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Fix and optimize _scan_data_descriptor_no_sig

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This commit is contained in:
Danny Lin 2025-06-01 11:14:19 +08:00
parent 8067b0c489
commit 92d3a9c418
1 changed files with 8 additions and 10 deletions
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18
Lib/zipfile/__init__.py
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@ -1712,30 +1712,28 @@ def _scan_data_descriptor_no_sig(self, fp, offset, end_offset, zip64, chunk_size
dd_fmt = '<LQQ' if zip64 else '<LLL' dd_fmt = '<LQQ' if zip64 else '<LLL'
dd_size = struct.calcsize(dd_fmt) dd_size = struct.calcsize(dd_fmt)
base = offset pos = offset
remainder = b'' remainder = b''
while base < end_offset: fp.seek(offset)
fp.seek(base) while pos < end_offset:
chunk = remainder + fp.read(min(chunk_size, end_offset - base)) chunk = remainder + fp.read(min(chunk_size, end_offset - pos))
if not chunk:
break
scan_limit = len(chunk) - dd_size + 1 delta = pos - len(remainder) - offset
mv = memoryview(chunk) mv = memoryview(chunk)
for i in range(scan_limit): for i in range(len(chunk) - dd_size + 1):
dd = mv[i:i + dd_size] dd = mv[i:i + dd_size]
try: try:
crc, compress_size, file_size = struct.unpack(dd_fmt, dd) crc, compress_size, file_size = struct.unpack(dd_fmt, dd)
except struct.error: except struct.error:
continue continue
if (base + i) - offset != compress_size: if delta + i != compress_size:
continue continue
return crc, compress_size, file_size, dd_size return crc, compress_size, file_size, dd_size
remainder = chunk[-(dd_size - 1):] remainder = chunk[-(dd_size - 1):]
base += scan_limit pos += chunk_size
return None return None