Allow reading files with invalid dates

Notably, KLayout writes invalid dates when told to not write the date

klamath/basic.py

@@ -3,12 +3,16 @@ Functionality for encoding/decoding basic datatypes
 """
 from typing import Sequence, IO
 import struct
+import logging
 from datetime import datetime
 
 import numpy
 from numpy.typing import NDArray
 
 
+logger = logging.getLogger(__name__)
+
+
 class KlamathError(Exception):
     pass
 
@@ -44,7 +48,7 @@ def decode_real8(nums: NDArray[numpy.uint64]) -> NDArray[numpy.float64]:
     exp = (nums >> 56) & 0x7f
     mant = (nums & 0x00ff_ffff_ffff_ffff).astype(numpy.float64)
     mant[neg != 0] *= -1
-    return numpy.ldexp(mant, (4 * (exp - 64) - 56).astype(numpy.int64))
+    return numpy.ldexp(mant, 4 * (exp - 64) - 56, signature=(float, int, float))
 
 
 def parse_real8(data: bytes) -> NDArray[numpy.float64]:
@@ -70,7 +74,12 @@ def parse_datetime(data: bytes) -> list[datetime]:
     dts = []
     for ii in range(0, len(data), 12):
         year, *date_parts = parse_int2(data[ii:ii + 12])
-        dts.append(datetime(year + 1900, *date_parts))
+        try:
+            dt = datetime(year + 1900, *date_parts)
+        except ValueError as err:
+            dt = datetime(1900, 1, 1, 0, 0, 0)
+            logger.warning(f'Invalid date {[year] + date_parts}, setting {dt} instead')
+        dts.append(dt)
     return dts
 
 

klamath/test_basic.py

@@ -2,11 +2,12 @@ import struct
 
 import pytest       # type: ignore
 import numpy
+from datetime import datetime
 from numpy.testing import assert_array_equal
 
 from .basic import parse_bitarray, parse_int2, parse_int4, parse_real8, parse_ascii
 from .basic import pack_bitarray, pack_int2, pack_int4, pack_real8, pack_ascii
-from .basic import decode_real8, encode_real8
+from .basic import decode_real8, encode_real8, parse_datetime
 
 from .basic import KlamathError
 
@@ -117,3 +118,14 @@ def test_pack_real8():
 def test_pack_ascii():
     assert pack_ascii(b'4321') == b'4321'
     assert pack_ascii(b'321') == b'321\0'
+
+
+def test_invalid_date():
+    default = [datetime(1900, 1, 1, 0, 0, 0)]
+    assert parse_datetime(pack_int2((0, 0, 0, 0, 0, 0))) == default
+    assert parse_datetime(pack_int2((0, 1, 32, 0, 0, 0))) == default
+    assert parse_datetime(pack_int2((0, 2, 30, 0, 0, 0))) == default
+    assert parse_datetime(pack_int2((0, 1, 1, 24, 0, 0))) == default
+    assert parse_datetime(pack_int2((0, 1, 1, 25, 0, 0))) == default
+    assert parse_datetime(pack_int2((0, 1, 1, 0, 61, 0))) == default
+    assert parse_datetime(pack_int2((0, 1, 1, 0,  0, 61))) == default