Jooyung Han | d35952e | 2021-11-08 17:53:47 +0900 | [diff] [blame] | 1 | #!/usr/bin/env python |
| 2 | # |
| 3 | # Copyright (C) 2021 The Android Open Source Project |
| 4 | # |
| 5 | # Licensed under the Apache License, Version 2.0 (the "License"); |
| 6 | # you may not use this file except in compliance with the License. |
| 7 | # You may obtain a copy of the License at |
| 8 | # |
| 9 | # http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | # |
| 11 | # Unless required by applicable law or agreed to in writing, software |
| 12 | # distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | # See the License for the specific language governing permissions and |
| 15 | # limitations under the License. |
| 16 | """replace_bytes is a command line tool to replace bytes in a file. |
| 17 | |
| 18 | Typical usage: replace_bytes target_file old_file new_file |
| 19 | |
| 20 | replace bytes of old_file with bytes of new_file in target_file. old_file and new_file should be |
| 21 | the same size. |
| 22 | |
| 23 | """ |
| 24 | import argparse |
| 25 | import sys |
| 26 | |
| 27 | |
| 28 | def ParseArgs(argv): |
| 29 | parser = argparse.ArgumentParser(description='Replace bytes') |
| 30 | parser.add_argument( |
| 31 | 'target_file', |
| 32 | help='path to the target file.') |
| 33 | parser.add_argument( |
| 34 | 'old_file', |
| 35 | help='path to the file containing old bytes') |
| 36 | parser.add_argument( |
| 37 | 'new_file', |
| 38 | help='path to the file containing new bytes') |
| 39 | return parser.parse_args(argv) |
| 40 | |
| 41 | |
| 42 | def ReplaceBytes(target_file, old_file, new_file): |
| 43 | # read old bytes |
| 44 | with open(old_file, 'rb') as f: |
| 45 | old_bytes = f.read() |
| 46 | |
| 47 | # read new bytes |
| 48 | with open(new_file, 'rb') as f: |
| 49 | new_bytes = f.read() |
| 50 | |
| 51 | assert len(old_bytes) == len(new_bytes), 'Pubkeys should be the same size. (%d != %d)' % ( |
| 52 | len(old_bytes), len(new_bytes)) |
| 53 | |
| 54 | # replace bytes in target_file |
| 55 | with open(target_file, 'r+b') as f: |
| 56 | pos = f.read().find(old_bytes) |
| 57 | assert pos != -1, 'Pubkey not found' |
| 58 | f.seek(pos) |
| 59 | f.write(new_bytes) |
| 60 | |
| 61 | |
| 62 | def main(argv): |
| 63 | try: |
| 64 | args = ParseArgs(argv) |
| 65 | ReplaceBytes(args.target_file, args.old_file, args.new_file) |
| 66 | except Exception as e: |
| 67 | print(e) |
| 68 | sys.exit(1) |
| 69 | |
| 70 | |
| 71 | if __name__ == '__main__': |
| 72 | main(sys.argv[1:]) |