scsi: esp: check buffer length before reading scsi command
[qemu.git] / 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 magic = fin.read(2)
21 if magic != '\x55\xaa':
22 sys.exit("%s: option ROM does not begin with magic 55 aa" % sys.argv[1])
23
24 size_byte = ord(fin.read(1))
25 fin.seek(0)
26
27 if size_byte == 0:
28 # If the caller left the size field blank then we will fill it in,
29 # also rounding the whole input to a multiple of 512 bytes.
30 data = fin.read()
31 # +1 because we need a byte to store the checksum.
32 size = len(data) + 1
33 # Round up to next multiple of 512.
34 size += 511
35 size -= size % 512
36 if size >= 65536:
37 sys.exit("%s: option ROM size too large" % sys.argv[1])
38 # size-1 because a final byte is added below to store the checksum.
39 data = data.ljust(size-1, '\0')
40 data = data[:2] + chr(size/512) + data[3:]
41 else:
42 # Otherwise the input file specifies the size so use it.
43 # -1 because we overwrite the last byte of the file with the checksum.
44 size = size_byte * 512 - 1
45 data = fin.read(size)
46
47 fout.write(data)
48
49 checksum = 0
50 for b in data:
51 # catch Python 2 vs. 3 differences
52 if isinstance(b, int):
53 checksum += b
54 else:
55 checksum += ord(b)
56 checksum = (256 - checksum) % 256
57
58 # Python 3 no longer allows chr(checksum)
59 fout.write(struct.pack('B', checksum))
60
61 fin.close()
62 fout.close()