Skip to content

Fix zlib parsing of length for large uncompressed block #100

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Jan 6, 2025
Merged

Fix zlib parsing of length for large uncompressed block #100

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
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
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 4 additions & 4 deletions hachoir/parser/archive/zlib.py
View file
Open in desktop
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)
Expand Down
Binary file added tests/files/usa_railroad.jpg.0.zlib
View file
Open in desktop
Binary file not shown.
Binary file added tests/files/usa_railroad.jpg.6.zlib
View file
Open in desktop
Binary file not shown.
31 changes: 31 additions & 0 deletions tests/test_parser.py
View file
Open in desktop
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
Loading