mkdiskimage

   1 #!/usr/bin/perl
   2 ## -----------------------------------------------------------------------
   3 ##
   4 ##   Copyright 2002-2007 H. Peter Anvin - All Rights Reserved
   5 ##
   6 ##   This program is free software; you can redistribute it and/or modify
   7 ##   it under the terms of the GNU General Public License as published by
   8 ##   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   9 ##   Boston MA 02111-1307, USA; either version 2 of the License, or
  10 ##   (at your option) any later version; incorporated herein by reference.
  11 ##
  12 ## -----------------------------------------------------------------------
  13
  14 #
  15 # Creates a blank MS-DOS formatted hard disk image
  16 #
  17
  18 use bytes;
  19 use integer;
  20 use Fcntl;
  21 use Errno;
  22 use Cwd;
  23 use IO::Handle;                 # For flush()
  24
  25 sub absolute_path($) {
  26     my($f) = @_;
  27     my($c);
  28
  29     return $f if ( $f =~ /^\// );
  30     $c = cwd();
  31     $c = '' if ( $c eq '/' );
  32     return $c.'/'.$f;
  33 }
  34
  35 sub is_linux() {
  36     return !!eval '{ '.
  37         'use POSIX; '.
  38         '($sysname, $nodename, $release, $version, $machine) = POSIX::uname(); '.
  39         "return \$sysname eq \'Linux\'; }";
  40 }
  41
  42 sub get_random() {
  43     # Get a 32-bit random number
  44     my $rfd, $rnd;
  45     my $rid;
  46
  47     if (sysopen($rfd, '/dev/urandom', O_RDONLY) &&
  48         sysread($rfd, $rnd, 4) == 4) {
  49         $rid = unpack("V", $rnd);
  50     }
  51
  52     close($rfd) if (defined($rfd));
  53     return $rid if (defined($rid));
  54
  55     # This sucks but is better than nothing...
  56     return ($$+time()) & 0xffffffff;
  57 }
  58
  59 $is_linux = is_linux();
  60 if ( $is_linux ) {
  61     # IOCTL numbers
  62     $BLKRRPART    = 0x125f;
  63     $BLKGETSIZE   = 0x1260;
  64 }
  65
  66 %opt = ();
  67 @args = ();
  68
  69 while (defined($a = shift(@ARGV))) {
  70     if ( $a =~ /^\-/ ) {
  71         foreach $o ( split(//, substr($a,1)) ) {
  72             $opt{$o} = 1;
  73             if ($o eq 'i') {
  74                 $id = shift(@ARGV);
  75             }
  76         }
  77     } else {
  78         push(@args, $a);
  79     }
  80 }
  81
  82 ($file,$c,$h,$s) = @args;
  83 $c += 0;  $h += 0;  $s += 0;
  84
  85 $pentry = 1;
  86 $pentry = 2 if ( $opt{'2'} );
  87 $pentry = 3 if ( $opt{'3'} );
  88 $pentry = 4 if ( $opt{'4'} );
  89
  90 if ( $opt{'z'} ) {
  91     $h = $h || 64;
  92     $s = $s || 32;
  93 }
  94
  95 if ( $opt{'M'} && $h && $s ) {
  96     # Specify size in megabytes, not in cylinders
  97     $c = ($c*1024*2)/($h*$s);
  98 }
  99
 100 $is_open = 0;
 101
 102 if ( $c == 0 && $file ne '' ) {
 103     $len = 0;
 104     if ( sysopen(OUTPUT, $file, O_RDWR, 0666) ) {
 105         $is_open = 1;
 106
 107         if ( (@filestat = stat(OUTPUT)) && S_ISREG($filestat[2]) ) {
 108             $len = $filestat[7] >> 9;
 109         } elsif ( $is_linux && S_ISBLK($filestat[2]) ) {
 110             $blksize = pack("L!", 0);
 111             if ( ioctl(OUTPUT, $BLKGETSIZE, $blksize) == 0 ) {
 112                 $len = unpack("L!", $blksize); # In 512-byte sectors!
