utils/isohybrid.in - pub/scm/boot/syslinux/syslinux - Git at Google

 #!/usr/bin/perl
 ## -----------------------------------------------------------------------
 ##
 ##   Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
 ##   Copyright 2009 Intel Corporation; author: H. Peter Anvin
 ##
 ##   This program is free software; you can redistribute it and/or modify
 ##   it under the terms of the GNU General Public License as published by
 ##   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 ##   Boston MA 02111-1307, USA; either version 2 of the License, or
 ##   (at your option) any later version; incorporated herein by reference.
 ##
 ## -----------------------------------------------------------------------

 #
 # Post-process an ISO 9660 image generated with mkisofs/genisoimage
 # to allow "hybrid booting" as a CD-ROM or as a hard disk.
 #

 use bytes;
 use Fcntl;

 # User-specifyable options
 %opt = (
     # Fake geometry (zipdrive-style...)
     'h'      => 64,
     's'      => 32,
     # Partition number
     'entry'  => 1,
     # Partition offset
     'offset' => 0,
     # Partition type
     'type'   => 0x17,		# "Windows hidden IFS"
     # MBR ID
     'id'     => undef,
 );

 %valid_range = (
     'h'      => [1, 256],
     's'      => [1, 63],
     'entry'  => [1, 4],
     'offset' => [0, 64],
     'type'   => [0, 255],
     'id'     => [0, 0xffffffff],
     'hd0'    => [0, 2],
     'partok' => [0, 1],
 );

 # Boolean options just set other options
 %bool_opt = (
     'nohd0'    => ['hd0', 0],
     'forcehd0' => ['hd0', 1],
     'ctrlhd0'  => ['hd0', 2],
     'nopartok' => ['partok', 0],
     'partok'   => ['partok', 1],
 );

 sub usage() {
     print STDERR "Usage: $0 [options] filename.iso\n",
     "Options:\n",
     "  -h          Number of default geometry heads\n",
     "  -s          Number of default geometry sectors\n",
     "  -entry      Specify partition entry number (1-4)\n",
     "  -offset     Specify partition offset (default 0)\n",
     "  -type       Specify partition type (default 0x17)\n",
     "  -id         Specify MBR ID (default random)\n",
     "  -forcehd0   Always assume we are loaded as disk ID 0\n",
     "  -ctrlhd0    Assume disk ID 0 if the Ctrl key is pressed\n",
     "  -partok     Allow booting from within a partition\n";
     exit 1;
 }

 # Parse a C-style integer (decimal/octal/hex)
 sub doh($) {
     my($n) = @_;
     return ($n =~ /^0/) ? oct $n : $n+0;
 }

 sub get_random() {
     # Get a 32-bit random number
     my $rfd, $rnd;
     my $rid;

     if (open($rfd, "< /dev/urandom\0") && read($rfd, $rnd, 4) == 4) {
 	$rid = unpack("V", $rnd);
     }

     close($rfd) if (defined($rfd));
     return $rid if (defined($rid));

     # This sucks but is better than nothing...
     return ($$+time()) & 0xffffffff;
 }

 sub get_hex_data() {
     my $mbr = '';
     my $line, $byte;
     while ( $line = <DATA> ) {
 	chomp $line;
 	last if ($line eq '*');
 	foreach $byte ( split(/\s+/, $line) ) {
 	    $mbr .= chr(hex($byte));
 	}
     }
     return $mbr;
 }

 while ($ARGV[0] =~ /^\-(.*)$/) {
     $o = $1;
     shift @ARGV;
     if (defined($bool_opt{$o})) {
 	($o, $v) = @{$bool_opt{$o}};
 	$opt{$o} = $v;
     } elsif (exists($opt{$o})) {
 	$opt{$o} = doh(shift @ARGV);
 	if (defined($valid_range{$o})) {
 	    ($l, $h) = @{$valid_range{$o}};
 	    if ($opt{$o} < $l || $opt{$o} > $h) {
 		die "$0: valid values for the -$o parameter are $l to $h\n";
 	    }
 	}
     } else {
 	usage();
     }
 }

 ($file) = @ARGV;

 if (!defined($file)) {
     usage();
 }

 open(FILE, "+< $file\0") or die "$0: cannot open $file: $!\n";
 binmode FILE;

 #
 # First, actually figure out where mkisofs hid isolinux.bin
 #
 seek(FILE, 17*2048, SEEK_SET) or die "$0: $file: $!\n";
 read(FILE, $boot_record, 2048) == 2048 or die "$0: $file: read error\n";
 ($br_sign, $br_cat_offset) = unpack("a71V", $boot_record);
 if ($br_sign ne ("\0CD001\1EL TORITO SPECIFICATION" . ("\0" x 41))) {
     die "$0: $file: no boot record found\n";
 }
 seek(FILE, $br_cat_offset*2048, SEEK_SET) or die "$0: $file: $!\n";
 read(FILE, $boot_cat, 2048) == 2048 or die "$0: $file: read error\n";

