Hridya Valsaraju | d71e39a | 2018-03-21 22:18:19 -0700 | [diff] [blame] | 1 | #!/usr/bin/env python |
| 2 | # Copyright 2018, The Android Open Source Project |
| 3 | # |
| 4 | # Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | # you may not use this file except in compliance with the License. |
| 6 | # You may obtain a copy of the License at |
| 7 | # |
| 8 | # http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | # |
| 10 | # Unless required by applicable law or agreed to in writing, software |
| 11 | # distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | # See the License for the specific language governing permissions and |
| 14 | # limitations under the License. |
| 15 | |
| 16 | """unpacks the bootimage. |
| 17 | |
| 18 | Extracts the kernel, ramdisk, second bootloader and recovery dtbo images. |
| 19 | """ |
| 20 | |
| 21 | from __future__ import print_function |
| 22 | from argparse import ArgumentParser, FileType |
| 23 | from struct import unpack |
| 24 | import os |
| 25 | |
| 26 | |
| 27 | def create_out_dir(dir_path): |
| 28 | """creates a directory 'dir_path' if it does not exist""" |
| 29 | if not os.path.exists(dir_path): |
| 30 | os.makedirs(dir_path) |
| 31 | |
| 32 | |
| 33 | def extract_image(offset, size, bootimage, extracted_image_name): |
| 34 | """extracts an image from the bootimage""" |
| 35 | bootimage.seek(offset) |
| 36 | with open(extracted_image_name, 'wb') as file_out: |
| 37 | file_out.write(bootimage.read(size)) |
| 38 | |
| 39 | |
| 40 | def get_number_of_pages(image_size, page_size): |
| 41 | """calculates the number of pages required for the image""" |
| 42 | return (image_size + page_size - 1) / page_size |
| 43 | |
| 44 | |
| 45 | def unpack_bootimage(args): |
| 46 | """extracts kernel, ramdisk, second bootloader and recovery dtbo""" |
| 47 | boot_magic = unpack('8s', args.boot_img.read(8)) |
| 48 | print('boot_magic: %s' % boot_magic) |
| 49 | kernel_ramdisk_second_info = unpack('10I', args.boot_img.read(10 * 4)) |
| 50 | print('kernel_size: %s' % kernel_ramdisk_second_info[0]) |
| 51 | print('kernel load address: %s' % kernel_ramdisk_second_info[1]) |
| 52 | print('ramdisk size: %s' % kernel_ramdisk_second_info[2]) |
| 53 | print('ramdisk load address: %s' % kernel_ramdisk_second_info[3]) |
| 54 | print('second bootloader size: %s' % kernel_ramdisk_second_info[4]) |
| 55 | print('second bootloader load address: %s' % kernel_ramdisk_second_info[5]) |
| 56 | print('kernel tags load address: %s' % kernel_ramdisk_second_info[6]) |
| 57 | print('page size: %s' % kernel_ramdisk_second_info[7]) |
| 58 | print('boot image header version: %s' % kernel_ramdisk_second_info[8]) |
| 59 | print('os version and patch level: %s' % kernel_ramdisk_second_info[9]) |
| 60 | |
| 61 | product_name = unpack('16s', args.boot_img.read(16)) |
| 62 | print('product name: %s' % product_name) |
| 63 | cmdline = unpack('512s', args.boot_img.read(512)) |
| 64 | print('command line args: %s' % cmdline) |
| 65 | |
| 66 | args.boot_img.read(32) # ignore SHA |
| 67 | |
| 68 | extra_cmdline = unpack('1024s', args.boot_img.read(1024)) |
| 69 | print('additional command line args: %s' % extra_cmdline) |
| 70 | |
| 71 | kernel_size = kernel_ramdisk_second_info[0] |
| 72 | ramdisk_size = kernel_ramdisk_second_info[2] |
| 73 | second_size = kernel_ramdisk_second_info[4] |
| 74 | page_size = kernel_ramdisk_second_info[7] |
| 75 | version = kernel_ramdisk_second_info[8] |
| 76 | if version > 0: |
| 77 | recovery_dtbo_size = unpack('I', args.boot_img.read(1 * 4))[0] |
| 78 | print('recovery dtbo size: %s' % recovery_dtbo_size) |
Hridya Valsaraju | c1cc7ec | 2018-05-31 12:39:58 -0700 | [diff] [blame] | 79 | recovery_dtbo_offset = unpack('Q', args.boot_img.read(8))[0] |
| 80 | print('recovery dtbo offset: %s' % recovery_dtbo_offset) |
Hridya Valsaraju | d71e39a | 2018-03-21 22:18:19 -0700 | [diff] [blame] | 81 | boot_header_size = unpack('I', args.boot_img.read(4))[0] |
| 82 | print('boot header size: %s' % boot_header_size) |
| 83 | else: |
| 84 | recovery_dtbo_size = 0 |
| 85 | |
| 86 | # The first page contains the boot header |
| 87 | num_header_pages = 1 |
| 88 | |
| 89 | num_kernel_pages = get_number_of_pages(kernel_size, page_size) |
| 90 | kernel_offset = page_size * num_header_pages # header occupies a page |
| 91 | image_info_list = [(kernel_offset, kernel_size, 'kernel')] |
| 92 | |
| 93 | num_ramdisk_pages = get_number_of_pages(ramdisk_size, page_size) |
| 94 | ramdisk_offset = page_size * (num_header_pages + num_kernel_pages |
| 95 | ) # header + kernel |
| 96 | image_info_list.append((ramdisk_offset, ramdisk_size, 'ramdisk')) |
| 97 | |
Hridya Valsaraju | d71e39a | 2018-03-21 22:18:19 -0700 | [diff] [blame] | 98 | second_offset = page_size * ( |
| 99 | num_header_pages + num_kernel_pages + num_ramdisk_pages |
| 100 | ) # header + kernel + ramdisk |
| 101 | image_info_list.append((second_offset, second_size, 'second')) |
| 102 | |
| 103 | if recovery_dtbo_size > 0: |
Hridya Valsaraju | c1cc7ec | 2018-05-31 12:39:58 -0700 | [diff] [blame] | 104 | image_info_list.append((recovery_dtbo_offset, recovery_dtbo_size, |
Hridya Valsaraju | d71e39a | 2018-03-21 22:18:19 -0700 | [diff] [blame] | 105 | 'recovery_dtbo')) |
| 106 | |
| 107 | for image_info in image_info_list: |
| 108 | extract_image(image_info[0], image_info[1], args.boot_img, |
| 109 | os.path.join(args.out, image_info[2])) |
| 110 | |
| 111 | |
| 112 | def parse_cmdline(): |
| 113 | """parse command line arguments""" |
| 114 | parser = ArgumentParser( |
| 115 | description='Unpacks boot.img/recovery.img, extracts the kernel,' |
| 116 | 'ramdisk, second bootloader and recovery dtbo') |
| 117 | parser.add_argument( |
| 118 | '--boot_img', |
| 119 | help='path to boot image', |
| 120 | type=FileType('rb'), |
| 121 | required=True) |
| 122 | parser.add_argument('--out', help='path to out binaries', default='out') |
| 123 | return parser.parse_args() |
| 124 | |
| 125 | |
| 126 | def main(): |
| 127 | """parse arguments and unpack boot image""" |
| 128 | args = parse_cmdline() |
| 129 | create_out_dir(args.out) |
| 130 | unpack_bootimage(args) |
| 131 | |
| 132 | |
| 133 | if __name__ == '__main__': |
| 134 | main() |