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import argparse
import pychrysalide
from pychrysalide.analysis.contents import FileContent
from pychrysalide.format.bootimg import BootImgFormat
import struct
def _value_to_string(val):
"""Convert a field into a string."""
encodings = [ 'ascii', 'utf-8', 'utf-16' ]
desc = None
for enc in encodings:
try:
desc = '"%s"' % val.decode(enc)
except:
desc = None
if desc:
break
if not(desc):
count = val.find(b'\x00')
if count == -1:
count = len(val)
desc = '%u byte(s)' % count
return desc
def _value_to_size(val):
"""Convert a field into a human-readable size."""
unit = 0
units = [ '', 'Kb', 'Mb', 'Gb' ]
for i in range(3):
if val > 1024:
val /= 1024
unit += 1
if val == int(val):
return '%u%s' % (val, units[unit])
else:
return '%.1f%s' % (val, units[unit])
def _value_to_id(val):
"""Convert a field into an identifier."""
values = struct.unpack('<IIIIIIII', val)
return ' '.join(['0x%08x' % v for v in values])
def show_info(fmt):
"""Display all available information about a given Boot image."""
hdr = fmt.header
items = [
[ 'magic', _value_to_string(hdr.magic) ],
[ 'kernel_size', _value_to_size(hdr.kernel_size) ],
[ 'kernel_addr', hex(hdr.kernel_addr) ],
[ 'ramdisk_size', _value_to_size(hdr.ramdisk_size) ],
[ 'ramdisk_addr', hex(hdr.ramdisk_addr) ],
[ 'second_size', _value_to_size(hdr.second_size) ],
[ 'second_addr', hex(hdr.second_addr) ],
[ 'tags_addr', hex(hdr.tags_addr) ],
[ 'page_size', _value_to_size(hdr.page_size) ],
[ 'header_version', hdr.header_version ],
[ 'os_version', hex(hdr.os_version) ],
[ 'name', _value_to_string(hdr.name) ],
[ 'cmdline', _value_to_string(hdr.cmdline) ],
[ 'id', _value_to_id(hdr.id) ],
[ 'extra_cmdline', _value_to_string(hdr.extra_cmdline) ],
[ 'recovery_dtbo_size', _value_to_size(hdr.recovery_dtbo_size) ],
[ 'recovery_dtbo_offset', hex(hdr.recovery_dtbo_offset) ],
[ 'header_size', _value_to_size(hdr.header_size) ],
]
length = 0
for key, _ in items:
if (len(key) + 1) > length:
length = len(key) + 1
line = ' {:<%u} {:}' % length
title = ' Boot image header'
print()
print(title)
print('=' * len(title))
for key, val in items:
print(line.format(key + ':', val))
print()
if __name__ == '__main__':
"""Script entry point."""
parser = argparse.ArgumentParser()
parser.add_argument('-i', '--info', help='display information about the boot image', action='store_true')
parser.add_argument('-k', '--kernel', help='dump the kernel embedded in the boot image', action='store_true')
parser.add_argument('-r', '--ramdisk', help='dump the ramdisk embedded in the boot image', action='store_true')
parser.add_argument('filename', help='path to the Android boot image', metavar='boot.img')
args = parser.parse_args()
cnt = FileContent(args.filename)
if cnt is None:
sys.exit('No content to load!')
fmt = BootImgFormat(cnt)
status = fmt.analyze()
if not(status):
sys.exit('Bad boot image!')
if args.info:
show_info(fmt)
if args.kernel:
if fmt.kernel:
with open('kernel.bin', 'wb') as fd:
fd.write(fmt.kernel.data)
else:
print('No kernel to extract!')
if args.ramdisk:
if fmt.ramdisk:
with open('ramdisk.bin', 'wb') as fd:
fd.write(fmt.ramdisk.data)
else:
print('No ramdisk to extract!')
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