107 lines
4.5 KiB
Python
Executable File
107 lines
4.5 KiB
Python
Executable File
#!/usr/bin/env python
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from __future__ import print_function
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'''
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Helper script to print out the raw content of an ELF section.
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Example usages:
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```
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# print out as bits by default
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extract-section.py .text --input-file=foo.o
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```
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```
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# read from stdin and print out in hex
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cat foo.o | extract-section.py -h .text
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```
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This is merely a wrapper around `llvm-readobj` that focuses on the binary
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content as well as providing more formatting options.
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'''
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# Unfortunately reading binary from stdin is not so trivial in Python...
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def read_raw_stdin():
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import sys
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if sys.version_info >= (3, 0):
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reading_source = sys.stdin.buffer
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else:
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# Windows will always read as string so we need some
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# special handling
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if sys.platform == 'win32':
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import os, msvcrt
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msvcrt.setformat(sys.stdin.fileno(), os.O_BINARY)
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reading_source = sys.stdin
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return reading_source.read()
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def get_raw_section_dump(readobj_path, section_name, input_file):
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import subprocess
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cmd = [readobj_path, '--elf-output-style=GNU', '--hex-dump={}'.format(section_name),
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input_file]
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proc = subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
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if input_file == '-':
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# From stdin
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out,_ = proc.communicate(input=read_raw_stdin())
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else:
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out,_ = proc.communicate()
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return out.decode('utf-8') if type(out) is not str else out
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if __name__ == '__main__':
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import argparse
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# The default '-h' (--help) will conflict with our '-h' (hex) format
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arg_parser = argparse.ArgumentParser(add_help=False)
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arg_parser.add_argument('--readobj-path', metavar='<executable path>', type=str,
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help='Path to llvm-readobj')
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arg_parser.add_argument('--input-file', metavar='<file>', type=str,
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help='Input object file, or \'-\' to read from stdin')
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arg_parser.add_argument('section', metavar='<name>', type=str,
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help='Name of the section to extract')
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# Output format
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format_group = arg_parser.add_mutually_exclusive_group()
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format_group.add_argument('-b', dest='format', action='store_const', const='bits',
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help='Print out in bits')
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arg_parser.add_argument('--byte-indicator', action='store_true',
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help='Whether to print a \'.\' every 8 bits in bits printing mode')
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arg_parser.add_argument('--bits-endian', metavar='<little/big>', type=str,
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choices=['little', 'big'],
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help='Print out bits in specified endianness (little or big); defaults to big')
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format_group.add_argument('-h', dest='format', action='store_const', const='hex',
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help='Print out in hexadecimal')
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arg_parser.add_argument('--hex-width', metavar='<# of bytes>', type=int,
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help='The width (in byte) of every element in hex printing mode')
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arg_parser.add_argument('--help', action='help')
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arg_parser.set_defaults(format='bits', tool_path='llvm-readobj', input_file='-',
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byte_indicator=False, hex_width=4, bits_endian='big')
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args = arg_parser.parse_args()
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raw_section = get_raw_section_dump(args.tool_path, args.section, args.input_file)
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results = []
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for line in raw_section.splitlines(False):
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if line.startswith('Hex dump'):
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continue
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parts = line.strip().split(' ')[1:]
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for part in parts[:4]:
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# exclude any non-hex dump string
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try:
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val = int(part, 16)
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if args.format == 'bits':
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# divided into bytes first
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offsets = (24, 16, 8, 0)
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if args.bits_endian == 'little':
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offsets = (0, 8, 16, 24)
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for byte in [(val >> off) & 0xFF for off in offsets]:
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for bit in [(byte >> off) & 1 for off in range(7, -1, -1)]:
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results.append(str(bit))
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if args.byte_indicator:
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results.append('.')
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elif args.format == 'hex':
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assert args.hex_width <= 4 and args.hex_width > 0
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width_bits = args.hex_width * 8
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offsets = [off for off in range(32 - width_bits, -1, -width_bits)]
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mask = (1 << width_bits) - 1
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format_str = "{:0" + str(args.hex_width * 2) + "x}"
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for word in [(val >> i) & mask for i in offsets]:
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results.append(format_str.format(word))
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except:
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break
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print(' '.join(results), end='')
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