mkinitrd-magellan/isolinux/checksumiso.pl

#!/usr/bin/perl
#
# Construct a checksum for isolinux*.bin, compatible
# with an mkisofs boot-info-table
#

use bytes;
use integer;

($file) = @ARGV;

open(FILE, '+<', $file) or die "$0: cannot open $file: $!\n";
binmode FILE;

@fstat = stat(FILE) or die "$0: stat $file: $!\n";
if (!$fstat[7]) {
    die "$0: $file: cannot query length\n";
}

# Pad file to a multiple of 2048 bytes
$frac = $fstat[7] % 2048;
if ($frac) {
    seek(FILE,$fstat[7],0)
	or die "$0: $file: cannot seek to end\n";
    print FILE "\0" x (2048-$frac);
}

# Checksum the file post header
if ( !seek(FILE,64,0) ) {
    die "$0: $file: cannot seek past header\n";
}

$csum  = 0;
$bytes = 64;
while ( ($n = read(FILE, $dw, 4)) > 0 ) {
    $dw .= "\0\0\0\0";		# Pad to at least 32 bits
    ($v) = unpack("V", $dw);
    $csum  = ($csum + $v) & 0xffffffff;
    $bytes += $n;
}

# Update header
if ( !seek(FILE,16,0) ) {
    die "$0: $file: cannot seek to header\n";
}

print FILE pack("VV", $bytes, $csum);

close(FILE);

exit 0;
1	#!/usr/bin/perl
2	#
3	# Construct a checksum for isolinux*.bin, compatible
4	# with an mkisofs boot-info-table
5	#
6
7	use bytes;
8	use integer;
9
10	($file) = @ARGV;
11
12	open(FILE, '+<', $file) or die "$0: cannot open $file: $!\n";
13	binmode FILE;
14
15	@fstat = stat(FILE) or die "$0: stat $file: $!\n";
16	if (!$fstat[7]) {
17	die "$0: $file: cannot query length\n";
18	}
19
20	# Pad file to a multiple of 2048 bytes
21	$frac = $fstat[7] % 2048;
22	if ($frac) {
23	seek(FILE,$fstat[7],0)
24	or die "$0: $file: cannot seek to end\n";
25	print FILE "\0" x (2048-$frac);
26	}
27
28	# Checksum the file post header
29	if ( !seek(FILE,64,0) ) {
30	die "$0: $file: cannot seek past header\n";
31	}
32
33	$csum = 0;
34	$bytes = 64;
35	while ( ($n = read(FILE, $dw, 4)) > 0 ) {
36	$dw .= "\0\0\0\0"; # Pad to at least 32 bits
37	($v) = unpack("V", $dw);
38	$csum = ($csum + $v) & 0xffffffff;
39	$bytes += $n;
40	}
41
42	# Update header
43	if ( !seek(FILE,16,0) ) {
44	die "$0: $file: cannot seek to header\n";
45	}
46
47	print FILE pack("VV", $bytes, $csum);
48
49	close(FILE);
50
51	exit 0;