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- #
- # Option ROM signing utility
- #
- # Authors:
- # Jan Kiszka <jan.kiszka@siemens.com>
- #
- # This work is licensed under the terms of the GNU GPL, version 2 or later.
- # See the COPYING file in the top-level directory.
- import sys
- import struct
- if len(sys.argv) < 3:
- print('usage: signrom.py input output')
- sys.exit(1)
- fin = open(sys.argv[1], 'rb')
- fout = open(sys.argv[2], 'wb')
- fin.seek(2)
- size_byte = ord(fin.read(1))
- fin.seek(0)
- if size_byte == 0:
- # If the caller left the size field blank then we will fill it in,
- # also rounding the whole input to a multiple of 512 bytes.
- data = fin.read()
- # +1 because we need a byte to store the checksum.
- size = len(data) + 1
- # Round up to next multiple of 512.
- size += 511
- size -= size % 512
- if size >= 65536:
- sys.exit("%s: option ROM size too large" % sys.argv[1])
- # size-1 because a final byte is added below to store the checksum.
- data = data.ljust(size-1, '\0')
- data = data[:2] + chr(size/512) + data[3:]
- else:
- # Otherwise the input file specifies the size so use it.
- # -1 because we overwrite the last byte of the file with the checksum.
- size = size_byte * 512 - 1
- data = fin.read(size)
- fout.write(data)
- checksum = 0
- for b in data:
- # catch Python 2 vs. 3 differences
- if isinstance(b, int):
- checksum += b
- else:
- checksum += ord(b)
- checksum = (256 - checksum) % 256
- # Python 3 no longer allows chr(checksum)
- fout.write(struct.pack('B', checksum))
- fin.close()
- fout.close()
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