 # We must have a Validation Entry followed by a Default Entry...
 # no fanciness allowed for the Hybrid mode [XXX: might relax this later]
 @ve = unpack("v16", $boot_cat);
 $cs = 0;
 for ($i = 0; $i < 16; $i++) {
     $cs += $ve[$i];
 }
 if ($ve[0] != 0x0001 || $ve[15] != 0xaa55 || $cs & 0xffff) {
     die "$0: $file: invalid boot catalog\n";
 }
 ($de_boot, $de_media, $de_seg, $de_sys, $de_mbz1, $de_count,
  $de_lba, $de_mbz2) = unpack("CCvCCvVv", substr($boot_cat, 32, 32));
 if ($de_boot != 0x88 || $de_media != 0 ||
     ($de_segment != 0 && $de_segment != 0x7c0) || $de_count != 4) {
     die "$0: $file: unexpected boot catalog parameters\n";
 }

 # Now $de_lba should contain the CD sector number for isolinux.bin
 seek(FILE, $de_lba*2048+0x40, SEEK_SET) or die "$0: $file: $!\n";
 read(FILE, $ibsig, 4);
 if ($ibsig ne "\xfb\xc0\x78\x70") {
     die "$0: $file: bootloader does not have a isolinux.bin hybrid signature.".
         "Note that isolinux-debug.bin does not support hybrid booting.\n";
 }

 # Get the total size of the image
 (@imgstat = stat(FILE)) or die "$0: $file: $!\n";
 $imgsize = $imgstat[7];
 if (!$imgsize) {
     die "$0: $file: cannot determine length of file\n";
 }
 # Target image size: round up to a multiple of $h*$s*512
 $h = $opt{'h'};
 $s = $opt{'s'};
 $cylsize = $h*$s*512;
 $frac = $imgsize % $cylsize;
 $padding = ($frac > 0) ? $cylsize - $frac : 0;
 $imgsize += $padding;
 $c = int($imgsize/$cylsize);
 if ($c > 1024) {
     print STDERR "Warning: more than 1024 cylinders ($c).\n";
     print STDERR "Not all BIOSes will be able to boot this device.\n";
     $cc = 1024;
 } else {
     $cc = $c;
 }

 # Preserve id when run again
 if (defined($opt{'id'})) {
     $id = pack("V", doh($opt{'id'}));
 } else {
     seek(FILE, 440, SEEK_SET) or die "$0: $file: $!\n";
     read(FILE, $id, 4);
     if ($id eq "\x00\x00\x00\x00") {
 	$id = pack("V", get_random());
     }
 }

 # Print the MBR and partition table
 seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";

 for ($i = 0; $i <= $opt{'hd0'}+3*$opt{'partok'}; $i++) {
     $mbr = get_hex_data();
 }
 if ( length($mbr) > 432 ) {
     die "$0: Bad MBR code\n";
 }

 $mbr .= "\0" x (432 - length($mbr));

 $mbr .= pack("VV", $de_lba*4, 0); 	# Offset 432: LBA of isolinux.bin
 $mbr .= $id;				# Offset 440: MBR ID
 $mbr .= "\0\0";				# Offset 446: actual partition table

 # Print partition table
 $offset  = $opt{'offset'};
 $psize   = $c*$h*$s - $offset;
 $bhead   = int($offset/$s) % $h;
 $bsect   = ($offset % $s) + 1;
 $bcyl    = int($offset/($h*$s));
 $bsect  += ($bcyl & 0x300) >> 2;
 $bcyl   &= 0xff;
 $ehead   = $h-1;
 $esect   = $s + ((($cc-1) & 0x300) >> 2);
 $ecyl    = ($cc-1) & 0xff;
 $fstype  = $opt{'type'};	# Partition type
 $pentry  = $opt{'entry'};	# Partition slot

 for ( $i = 1 ; $i <= 4 ; $i++ ) {
     if ( $i == $pentry ) {
 	$mbr .= pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype,
 		     $ehead, $esect, $ecyl, $offset, $psize);
     } else {
 	$mbr .= "\0" x 16;
     }
 }
 $mbr .= "\x55\xaa";

 print FILE $mbr;

 # Pad the image to a fake cylinder boundary
 seek(FILE, $imgstat[7], SEEK_SET) or die "$0: $file: $!\n";
 if ($padding) {
     print FILE "\0" x $padding;
 }

