mbred

   1 #!/usr/bin/perl -w
   2 ###APPNAME:     mbred
   3 ###APPAUTHOR:   xiaoranzzz
   4 ###APPDATE:     2009-06-19 01:16:23
   5 ###APPVER:      0.1
   6 ###APPDESC:     Edit MSDOS boot sector record
   7 ###APPUSAGE:    mbred [options] [bootsect_filename]
   8 ###APPEXAMPLE:  mbred -v bootsect.bin
   9 ###APPOPTION:   -v:Display bootsect detail|-d:Hex dump|-o:Set OEM ID|-b|Set bytes per sector|-s:Set sectors count|-S:Set disk size|-l:Set Label
  10 use strict;
  11
  12 #ENV variable MUST be defined somewhere,
  13 #FOR perl to search modules from,
  14 #OR nothing will work
  15 use lib $ENV{XR_PERL_MODULE_DIR};
  16
  17 use MyPlace::Script::Usage qw/help_required help_even_empty/;
  18 exit 0 if(help_required($0,@ARGV));
  19
  20 use Data::Dumper;
  21 my @field = qw/oem bs sc rs fat re s md sf st h hs ls pdn ch sig id vol sys/;
  22 my %mbr = (
  23     $field[0]=>["OEMID","STR",0x03,8,"MSDOS5.0"],
  24     $field[1]=>["Bytes Per Sector","INT",0x0B,2,512],
  25     $field[2]=>["Sectors Per Cluster","INT",0x0D,1,1],
  26     $field[3]=>["Reserved Sectors","INT",0x0E,2,1],
  27     $field[4]=>["FATs","INT",0x10,1,2],
  28     $field[5]=>["Root Entries","INT",0x11,2,224],
  29     $field[6]=>["Small Sectors","INT",0x13,2,2880],
  30     $field[7]=>["Media Descriptor","HEX",0x15,1,"F0"],
  31     $field[8]=>["Sectors Per FAT","INT",0x16,2,9],
  32     $field[9]=>["Sectors Per Track","INT",0x18,2,18],
  33     $field[10]=>["Heads","INT",0x1A,2,2],
  34     $field[11]=>["Hidden Sectors","INT",0x1C,4,0],
  35     $field[12]=>["Large Sectors","INT",0x20,4,0],
  36     $field[13]=>["Physical Drive Number","INT",0x24,1,0],
  37     $field[14]=>["Current Head","INT",0x25,1,0],
  38     $field[15]=>["Signature","INT",0x26,1,41],
  39     $field[16]=>["ID","HEX",0x27,4,"0000"],
  40     $field[17]=>["Volume Label","STR",0x2B,11,"Boot"],
  41     $field[18]=>["System ID","STR",0x36,8,"FAT12"]
  42 );
  43 my $MAXREAD = 512;
  44 my $MINIREAD = 0x36+8;
  45
  46 sub hexdump {
  47     my @result;
  48     my $length = scalar(@_);
  49     push @result,"       0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n";;
  50     for(my $i = 0;$i<$length;$i+=16) {
  51         my $count = $i + 16 >= $length ? $length - 1 : $i + 15;
  52         my @lines = @_[$i..$count];
  53         push @result,sprintf("%03X0  ",$i/16);
  54         push @result,sprintf("%02X "x16,@lines);
  55         push @result,map {/[\p{IsGraph} ]/ ? $_ : "." } map chr,@lines;
  56         push @result,"\n";
  57     }
  58     push @result,"       0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n";;
  59     return @result;
  60 }
  61
  62
  63 sub getvalue {
  64     my $src = shift;
  65     my $fn  = shift;
  66     my $type= $mbr{$fn}->[1];
  67     my $idx = $mbr{$fn}->[2];
  68     my $len = $mbr{$fn}->[3];
  69 #    print STDERR Dumper($mbr{$fn}),"\n";
  70     my @data= @{$src}[$idx..$idx+$len-1];
  71     my $i=0;
  72     my $result="";
  73     if($type eq "HEX") {
  74         for($i..($len-1)) {
  75             $result = sprintf("%02X",$data[$_]) . $result;
  76         }
  77     }
  78     elsif($type eq "STR") {
  79         $result = join("",map chr,@data);
  80     }
  81     else {
  82         $result = 0;
  83         for($i..($len-1)) {
  84             $result = $result + $data[$_]*(256**$_);
  85         }
  86     }
  87     return $result;
  88 }
  89 sub setvalue {
  90     my $dst = shift;
  91     my $fn  = shift;
  92     my $value = shift;
  93     my $type= $mbr{$fn}->[1];
  94     my $idx = $mbr{$fn}->[2];
  95     my $len = $mbr{$fn}->[3];
  96 #    print STDERR Dumper($mbr{$fn}),"\n";
  97     my @data= @{$dst}[$idx..$idx+$len-1];
  98     my $i=0;
  99     my $result;
 100     if($type eq "HEX") {
 101         $value  = hex($value);
 102         $type = "INT";
 103     }
 104     if($type eq "STR") {
 105         @data = map ord,split("",substr($value . " "x$len,0,$len));
 106     }
