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bpo-38256: Fix binascii.crc32() when inputs are 4+GiB (GH-32000)

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When compiled with `USE_ZLIB_CRC32` defined (`configure` sets this on POSIX systems), `binascii.crc32(...)` failed to compute the correct value when the input data was >= 4GiB. Because the zlib crc32 API is limited to a 32-bit length.

This lines it up with the `zlib.crc32(...)` implementation that doesn't have that flaw.

**Performance:** This also adopts the same GIL releasing for larger inputs logic that `zlib.crc32` has, and causes the Windows build to always use zlib's crc32 instead of our slow C code as zlib is a required build dependency on Windows.
This commit is contained in:
Gregory P. Smith 2022-03-20 12:28:15 -07:00 • committed by GitHub
parent 3ae975f1ac
commit 9d1c4d69db
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6 changed files with 87 additions and 31 deletions
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10
Lib/test/test_binascii.py
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@ -4,7 +4,7 @@ import unittest
import binascii
import array
import re
from test.support import warnings_helper
from test.support import bigmemtest, _1G, _4G, warnings_helper
# Note: "*_hex" functions are aliases for "(un)hexlify"
@ -441,6 +441,14 @@ class BytearrayBinASCIITest(BinASCIITest):
class MemoryviewBinASCIITest(BinASCIITest):
type2test = memoryview
class ChecksumBigBufferTestCase(unittest.TestCase):
"""bpo-38256 - check that inputs >=4 GiB are handled correctly."""
@bigmemtest(size=_4G + 4, memuse=1, dry_run=False)
def test_big_buffer(self, size):
data = b"nyan" * (_1G + 1)
self.assertEqual(binascii.crc32(data), 1044521549)
if __name__ == "__main__":
unittest.main()