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;

if ( !seek(FILE,64,0) ) {
    die "$0: 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;
}

if ( !seek(FILE,16,0) ) {
    die "$0: 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	if ( !seek(FILE,64,0) ) {
16	die "$0: Cannot seek past header\n";
17	}
18
19	$csum = 0;
20	$bytes = 64;
21	while ( ($n = read(FILE, $dw, 4)) > 0 ) {
22	$dw .= "\0\0\0\0"; # Pad to at least 32 bits
23	($v) = unpack("V", $dw);
24	$csum = ($csum + $v) & 0xffffffff;
25	$bytes += $n;
26	}
27
28	if ( !seek(FILE,16,0) ) {
29	die "$0: Cannot seek to header\n";
30	}
31
32	print FILE pack("VV", $bytes, $csum);
33
34	close(FILE);
35
36	exit 0;