fix: handle OverflowError in timestamp fallbacks

Author: parinporecha

src/pendulum/__init__.py

@@ -288,11 +288,7 @@ def from_timestamp(timestamp: int | float, tz: str | Timezone = UTC) -> DateTime
     """
     try:
         dt = _datetime.datetime.fromtimestamp(timestamp, tz=UTC)
-    except OSError:
-        # On some platforms (notably Windows), datetime.fromtimestamp
-        # raises OSError for negative timestamps that are too far from
-        # the Unix epoch.  Fall back to computing the result from the
-        # epoch and applying the offset manually.
+    except (OSError, OverflowError):
         epoch = _datetime.datetime(1970, 1, 1, tzinfo=UTC)
         dt = epoch + _datetime.timedelta(seconds=timestamp)
 

src/pendulum/datetime.py

@@ -1255,7 +1255,7 @@ def fromtimestamp(cls, t: float, tz: datetime.tzinfo | None = None) -> Self:
 
         try:
             dt = datetime.datetime.fromtimestamp(t, tz=tzinfo)
-        except OSError:
+        except (OSError, OverflowError):
             dt = (cls._EPOCH + datetime.timedelta(seconds=t)).astimezone(tzinfo)
 
         return cls.instance(dt, tz=tzinfo)
@@ -1264,7 +1264,9 @@ def fromtimestamp(cls, t: float, tz: datetime.tzinfo | None = None) -> Self:
     def utcfromtimestamp(cls, t: float) -> Self:
         try:
             dt = datetime.datetime.utcfromtimestamp(t)
-        except OSError:
+        except (OSError, OverflowError):
+            # Match datetime.datetime.utcfromtimestamp(), which returns a
+            # naive datetime representing UTC.
             dt = datetime.datetime(1970, 1, 1) + datetime.timedelta(seconds=t)
 
         return cls.instance(dt, tz=None)

tests/datetime/test_behavior.py

@@ -6,6 +6,8 @@
 import types
 import zoneinfo
 
+import pytest
+
 from copy import deepcopy
 from datetime import date
 from datetime import datetime
@@ -110,14 +112,15 @@ def test_utcfromtimestamp():
     assert p == dt
 
 
-def test_fromtimestamp_falls_back_for_negative_timestamp(monkeypatch):
+@pytest.mark.parametrize("exception_type", [OSError, OverflowError])
+def test_fromtimestamp_falls_back_for_negative_timestamp(monkeypatch, exception_type):
     pendulum_datetime_module = importlib.import_module("pendulum.datetime")
 
     class FakeDateTime(datetime_.datetime):
         @classmethod
         def fromtimestamp(cls, t: float, tz: datetime_.tzinfo | None = None):
             if t == -43201:
-                raise OSError("Invalid argument")
+                raise exception_type("Invalid argument")
 
             return super().fromtimestamp(t, tz=tz)
 
@@ -133,14 +136,15 @@ def fromtimestamp(cls, t: float, tz: datetime_.tzinfo | None = None):
     assert p.timezone_name == "UTC"
 
 
-def test_utcfromtimestamp_falls_back_for_negative_timestamp(monkeypatch):
+@pytest.mark.parametrize("exception_type", [OSError, OverflowError])
+def test_utcfromtimestamp_falls_back_for_negative_timestamp(monkeypatch, exception_type):
     pendulum_datetime_module = importlib.import_module("pendulum.datetime")
 
     class FakeDateTime(datetime_.datetime):
         @classmethod
         def utcfromtimestamp(cls, t: float):
             if t == -43201:
-                raise OSError("Invalid argument")
+                raise exception_type("Invalid argument")
 
             return super().utcfromtimestamp(t)
 

tests/datetime/test_create_from_timestamp.py

@@ -1,6 +1,9 @@
 from __future__ import annotations
 
+import datetime as datetime_
+
 import pendulum
+import pytest
 
 from pendulum import timezone
 from tests.conftest import assert_datetime
@@ -25,28 +28,38 @@ def test_create_from_timestamp_with_timezone():
 
 
 def test_create_from_timestamp_negative():
-    """Negative timestamps earlier than 12h before the Unix epoch should work.
-
-    Regression test for issue 956: on Windows (and potentially other
-    platforms), datetime.fromtimestamp raises OSError for timestamps
-    below a platform-specific minimum.  pendulum should still return a
-    correct DateTime.
-    """
-    # -43201 is 1 second past the 12h-before-epoch boundary reported in the issue
     d = pendulum.from_timestamp(-43201)
     assert_datetime(d, 1969, 12, 31, 11, 59, 59)
     assert d.timezone_name == "UTC"
 
 
 def test_create_from_timestamp_negative_with_timezone():
-    """Negative timestamps with an explicit timezone should also work."""
     d = pendulum.from_timestamp(-43201, "America/Toronto")
     assert d.timezone_name == "America/Toronto"
     assert_datetime(d, 1969, 12, 31, 6, 59, 59)
 
 
 def test_create_from_timestamp_negative_with_microseconds():
-    """Negative float timestamps preserving microseconds."""
     d = pendulum.from_timestamp(-43201.5)
     assert_datetime(d, 1969, 12, 31, 11, 59, 58, 500000)
     assert d.timezone_name == "UTC"
+
+
+@pytest.mark.parametrize("exception_type", [OSError, OverflowError])
+def test_create_from_timestamp_falls_back_for_negative_timestamp(
+    monkeypatch, exception_type
+):
+    class FakeDateTime(datetime_.datetime):
+        @classmethod
+        def fromtimestamp(cls, timestamp: float, tz: datetime_.tzinfo | None = None):
+            if timestamp == -43201:
+                raise exception_type("Invalid argument")
+
+            return super().fromtimestamp(timestamp, tz=tz)
+
+    monkeypatch.setattr(pendulum._datetime, "datetime", FakeDateTime)
+
+    d = pendulum.from_timestamp(-43201)
+
+    assert_datetime(d, 1969, 12, 31, 11, 59, 59)
+    assert d.timezone_name == "UTC"