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Blackrock: fix OverflowError reading .nev files over 4 GiB #1929

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Blackrock: fix OverflowError reading .nev files over 4 GiB #1929

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5 changes: 3 additions & 2 deletions neo/rawio/blackrockrawio.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1683,7 +1683,8 @@ def _read_nev_data(self, spec, filename):
The NEV filename to read from
"""
packet_size_bytes = self._nev_basic_header["bytes_in_data_packets"]
header_size = self._nev_basic_header["bytes_in_headers"]
# int(): a uint32 scalar overflows against file sizes > 4 GiB under NumPy 2 (NEP 50)
header_size = int(self._nev_basic_header["bytes_in_headers"])

if self._nev_basic_header["ver_major"] >= 3:
ts_format = "uint64"
Expand Down Expand Up @@ -1995,7 +1996,7 @@ def _get_nev_rec_times(self):
filename = ".".join([self._filenames["nev"], "nev"])

dt = [("timestamp", "uint32")]
offset = self._get_file_size(filename) - self._nev_params("bytes_in_data_packets")
offset = self._get_file_size(filename) - int(self._nev_params("bytes_in_data_packets"))
last_data_packet = np.memmap(filename, offset=offset, dtype=dt, mode="r")[0]

n_starts = [0 * self._nev_params("event_unit")]
Expand Down
32 changes: 32 additions & 0 deletions neo/test/rawiotest/test_blackrockrawio.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
"""

import unittest
from unittest import mock

from neo.rawio.blackrockrawio import BlackrockRawIO
from neo.test.rawiotest.common_rawio_test import BaseTestRawIO
Expand Down Expand Up @@ -374,6 +375,37 @@ def test_gap_tolerance_ms_parameter(self):
segments_strict = reader_strict.segment_count(0)
self.assertEqual(segments_strict, 3) #

def test_nev_over_4_gib_does_not_overflow(self):
"""File sizes > 4 GiB must not overflow against the uint32 NEV header fields (NumPy 2, NEP 50)."""
file_size = 5 * 2**30
basic_header = np.zeros(
1, dtype=[("ver_major", "uint8"), ("bytes_in_headers", "uint32"), ("bytes_in_data_packets", "uint32")]
)[0]
basic_header["ver_major"] = 2
basic_header["bytes_in_headers"] = 1000
basic_header["bytes_in_data_packets"] = 104

reader = BlackrockRawIO.__new__(BlackrockRawIO) # skip parsing real files
reader._nev_basic_header = basic_header
reader._nev_params = lambda name: basic_header[name]
reader._filenames = {"nev": "fake"}

class Stop(Exception):
pass

with (
mock.patch.object(reader, "_get_file_size", return_value=file_size),
mock.patch("neo.rawio.blackrockrawio.np.memmap", side_effect=Stop) as memmap,
):
with self.assertRaises(Stop):
reader._read_nev_data("2.2", "fake.nev")
self.assertEqual(memmap.call_args.kwargs["offset"], 1000)
self.assertEqual(memmap.call_args.kwargs["shape"], ((file_size - 1000) // 104,))

with self.assertRaises(Stop):
reader._get_nev_rec_times()
self.assertEqual(memmap.call_args.kwargs["offset"], file_size - 104)


if __name__ == "__main__":
unittest.main()
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