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unpacker: fix silent datetime truncation with datetime=3 #701

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Merged
methane merged 2 commits into from
Jun 19, 2026
+14 −1
Merged

unpacker: fix silent datetime truncation with datetime=3 #701

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unpacker: fix silent datetime truncation with datetime=3
methane Jun 19, 2026
58bbd08
fix comment
methane Jun 19, 2026
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9 changes: 8 additions & 1 deletion msgpack/unpack.h
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Original file line number Diff line number Diff line change
Expand Up @@ -283,6 +283,7 @@ static int unpack_timestamp(const char* buf, unsigned int buflen, msgpack_timest
ts->tv_sec = _msgpack_load64(int64_t, buf + 4);
return 0;
default:
PyErr_Format(PyExc_ValueError, "invalid timestamp data (length %u)", buflen);
return -1;
}
}
Expand Down Expand Up @@ -336,12 +337,18 @@ static int unpack_callback_ext(unpack_user* u, const char* base, const char* pos
else if (u->timestamp == 3) { // datetime
// Calculate datetime using epoch + delta
// due to limitations PyDateTime_FromTimestamp on Windows with negative timestamps
int64_t days = ts.tv_sec / (24*3600);
if (days < INT_MIN || days > INT_MAX) {
PyErr_Format(PyExc_OverflowError,
"days=%lld; too large to convert to C int", days);
return -1;
}
PyObject *epoch = PyDateTimeAPI->DateTime_FromDateAndTime(1970, 1, 1, 0, 0, 0, 0, u->utc, PyDateTimeAPI->DateTimeType);
if (epoch == NULL) {
return -1;
}

PyObject* d = PyDelta_FromDSU(ts.tv_sec/(24*3600), ts.tv_sec%(24*3600), ts.tv_nsec / 1000);
PyObject* d = PyDelta_FromDSU((int)days, ts.tv_sec%(24*3600), ts.tv_nsec / 1000);
if (d == NULL) {
Py_DECREF(epoch);
return -1;
Expand Down
6 changes: 6 additions & 0 deletions test/test_timestamp.py
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Expand Up @@ -176,3 +176,9 @@ def test_pack_datetime_without_tzinfo():
packed = msgpack.packb(dt, datetime=True)
unpacked = msgpack.unpackb(packed, timestamp=3)
assert unpacked == dt


def test_too_large_timestamp():
# When timestamp64 is too large, conversion to datetime fails due to int64 -> int32 conversion.
# https://github.com/msgpack/msgpack-python/issues/696
print(msgpack.unpackb(b"\xd7\xff" + b"\x00" * 8, timestamp=3))
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