 107     else {
 108         @data = ();
 109         for($i..($len-1)) {
 110             my $low = $value % 256;
 111             $value = $value / 256;
 112             push @data,$low;
 113         }
 114     }
 115     @{$dst}[$idx..$idx+$len-1]=@data;
 116     return @data;
 117 }
 118
 119
 120 my %opts;
 121 while(@ARGV) {
 122     my $p = shift(@ARGV);
 123     if($p eq '-v' or $p eq '-d') {
 124         $opts{$p}=1;
 125         next;
 126     }
 127     elsif($p =~ /^-/) {
 128         $opts{$p}=shift(@ARGV);
 129     }
 130     else {
 131         $opts{file}=$p;
 132     }
 133 }
 134
 135 my $bytes = "";
 136 if($opts{file}) {
 137     open FI,"<",$opts{file} or die("$!\n");
 138     while(<FI>) {
 139         $bytes .= $_;
 140         last if(length($bytes)>$MAXREAD);
 141     }
 142 }
 143 $bytes = substr($bytes . "\0" x $MINIREAD,0,$MAXREAD);
 144 my @bytes = map ord,split("",$bytes);
 145
 146 foreach(@field) {
 147     my $value = getvalue(\@bytes,$_);
 148     my $type = $mbr{$_}->[1];
 149     my $def = $mbr{$_}->[4];
 150 #    print STDERR ("$_ = $def\n");
 151     next if($value eq $def);
 152     if((!$value) or $value =~ /^[\0x0,\s]+$/) {
 153 #        print STDERR "Assing $_ to default:",$def,"\n";
 154         setvalue(\@bytes,$_,$def);
 155     }
 156     else {
 157         if($type eq "HEX") {
 158             setvalue(\@bytes,$_,$def) if($value =~ /^0+$/);
 159         }
 160     }
 161 }
 162
 163
 164 setvalue(\@bytes,"oem",$opts{-o}) if($opts{-o});
 165 my $secs = getvalue(\@bytes,"s");
 166 my $bs = getvalue(\@bytes,"bs");
 167 if($opts{-S} && $opts{-S} > 0) {
 168     $opts{-S} = $opts{-S} * 1024;
 169     if($opts{-b} && $opts{-b}>0) {
 170         $bs = int($opts{-b});
 171         $secs = int($opts{-S} / $bs);
 172     }
 173     elsif($opts{-s} && $opts{-s}) {
 174         $secs = int($opts{-b});
 175         $bs = int($opts{-S}/$secs);
 176     }
 177     else {
 178         $secs = int($opts{-S}/$bs);
 179     }
 180 }
 181 elsif($opts{-b} && $opts{-b}>0) {
 182     $bs = int($opts{-b});
 183 }
 184 elsif($opts{-s} && $opts{-s}>0) {
 185     $secs = int($opts{-s});
 186 }
 187
 188 setvalue(\@bytes,"bs",$bs);
 189 setvalue(\@bytes,"s",$secs);
 190 my $size = int($secs * $bs / 1024);
 191 my $tracks = 80;
 192 if($size <180) {
 193     setvalue(\@bytes,"h",1);
 194     setvalue(\@bytes,"md","FE");
 195     setvalue(\@bytes,"st",8);
 196     $tracks = 40;
 197 }
 198 elsif($size <320) {
 199     setvalue(\@bytes,"h",1);
 200     setvalue(\@bytes,"md","FC");
 201     setvalue(\@bytes,"st",9);
 202     $tracks = 40;
 203 }
 204 elsif($size <360) {
 205     setvalue(\@bytes,"h",1);
 206     setvalue(\@bytes,"md","FA");
 207     setvalue(\@bytes,"st",8);
 208     $tracks = 80;
 209 }
 210 elsif($size <640) {
 211     setvalue(\@bytes,"h",2);
 212     setvalue(\@bytes,"md","FD");
 213     setvalue(\@bytes,"st",9);
 214     $tracks = 40;
 215 }
 216 elsif($size <720) {
 217     setvalue(\@bytes,"h",2);
 218     setvalue(\@bytes,"md","FB");
 219     setvalue(\@bytes,"st",8);
 220 }
 221 elsif($size <1440) {
 222     setvalue(\@bytes,"h",2);
 223     setvalue(\@bytes,"md","F9");
 224     setvalue(\@bytes,"st",9);
 225 }
 226 elsif($size <2880) {
 227     setvalue(\@bytes,"h",2);
 228     setvalue(\@bytes,"md","F0");
 229     setvalue(\@bytes,"st",18);
 230 }
 231 elsif($size ==2880) {
 232     setvalue(\@bytes,"h",2);
 233     setvalue(\@bytes,"md","F0");
 234     setvalue(\@bytes,"st",36);
 235     setvalue(\@bytes,"sc",2);
 236 }
 237 elsif($size <260000)  {
 238     setvalue(\@bytes,"sc",1);
 239 }
 240 else {
 241     setvalue(\@bytes,"sc",4);
 242 }
 243
 244 if($opts{-v}) {
 245     foreach(@field) {
 246         printf STDERR "%28s : ",$mbr{$_}->[0];
 247         print STDERR getvalue(\@bytes,$_),"\n";
 248     }
 249 }
 250 if($opts{-d}) {
 251     print STDERR hexdump(@bytes),"\n";
 252 }
 253
 254 print map chr,@bytes;# unless($opts{-v} or $opts{-d});
 255
 256