 # Done...
 close(FILE);

 exit 0;
 __END__
	#!/usr/bin/perl
	## -----------------------------------------------------------------------
	##
	## Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
	## Copyright 2009 Intel Corporation; author: H. Peter Anvin
	##
	## This program is free software; you can redistribute it and/or modify
	## it under the terms of the GNU General Public License as published by
	## the Free Software Foundation, Inc., 53 Temple Place Ste 330,
	## Boston MA 02111-1307, USA; either version 2 of the License, or
	## (at your option) any later version; incorporated herein by reference.
	##
	## -----------------------------------------------------------------------

	#
	# Post-process an ISO 9660 image generated with mkisofs/genisoimage
	# to allow "hybrid booting" as a CD-ROM or as a hard disk.
	#

	use bytes;
	use Fcntl;

	# User-specifyable options
	%opt = (
	# Fake geometry (zipdrive-style...)
	'h' => 64,
	's' => 32,
	# Partition number
	'entry' => 1,
	# Partition offset
	'offset' => 0,
	# Partition type
	'type' => 0x17, # "Windows hidden IFS"
	# MBR ID
	'id' => undef,
	);

	%valid_range = (
	'h' => [1, 256],
	's' => [1, 63],
	'entry' => [1, 4],
	'offset' => [0, 64],
	'type' => [0, 255],
	'id' => [0, 0xffffffff],
	'hd0' => [0, 2],
	'partok' => [0, 1],
	);

	# Boolean options just set other options
	%bool_opt = (
	'nohd0' => ['hd0', 0],
	'forcehd0' => ['hd0', 1],
	'ctrlhd0' => ['hd0', 2],
	'nopartok' => ['partok', 0],
	'partok' => ['partok', 1],
	);

	sub usage() {
	print STDERR "Usage: $0 [options] filename.iso\n",
	"Options:\n",
	" -h Number of default geometry heads\n",
	" -s Number of default geometry sectors\n",
	" -entry Specify partition entry number (1-4)\n",
	" -offset Specify partition offset (default 0)\n",
	" -type Specify partition type (default 0x17)\n",
	" -id Specify MBR ID (default random)\n",
	" -forcehd0 Always assume we are loaded as disk ID 0\n",
	" -ctrlhd0 Assume disk ID 0 if the Ctrl key is pressed\n",
	" -partok Allow booting from within a partition\n";
	exit 1;
	}

	# Parse a C-style integer (decimal/octal/hex)
	sub doh($) {
	my($n) = @_;
	return ($n =~ /^0/) ? oct $n : $n+0;
	}

	sub get_random() {
	# Get a 32-bit random number
	my $rfd, $rnd;
	my $rid;

	if (open($rfd, "< /dev/urandom\0") && read($rfd, $rnd, 4) == 4) {
	$rid = unpack("V", $rnd);
	}

	close($rfd) if (defined($rfd));
	return $rid if (defined($rid));

	# This sucks but is better than nothing...
	return ($$+time()) & 0xffffffff;
	}

	sub get_hex_data() {
	my $mbr = '';
	my $line, $byte;
	while ( $line = <DATA> ) {
	chomp $line;
	last if ($line eq '*');
	foreach $byte ( split(/\s+/, $line) ) {
	$mbr .= chr(hex($byte));
	}
	}
	return $mbr;
	}

	while ($ARGV[0] =~ /^\-(.*)$/) {
	$o = $1;
	shift @ARGV;
	if (defined($bool_opt{$o})) {
	($o, $v) = @{$bool_opt{$o}};
	$opt{$o} = $v;
	} elsif (exists($opt{$o})) {
	$opt{$o} = doh(shift @ARGV);
	if (defined($valid_range{$o})) {
	($l, $h) = @{$valid_range{$o}};
	if ($opt{$o} < $l \|\| $opt{$o} > $h) {
	die "$0: valid values for the -$o parameter are $l to $h\n";
	}
	}
	} else {
	usage();
	}
	}

	($file) = @ARGV;

	if (!defined($file)) {
	usage();
	}

	open(FILE, "+< $file\0") or die "$0: cannot open $file: $!\n";
	binmode FILE;

	#
	# First, actually figure out where mkisofs hid isolinux.bin
	#
	seek(FILE, 17*2048, SEEK_SET) or die "$0: $file: $!\n";
	read(FILE, $boot_record, 2048) == 2048 or die "$0: $file: read error\n";
	($br_sign, $br_cat_offset) = unpack("a71V", $boot_record);
	if ($br_sign ne ("\0CD001\1EL TORITO SPECIFICATION" . ("\0" x 41))) {
	die "$0: $file: no boot record found\n";
	}
	seek(FILE, $br_cat_offset*2048, SEEK_SET) or die "$0: $file: $!\n";
	read(FILE, $boot_cat, 2048) == 2048 or die "$0: $file: read error\n";