 113             }
 114         }
 115     }
 116
 117     if ( !$len ) {
 118         print STDERR "$0: $file: don't know how to determine the size of this device\n";
 119         exit 1;
 120     }
 121
 122     $c = $len/($h*$s);
 123 }
 124
 125 if ( $file eq '' || $c < 1 || $h < 1 || $h > 256 || $s < 1 || $s > 63 ) {
 126     print STDERR "Usage: $0 [-doFMz4][-i id] file c h s (max: 1024 256 63)\n";
 127     print STDERR "    -d    add DOSEMU header\n";
 128     print STDERR "    -o    print filesystem offset to stdout\n";
 129     print STDERR "    -F    format partition as FAT32\n";
 130     print STDERR "    -M    \"c\" argument is megabytes, calculate cylinders\n";
 131     print STDERR "    -z    use zipdisk geometry (h=64 s=32)\n";
 132     print STDERR "    -4    use partition entry 4 (standard for zipdisks)\n";
 133     print STDERR "    -i    specify the MBR ID\n";
 134     exit 1;
 135 }
 136
 137 if ($c > 1024) {
 138     print STDERR "Warning: more than 1024 cylinders ($c).\n";
 139     print STDERR "Not all BIOSes will be able to boot this device.\n";
 140     $cc = 1024;
 141 } else {
 142     $cc = $c;
 143 }
 144
 145 $cylsize = $h*$s*512;
 146
 147 if ( !$is_open ) {
 148     sysopen(OUTPUT, $file, O_CREAT|O_RDWR|O_TRUNC, 0666)
 149         or die "$0: Cannot open: $file\n";
 150 }
 151 binmode OUTPUT;
 152
 153 # Print out DOSEMU header, if requested
 154 if ( $opt{'d'} ) {
 155     $emuhdr = "DOSEMU\0" . pack("VVVV", $h, $s, $c, 128);
 156     $emuhdr .= "\0" x (128 - length($emuhdr));
 157     print OUTPUT $emuhdr;
 158 }
 159
 160 # Print the MBR and partition table
 161 $mbr = '';
 162 while ( $line = <DATA> ) {
 163     chomp $line;
 164     foreach $byte ( split(/\s+/, $line) ) {
 165         $mbr .= chr(hex($byte));
 166     }
 167 }
 168 if ( length($mbr) > 440 ) {
 169     die "$0: Bad MBR code\n";
 170 }
 171
 172 $mbr .= "\0" x (440 - length($mbr));
 173 if (defined($id)) {
 174     $id = to_int($id);
 175 } else {
 176     $id = get_random();
 177 }
 178 $mbr .= pack("V", $id);         # Offset 440: MBR ID
 179 $mbr .= "\0\0";                 # Offset 446: actual partition table
 180
 181 print OUTPUT $mbr;
 182
 183 # Print partition table
 184 $psize = $c*$h*$s-$s;
 185 $bhead   = ($h > 1) ? 1 : 0;
 186 $bsect   = 1;
 187 $bcyl    = ($h > 1) ? 0 : 1;
 188 $ehead   = $h-1;
 189 $esect   = $s + ((($cc-1) & 0x300) >> 2);
 190 $ecyl    = ($cc-1) & 0xff;
 191 if ( $c > 1024 ) {
 192     $fstype = 0x0e;
 193 } elsif ( $psize > 65536 ) {
 194     $fstype = 0x06;
 195 } else {
 196     $fstype = 0x04;
 197 }
 198 for ( $i = 1 ; $i <= 4 ; $i++ ) {
 199     if ( $i == $pentry ) {
 200         print OUTPUT pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype,
 201                           $ehead, $esect, $ecyl, $s, $psize);
 202     } else {
 203         print OUTPUT "\0" x 16;
 204     }
 205 }
 206 print OUTPUT "\x55\xaa";
 207
