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@roose roose/mozlz4a.py forked from Tblue/mozlz4a.py
Created Apr 11, 2016

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MozLz4a compression/decompression utility
#!/usr/bin/env python
#
# Decompressor/compressor for files in Mozilla's "mozLz4" format. Firefox uses this file format to
# compress e. g. bookmark backups (*.jsonlz4).
#
# This file format is in fact just plain LZ4 data with a custom header (magic number [8 bytes] and
# uncompressed file size [4 bytes, little endian]).
#
# This Python 3 script requires the LZ4 bindings for Python, see: https://pypi.python.org/pypi/lz4
#
#
# Copyright (c) 2015, Tilman Blumenbach
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification, are permitted
# provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this list of conditions
# and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice, this list of
# conditions and the following disclaimer in the documentation and/or other materials provided
# with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
# FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
# IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import lz4ext
import sys
from argparse import ArgumentParser
class MozLz4aError(Exception):
pass
class InvalidHeader(MozLz4aError):
def __init__(self, msg):
self.msg = msg
def __str__(self):
return self.msg
def decompress(file_obj):
if file_obj.read(8) != b"mozLz40\0":
raise InvalidHeader("Invalid magic number")
return lz4.decompress(file_obj.read())
def compress(file_obj):
compressed = lz4.compress(file_obj.read())
return b"mozLz40\0" + compressed
if __name__ == "__main__":
argparser = ArgumentParser(description="MozLz4a compression/decompression utility")
argparser.add_argument(
"-d", "--decompress", "--uncompress",
action="store_true",
help="Decompress the input file instead of compressing it."
)
argparser.add_argument(
"in_file",
help="Path to input file."
)
argparser.add_argument(
"out_file",
help="Path to output file."
)
parsed_args = argparser.parse_args()
try:
in_file = open(parsed_args.in_file, "rb")
except IOError as e:
print("Could not open input file `%s' for reading: %s" % (parsed_args.in_file, e), file=sys.stderr)
sys.exit(2)
try:
out_file = open(parsed_args.out_file, "wb")
except IOError as e:
print("Could not open output file `%s' for writing: %s" % (parsed_args.out_file, e), file=sys.stderr)
sys.exit(3)
try:
if parsed_args.decompress:
data = decompress(in_file)
else:
data = compress(in_file)
except Exception as e:
print("Could not compress/decompress file `%s': %s" % (parsed_args.in_file, e), file=sys.stderr)
sys.exit(4)
try:
out_file.write(data)
except IOError as e:
print("Could not write to output file `%s': %s" % (parsed_args.out_file, e), file=sys.stderr)
sys.exit(5)
finally:
out_file.close()
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