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# SPDX-License-Identifier: GPL-2.0+
# Copyright 2022 Google LLC
#
"""Utilities to compress and decompress data"""
import struct
import tempfile
from binman import bintool
from patman import tools
LZ4 = bintool.Bintool.create('lz4')
HAVE_LZ4 = LZ4.is_present()
LZMA_ALONE = bintool.Bintool.create('lzma_alone')
HAVE_LZMA_ALONE = LZMA_ALONE.is_present()
def compress(indata, algo, with_header=True):
"""Compress some data using a given algorithm
Note that for lzma this uses an old version of the algorithm, not that
provided by xz.
This requires 'lz4' and 'lzma_alone' tools. It also requires an output
directory to be previously set up, by calling PrepareOutputDir().
Args:
indata (bytes): Input data to compress
algo (str): Algorithm to use ('none', 'lz4' or 'lzma')
Returns:
bytes: Compressed data
"""
if algo == 'none':
return indata
if algo == 'lz4':
data = LZ4.compress(indata)
# cbfstool uses a very old version of lzma
elif algo == 'lzma':
data = LZMA_ALONE.compress(indata)
else:
raise ValueError("Unknown algorithm '%s'" % algo)
if with_header:
hdr = struct.pack('<I', len(data))
data = hdr + data
return data
def decompress(indata, algo, with_header=True):
"""Decompress some data using a given algorithm
Note that for lzma this uses an old version of the algorithm, not that
provided by xz.
This requires 'lz4' and 'lzma_alone' tools. It also requires an output
directory to be previously set up, by calling PrepareOutputDir().
Args:
indata (bytes): Input data to decompress
algo (str): Algorithm to use ('none', 'lz4' or 'lzma')
Returns:
(bytes) Compressed data
"""
if algo == 'none':
return indata
if with_header:
data_len = struct.unpack('<I', indata[:4])[0]
indata = indata[4:4 + data_len]
if algo == 'lz4':
data = LZ4.decompress(indata)
elif algo == 'lzma':
data = LZMA_ALONE.decompress(indata)
else:
raise ValueError("Unknown algorithm '%s'" % algo)
return data
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