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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 patman import tools
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().
Care is taken to use unique temporary files so that this function can be
called from multiple threads.
Args:
indata (bytes): Input data to compress
algo (str): Algorithm to use ('none', 'gzip', 'lz4' or 'lzma')
Returns:
bytes: Compressed data
"""
if algo == 'none':
return indata
fname = tempfile.NamedTemporaryFile(prefix='%s.comp.tmp' % algo,
dir=tools.GetOutputDir()).name
tools.WriteFile(fname, indata)
if algo == 'lz4':
data = tools.Run('lz4', '--no-frame-crc', '-B4', '-5', '-c', fname,
binary=True)
# cbfstool uses a very old version of lzma
elif algo == 'lzma':
outfname = tempfile.NamedTemporaryFile(prefix='%s.comp.otmp' % algo,
dir=tools.GetOutputDir()).name
tools.Run('lzma_alone', 'e', fname, outfname, '-lc1', '-lp0', '-pb0',
'-d8')
data = tools.ReadFile(outfname)
elif algo == 'gzip':
data = tools.Run('gzip', '-c', fname, binary=True)
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', 'gzip', '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]
fname = tools.GetOutputFilename('%s.decomp.tmp' % algo)
tools.WriteFile(fname, indata)
if algo == 'lz4':
data = tools.Run('lz4', '-dc', fname, binary=True)
elif algo == 'lzma':
outfname = tools.GetOutputFilename('%s.decomp.otmp' % algo)
tools.Run('lzma_alone', 'd', fname, outfname)
data = tools.ReadFile(outfname, binary=True)
elif algo == 'gzip':
data = tools.Run('gzip', '-cd', fname, binary=True)
else:
raise ValueError("Unknown algorithm '%s'" % algo)
return data
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