	# We must have a Validation Entry followed by a Default Entry...
	# no fanciness allowed for the Hybrid mode [XXX: might relax this later]
	@ve = unpack("v16", $boot_cat);
	$cs = 0;
	for ($i = 0; $i < 16; $i++) {
	$cs += $ve[$i];
	}
	if ($ve[0] != 0x0001 \|\| $ve[15] != 0xaa55 \|\| $cs & 0xffff) {
	die "$0: $file: invalid boot catalog\n";
	}
	($de_boot, $de_media, $de_seg, $de_sys, $de_mbz1, $de_count,
	$de_lba, $de_mbz2) = unpack("CCvCCvVv", substr($boot_cat, 32, 32));
	if ($de_boot != 0x88 \|\| $de_media != 0 \|\|
	($de_segment != 0 && $de_segment != 0x7c0) \|\| $de_count != 4) {
	die "$0: $file: unexpected boot catalog parameters\n";
	}

	# Now $de_lba should contain the CD sector number for isolinux.bin
	seek(FILE, $de_lba*2048+0x40, SEEK_SET) or die "$0: $file: $!\n";
	read(FILE, $ibsig, 4);
	if ($ibsig ne "\xfb\xc0\x78\x70") {
	die "$0: $file: bootloader does not have a isolinux.bin hybrid signature.".
	"Note that isolinux-debug.bin does not support hybrid booting.\n";
	}

	# Get the total size of the image
	(@imgstat = stat(FILE)) or die "$0: $file: $!\n";
	$imgsize = $imgstat[7];
	if (!$imgsize) {
	die "$0: $file: cannot determine length of file\n";
	}
	# Target image size: round up to a multiple of $h$s512
	$h = $opt{'h'};
	$s = $opt{'s'};
	$cylsize = $h$s512;
	$frac = $imgsize % $cylsize;
	$padding = ($frac > 0) ? $cylsize - $frac : 0;
	$imgsize += $padding;
	$c = int($imgsize/$cylsize);
	if ($c > 1024) {
	print STDERR "Warning: more than 1024 cylinders ($c).\n";
	print STDERR "Not all BIOSes will be able to boot this device.\n";
	$cc = 1024;
	} else {
	$cc = $c;
	}

	# Preserve id when run again
	if (defined($opt{'id'})) {
	$id = pack("V", doh($opt{'id'}));
	} else {
	seek(FILE, 440, SEEK_SET) or die "$0: $file: $!\n";
	read(FILE, $id, 4);
	if ($id eq "\x00\x00\x00\x00") {
	$id = pack("V", get_random());
	}
	}

	# Print the MBR and partition table
	seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";

	for ($i = 0; $i <= $opt{'hd0'}+3*$opt{'partok'}; $i++) {
	$mbr = get_hex_data();
	}
	if ( length($mbr) > 432 ) {
	die "$0: Bad MBR code\n";
	}

	$mbr .= "\0" x (432 - length($mbr));

	$mbr .= pack("VV", $de_lba*4, 0); # Offset 432: LBA of isolinux.bin
	$mbr .= $id; # Offset 440: MBR ID
	$mbr .= "\0\0"; # Offset 446: actual partition table

	# Print partition table
	$offset = $opt{'offset'};
	$psize = $c$h$s - $offset;
	$bhead = int($offset/$s) % $h;
	$bsect = ($offset % $s) + 1;
	$bcyl = int($offset/($h*$s));
	$bsect += ($bcyl & 0x300) >> 2;
	$bcyl &= 0xff;
	$ehead = $h-1;
	$esect = $s + ((($cc-1) & 0x300) >> 2);
	$ecyl = ($cc-1) & 0xff;
	$fstype = $opt{'type'}; # Partition type
	$pentry = $opt{'entry'}; # Partition slot

	for ( $i = 1 ; $i <= 4 ; $i++ ) {
	if ( $i == $pentry ) {
	$mbr .= pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype,
	$ehead, $esect, $ecyl, $offset, $psize);
	} else {
	$mbr .= "\0" x 16;
	}
	}
	$mbr .= "\x55\xaa";

	print FILE $mbr;

	# Pad the image to a fake cylinder boundary
	seek(FILE, $imgstat[7], SEEK_SET) or die "$0: $file: $!\n";
	if ($padding) {
	print FILE "\0" x $padding;
	}

	# Done...
	close(FILE);

	exit 0;
	__END__