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Fix zlib parsing of length for large uncompressed block #100

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merged 3 commits into from
Jan 6, 2025
Merged

Fix zlib parsing of length for large uncompressed block #100

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070026c
zlib: add basic tests
oliver Jan 4, 2025
b5ade80
zlib: add test for uncompressed data with block size > 32K
oliver Jan 4, 2025
e038afe
zlib: fix length parsing for uncompressed data
oliver Jan 4, 2025
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8 changes: 4 additions & 4 deletions hachoir/parser/archive/zlib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@
"""

from hachoir.parser import Parser
from hachoir.field import (Bit, Bits, Field, Int16, UInt32,
from hachoir.field import (Bit, Bits, Field, UInt16, UInt32,
Enum, FieldSet, GenericFieldSet,
PaddingBits, ParserError, RawBytes)
from hachoir.core.endian import LITTLE_ENDIAN
Expand Down Expand Up @@ -149,9 +149,9 @@ def createFields(self):
padding = paddingSize(self.current_size + self.absolute_address, 8)
if padding:
yield PaddingBits(self, "padding[]", padding)
yield Int16(self, "len")
yield Int16(self, "nlen", "One's complement of len")
if self["len"].value != ~self["nlen"].value:
yield UInt16(self, "len")
yield UInt16(self, "nlen", "One's complement of len")
if self["len"].value != ((~self["nlen"].value) & 0xFFFF):
raise ParserError(
"len must be equal to the one's complement of nlen!")
# null stored blocks produced by some encoders (e.g. PIL)
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Binary file added tests/files/usa_railroad.jpg.0.zlib
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Binary file added tests/files/usa_railroad.jpg.6.zlib
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31 changes: 31 additions & 0 deletions tests/test_parser.py
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Original file line number Diff line number Diff line change
Expand Up @@ -883,6 +883,37 @@ def test_arj2(self):
self.checkValue(parser, "/file_header[15]/filename", "usr/bin/groups")
self.checkValue(parser, "/file_header[15]/original_size", 35000)

def test_zlib(self):
parser = self.parse("usa_railroad.jpg.6.zlib")
self.checkValue(parser, "/compression_method", 8)
self.checkValue(parser, "/compression_info", 7)
self.checkValue(parser, "/flag_check_bits", 30)
self.checkValue(parser, "/flag_dictionary_present", False)
self.checkValue(parser, "/flag_compression_level", 1)
self.checkValue(parser, "/data/compressed_block[0]/final", False)
self.checkValue(parser, "/data/compressed_block[0]/compression_type", 2)
self.checkValue(parser, "/data/compressed_block[0]/huff_num_length_codes", 29)
self.checkValue(parser, "/data/compressed_block[0]/length_code[16383]", 16380)
self.checkValue(parser, "/data/compressed_block[5]/final", True)
self.checkValue(parser, "/data/compressed_block[5]/compression_type", 0)
self.checkValue(parser, "/data/compressed_block[5]/len", 8844)
self.checkValue(parser, "/data/compressed_block[5]/nlen", 56691)
self.checkValue(parser, "/data_checksum", 0xe85c1f89)

def test_zlib_large_uncompressed_block(self):
parser = self.parse("usa_railroad.jpg.0.zlib")
self.checkValue(parser, "/data/compressed_block[0]/final", False)
self.checkValue(parser, "/data/compressed_block[0]/compression_type", 0)
self.checkValue(parser, "/data/compressed_block[0]/padding[0]", 0)
self.checkValue(parser, "/data/compressed_block[0]/len", 65535)
self.checkValue(parser, "/data/compressed_block[0]/nlen", 0)
self.checkValue(parser, "/data/compressed_block[1]/final", True)
self.checkValue(parser, "/data/compressed_block[1]/compression_type", 0)
self.checkValue(parser, "/data/compressed_block[1]/padding[0]", 0)
self.checkValue(parser, "/data/compressed_block[1]/len", 38213)
self.checkValue(parser, "/data/compressed_block[1]/nlen", 27322)
self.checkValue(parser, "/data_checksum", 0xe85c1f89)


class TestParserRandomStream(unittest.TestCase):

Expand Down
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