 208 # Output blank file
 209 $totalsize = $c*$h*$s;
 210 $tracks    = $c*$h;
 211
 212 $track = "\0" x (512*$s);
 213
 214 # Print fractional track
 215 print OUTPUT "\0" x (512 * ($s-1));
 216
 217 for ( $i = 1 ; $i < $tracks ; $i++ ) {
 218     print OUTPUT $track;
 219 }
 220
 221 # Print mtools temp file
 222 $n = 0;
 223 while ( !defined($tmpdir) ) {
 224     $tmpdir = "/tmp/mkdiskimage.$$.".($n++);
 225     if ( !mkdir($tmpdir, 0700) ) {
 226         die "$0: Failed to make temp directory: $tmpdir\n"
 227             if ( $! != EEXIST );
 228         undef $tmpdir;
 229     }
 230 }
 231
 232 $cfgfile = $tmpdir.'/mtools.conf';
 233 $imglink = $tmpdir.'/disk.img';
 234 die "$0: Failed to create symlink $imglink\n"
 235     if ( !symlink(absolute_path($file), $imglink) );
 236
 237 $header_size = ($opt{'d'} ? 128 : 0);
 238
 239 # Start of filesystem
 240 $offset = $s*512 + $header_size;
 241
 242 # Start of partition table entry
 243 $pstart = $header_size + 446 + 16*($pentry-1);
 244
 245 open(MCONFIG, "> ${cfgfile}") or die "$0: Cannot make mtools config\n";
 246 print MCONFIG "drive z:\n";
 247 print MCONFIG "file=\"${imglink}\"\n";
 248 print MCONFIG "cylinders=${c}\n";
 249 print MCONFIG "heads=${h}\n";
 250 print MCONFIG "sectors=${s}\n";
 251 print MCONFIG "offset=${offset}\n";
 252 print MCONFIG "mformat_only\n";
 253 close(MCONFIG);
 254
 255 # Output the filesystem offset to stdout if appropriate
 256 if ( $opt{'o'} ) {
 257     print $offset, "\n";
 258 }
 259
 260 $ENV{'MTOOLSRC'} = $cfgfile;
 261 if ( $opt{'F'} ) {
 262     system('mformat', '-F', 'z:');
 263 } else {
 264     system('mformat', 'z:');
 265 }
 266
 267 # Clean up in /tmp
 268 unlink($cfgfile);
 269 unlink($imglink);
 270 rmdir($tmpdir);
 271
 272 # MTOOLS doesn't write the bsHiddenSecs field correctly
 273 seek(OUTPUT, $offset + 0x1c, 0);
 274 print OUTPUT pack("V", ($offset-$header_size)>>9);
 275
 276 # Set the partition type
 277 if ( $opt{'F'} ) {
 278     if ( $c > 1024 ) {
 279         $fstype = 0x0c;         # FAT32 LBA
 280     } else {
 281         $fstype = 0x0b;
 282     }
 283 } else {
 284     if ( $c > 1024 ) {
 285         $fstype = 0x0e;         # FAT16 LBA
 286     } elsif ( $psize > 65536 ) {
 287         $fstype = 0x06;         # FAT16 > 32MB
 288     } else {
 289         $fstype = 0x04;         # FAT16 <= 32MB
 290     }
 291     seek(OUTPUT, $offset + 0x36, 0);
 292     read(OUTPUT, $fsname, 8);
 293
 294     # FAT12: adjust partition type
 295     if ( $fsname eq 'FAT12   ' ) {
 296         $fstype = 0x01;         # FAT12
 297     }
 298 }
 299 seek(OUTPUT, $pstart+4, 0);
 300 print OUTPUT pack("C", $fstype);
 301
 302 flush OUTPUT;
 303
 304 # Just in case this is a block device, try to flush the partition table
 305 if ( $is_linux ) {
 306     ioctl(OUTPUT, $BLKRRPART, 0);
 307 };
 308
 309 exit 0;
 310 __END__
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