Tblue · November 16, 2025 16:46 · drelephant · Sep 19, 2024 · gitcos · Nov 16, 2025
diff --git a/mozlz4a.py b/mozlz4a.py
 #!/usr/bin/env python3
 # vim: sw=4 ts=4 et tw=100 cc=+1
 #
 ####################################################################################################
 #                                           DESCRIPTION                                            #
 ####################################################################################################
 #
 # 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]).
 #
 ####################################################################################################
 #                                           DEPENDENCIES                                           #
 ####################################################################################################
 #
 # - Tested with Python 3.10
 # - LZ4 bindings for Python, version 4.x: https://pypi.python.org/pypi/lz4
 #
 ####################################################################################################
 #                                             LICENSE                                              #
 ####################################################################################################
 #
 # Copyright (c) 2015-2022, 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 argparse
 import sys

 import lz4.block


 class BinFileArg:
    def __init__(self, mode):
        self._mode = mode

    def __call__(self, arg):
        objs = {
            "r": sys.stdin.buffer,
            "w": sys.stdout.buffer,
        }

        if arg == "-":
            return objs[self._mode]

        try:
            return open(arg, self._mode + "b")
        except OSError as e:
            raise argparse.ArgumentTypeError(
                "failed to open file for %s: %s" % (
                    "reading" if self._mode == "r" else "writing",
                    e
                )
            )


 def decompress(file_obj):
    if file_obj.read(8) != b"mozLz40\0":
        raise ValueError("Invalid magic number")

    return lz4.block.decompress(file_obj.read())


 def compress(file_obj):
    compressed = lz4.block.compress(file_obj.read())
    return b"mozLz40\0" + compressed


 def get_argparser():
    p = argparse.ArgumentParser(
        description="MozLz4a compression/decompression utility"
    )

    p.add_argument(
        "-d", "--decompress", "--uncompress",
        action="store_true",
        help="Decompress the input file instead of compressing it."
    )

    p.add_argument(
        "in_file",
        type=BinFileArg("r"),
        help="Path to input file. `-' means standard input."
    )
    p.add_argument(
        "out_file",
        type=BinFileArg("w"),
        nargs="?",
        default="-",
        help="Path to output file. `-' means standard output (and is the default)."
    )

    return p


 def main():
    args = get_argparser().parse_args()

    try:
        with args.in_file as fh:
            if args.decompress:
                data = decompress(fh)
            else:
                data = compress(fh)
    except Exception as e:
        print(
            "Could not compress/decompress file `%s': %s" % (
                args.in_file.name,
                e
            ),
            file=sys.stderr
        )
        sys.exit(4)

    try:
        with args.out_file as fh:
            fh.write(data)
    except Exception as e:
        print(
            "Could not write to output file `%s': %s" % (
                args.out_file.name,
                e
            ),
            file=sys.stderr
        )
        sys.exit(5)


 if __name__ == "__main__":
    sys.exit(main())
	#!/usr/bin/env python3
	# vim: sw=4 ts=4 et tw=100 cc=+1
	#
	####################################################################################################
	# DESCRIPTION #
	####################################################################################################
	#
	# 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]).
	#
	####################################################################################################
	# DEPENDENCIES #
	####################################################################################################
	#
	# - Tested with Python 3.10
	# - LZ4 bindings for Python, version 4.x: https://pypi.python.org/pypi/lz4
	#
	####################################################################################################
	# LICENSE #
	####################################################################################################
	#
	# Copyright (c) 2015-2022, 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 argparse
	import sys

	import lz4.block


	class BinFileArg:
	def __init__(self, mode):
	self._mode = mode

	def __call__(self, arg):
	objs = {
	"r": sys.stdin.buffer,
	"w": sys.stdout.buffer,
	}

	if arg == "-":
	return objs[self._mode]

	try:
	return open(arg, self._mode + "b")
	except OSError as e:
	raise argparse.ArgumentTypeError(
	"failed to open file for %s: %s" % (
	"reading" if self._mode == "r" else "writing",
	e
	)
	)


	def decompress(file_obj):
	if file_obj.read(8) != b"mozLz40\0":
	raise ValueError("Invalid magic number")

	return lz4.block.decompress(file_obj.read())


	def compress(file_obj):
	compressed = lz4.block.compress(file_obj.read())
	return b"mozLz40\0" + compressed


	def get_argparser():
	p = argparse.ArgumentParser(
	description="MozLz4a compression/decompression utility"
	)

	p.add_argument(
	"-d", "--decompress", "--uncompress",
	action="store_true",
	help="Decompress the input file instead of compressing it."
	)

	p.add_argument(
	"in_file",
	type=BinFileArg("r"),
	help="Path to input file. `-' means standard input."
	)
	p.add_argument(
	"out_file",
	type=BinFileArg("w"),
	nargs="?",
	default="-",
	help="Path to output file. `-' means standard output (and is the default)."
	)

	return p


	def main():
	args = get_argparser().parse_args()

	try:
	with args.in_file as fh:
	if args.decompress:
	data = decompress(fh)
	else:
	data = compress(fh)
	except Exception as e:
	print(
	"Could not compress/decompress file `%s': %s" % (
	args.in_file.name,
	e
	),
	file=sys.stderr
	)
	sys.exit(4)

	try:
	with args.out_file as fh:
	fh.write(data)
	except Exception as e:
	print(
	"Could not write to output file `%s': %s" % (
	args.out_file.name,
	e
	),
	file=sys.stderr
	)
	sys.exit(5)


	if __name__ == "__main__":
	sys.exit(main())
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