| #!/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; |
