scripts/signrom.py

   1 #
   2 # Option ROM signing utility
   3 #
   4 # Authors:
   5 #  Jan Kiszka <jan.kiszka@siemens.com>
   6 #
   7 # This work is licensed under the terms of the GNU GPL, version 2 or later.
   8 # See the COPYING file in the top-level directory.
   9
  10 import sys
  11 import struct
  12
  13 if len(sys.argv) < 3:
  14     print('usage: signrom.py input output')
  15     sys.exit(1)
  16
  17 fin = open(sys.argv[1], 'rb')
  18 fout = open(sys.argv[2], 'wb')
  19
  20 fin.seek(2)
  21 size = ord(fin.read(1)) * 512 - 1
  22
  23 fin.seek(0)
  24 data = fin.read(size)
  25 fout.write(data)
  26
  27 checksum = 0
  28 for b in data:
  29     # catch Python 2 vs. 3 differences
  30     if isinstance(b, int):
  31         checksum += b
  32     else:
  33         checksum += ord(b)
  34 checksum = (256 - checksum) % 256
  35
  36 # Python 3 no longer allows chr(checksum)
  37 fout.write(struct.pack('B', checksum))
  38
  39 fin.close()
  40 fout.close()