disk-mgmt/phantomlabel

   1 #!/usr/bin/env perl
   2
   3 use warnings;
   4 $myname = "phantomlabel";
   5 $offset_signature = 0x10040;
   6 $size_signature = 8;
   7 $signature = '_BHRfS_M';
   8 $offset_label = 0x1012B;
   9 $size_buf_label = 100;
  10
  11 $new_label = $ARGV[1];
  12 if(defined $new_label)
  13 {
  14         if(length $new_label > $size_buf_label - 1)
  15         {
  16                 die "$myname: label must not exceed $size_buf_label bytes\n";
  17         }
  18         if($new_label =~ m{[/\\]})
  19         {
  20                 die "$myname: label must not contain '/' or '\\' char\n";
  21         }
  22 }
  23
  24 open $target_device, '+<', $ARGV[0] or die "$myname: open: $!";
  25
  26 sub show_current_data
  27 {
  28         seek $target_device, $offset_signature, 0 or die "$myname: seek: $!";
  29         $read_bytes = read $target_device, $buf_signature, $size_signature or die "$myname: read: $!";
  30         if($read_bytes != $size_signature)
  31         {
  32                 die sprintf "%s: could not read %d bytes at 0x%X\n", $myname, $size_signature, $offset_signature;
  33         }
  34         printf "# octets at 0x%X\n", $offset_signature;
  35         printf "%s\n", join " ", map { sprintf "%02X", $_ } unpack 'C'.$size_signature, $buf_signature;
  36
  37         $size_buf_new_label = defined $new_label ? length($new_label) + 1 : 100;
  38         seek $target_device, $offset_label, 0 or die "$myname: seek: $!";
  39         $read_bytes = read $target_device, $buf_label, $size_buf_new_label or die "$myname: read: $!";
  40         if($read_bytes != $size_buf_new_label)
  41         {
  42                 die sprintf "%s: could not read %d bytes at 0x%X\n", $myname, $size_buf_new_label, $offset_label;
  43         }
  44         printf "# octets at 0x%X\n", $offset_label;
  45         printf "%s\n", join " ", map { sprintf "%02X", $_ } unpack 'C'.$size_buf_new_label, $buf_label;
  46 }
  47
  48 show_current_data;
  49
  50 if(defined $new_label)
  51 {
  52         print "# writing new label\n";
  53
  54         seek $target_device, $offset_signature, 0 or die "$myname: seek: $!";
  55         print {$target_device} $signature or die "$myname: write: $!";
  56
  57         seek $target_device, $offset_label, 0 or die "$myname: seek: $!";
  58         print {$target_device} $new_label.chr(0) or die "$myname: write: $!";
  59
  60         print "# new label is written\n";
  61
  62         show_current_data;
  63 }