261 lines
8.1 KiB
Python
Executable File
261 lines
8.1 KiB
Python
Executable File
#!/usr/bin/env python
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#
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# Copyright (C) 2018 The Android Open Source Project
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""
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A tool to extract kernel information from a kernel image.
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"""
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import argparse
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import subprocess
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import sys
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import re
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CONFIG_PREFIX = b'IKCFG_ST'
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GZIP_HEADER = b'\037\213\010'
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COMPRESSION_ALGO = (
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(["gzip", "-d"], GZIP_HEADER),
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(["xz", "-d"], b'\3757zXZ\000'),
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(["bzip2", "-d"], b'BZh'),
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(["lz4", "-d", "-l"], b'\002\041\114\030'),
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# These are not supported in the build system yet.
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# (["unlzma"], b'\135\0\0\0'),
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# (["lzop", "-d"], b'\211\114\132'),
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)
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# "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
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# LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n";
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LINUX_BANNER_PREFIX = b'Linux version '
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LINUX_BANNER_REGEX = LINUX_BANNER_PREFIX + \
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r'(?P<release>(?P<version>[0-9]+[.][0-9]+[.][0-9]+).*) \(.*@.*\) \((?P<compiler>.*)\) .*\n'
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def get_from_release(input_bytes, start_idx, key):
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null_idx = input_bytes.find('\x00', start_idx)
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if null_idx < 0:
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return None
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try:
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linux_banner = input_bytes[start_idx:null_idx].decode()
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except UnicodeDecodeError:
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return None
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mo = re.match(LINUX_BANNER_REGEX, linux_banner)
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if mo:
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return mo.group(key)
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return None
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def dump_from_release(input_bytes, key):
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"""
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Helper of dump_version and dump_release
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"""
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idx = 0
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while True:
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idx = input_bytes.find(LINUX_BANNER_PREFIX, idx)
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if idx < 0:
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return None
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value = get_from_release(input_bytes, idx, key)
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if value:
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return value
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idx += len(LINUX_BANNER_PREFIX)
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def dump_version(input_bytes):
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"""
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Dump kernel version, w.x.y, from input_bytes. Search for the string
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"Linux version " and do pattern matching after it. See LINUX_BANNER_REGEX.
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"""
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return dump_from_release(input_bytes, "version")
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def dump_compiler(input_bytes):
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"""
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Dump kernel version, w.x.y, from input_bytes. Search for the string
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"Linux version " and do pattern matching after it. See LINUX_BANNER_REGEX.
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"""
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return dump_from_release(input_bytes, "compiler")
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def dump_release(input_bytes):
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"""
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Dump kernel release, w.x.y-..., from input_bytes. Search for the string
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"Linux version " and do pattern matching after it. See LINUX_BANNER_REGEX.
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"""
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return dump_from_release(input_bytes, "release")
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def dump_configs(input_bytes):
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"""
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Dump kernel configuration from input_bytes. This can be done when
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CONFIG_IKCONFIG is enabled, which is a requirement on Treble devices.
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The kernel configuration is archived in GZip format right after the magic
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string 'IKCFG_ST' in the built kernel.
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"""
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# Search for magic string + GZip header
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idx = input_bytes.find(CONFIG_PREFIX + GZIP_HEADER)
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if idx < 0:
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return None
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# Seek to the start of the archive
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idx += len(CONFIG_PREFIX)
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sp = subprocess.Popen(["gzip", "-d", "-c"], stdin=subprocess.PIPE,
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stdout=subprocess.PIPE, stderr=subprocess.PIPE)
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o, _ = sp.communicate(input=input_bytes[idx:])
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if sp.returncode == 1: # error
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return None
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# success or trailing garbage warning
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assert sp.returncode in (0, 2), sp.returncode
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return o
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def try_decompress_bytes(cmd, input_bytes):
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sp = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
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stderr=subprocess.PIPE)
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o, _ = sp.communicate(input=input_bytes)
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# ignore errors
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return o
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def try_decompress(cmd, search_bytes, input_bytes):
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idx = 0
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while True:
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idx = input_bytes.find(search_bytes, idx)
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if idx < 0:
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raise StopIteration()
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yield try_decompress_bytes(cmd, input_bytes[idx:])
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idx += 1
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def decompress_dump(func, input_bytes):
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"""
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Run func(input_bytes) first; and if that fails (returns value evaluates to
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False), then try different decompression algorithm before running func.
