -1;
	}
	second = PyLong_AsLong(num);
	Py_DECREF(num);
	if (second == -1) {
	return -1;
	}

btw this has been present since _zoneinfo.c was added in 3.9; backtrack to the commit (62972d9d73e), so 3.13 and 3.14 are affected too.