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"""
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o = func(input_bytes)
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if o:
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return o
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for cmd, search_bytes in COMPRESSION_ALGO:
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for decompressed in try_decompress(cmd, search_bytes, input_bytes):
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if decompressed:
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o = decompress_dump(func, decompressed)
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if o:
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return o
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# Force decompress the whole file even if header doesn't match
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decompressed = try_decompress_bytes(cmd, input_bytes)
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if decompressed:
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o = decompress_dump(func, decompressed)
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if o:
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return o
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def dump_to_file(f, dump_fn, input_bytes, desc):
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"""
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Call decompress_dump(dump_fn, input_bytes) and write to f. If it fails, return
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False; otherwise return True.
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"""
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if f is not None:
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o = decompress_dump(dump_fn, input_bytes)
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if o:
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f.write(o)
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else:
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sys.stderr.write(
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"Cannot extract kernel {}".format(desc))
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return False
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return True
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def main():
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parser = argparse.ArgumentParser(
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formatter_class=argparse.RawTextHelpFormatter,
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description=__doc__ +
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"\nThese algorithms are tried when decompressing the image:\n " +
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" ".join(tup[0][0] for tup in COMPRESSION_ALGO))
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parser.add_argument('--input',
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help='Input kernel image. If not specified, use stdin',
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metavar='FILE',
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type=argparse.FileType('rb'),
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default=sys.stdin)
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parser.add_argument('--output-configs',
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help='If specified, write configs. Use stdout if no file '
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'is specified.',
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metavar='FILE',
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nargs='?',
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type=argparse.FileType('wb'),
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const=sys.stdout)
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parser.add_argument('--output-version',
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help='If specified, write version. Use stdout if no file '
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'is specified.',
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metavar='FILE',
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nargs='?',
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type=argparse.FileType('wb'),
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const=sys.stdout)
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parser.add_argument('--output-release',
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help='If specified, write kernel release. Use stdout if '
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'no file is specified.',
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metavar='FILE',
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nargs='?',
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type=argparse.FileType('wb'),
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const=sys.stdout)
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parser.add_argument('--output-compiler',
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help='If specified, write the compiler information. Use stdout if no file '
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'is specified.',
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metavar='FILE',
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nargs='?',
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type=argparse.FileType('wb'),
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const=sys.stdout)
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parser.add_argument('--tools',
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help='Decompression tools to use. If not specified, PATH '
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'is searched.',
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metavar='ALGORITHM:EXECUTABLE',
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nargs='*')
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args = parser.parse_args()
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tools = {pair[0]: pair[1]
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for pair in (token.split(':') for token in args.tools or [])}
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for cmd, _ in COMPRESSION_ALGO:
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if cmd[0] in tools:
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cmd[0] = tools[cmd[0]]
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input_bytes = args.input.read()
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ret = 0
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if not dump_to_file(args.output_configs, dump_configs, input_bytes,
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"configs in {}".format(args.input.name)):
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ret = 1
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if not dump_to_file(args.output_version, dump_version, input_bytes,
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"version in {}".format(args.input.name)):
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ret = 1
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if not dump_to_file(args.output_release, dump_release, input_bytes,
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"kernel release in {}".format(args.input.name)):
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ret = 1
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if not dump_to_file(args.output_compiler, dump_compiler, input_bytes,
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"kernel compiler in {}".format(args.input.name)):
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ret = 1
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return ret
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if __name__ == '__main__':
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sys.exit(main())
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