ISOLINUX: support for hybrid mode (CD-ROM/USB key)

Still a work in progress.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

2 files changed, 170 insertions, 1 deletions

diff --git a/utils/Makefile b/utils/Makefile
index 64f8236f..de8c9992 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -20,7 +20,7 @@ include $(topdir)/MCONFIG
 CFLAGS   = -W -Wall -Os -fomit-frame-pointer -D_FILE_OFFSET_BITS=64
 LDFLAGS  = -O2 -s
 
-TARGETS	 = mkdiskimage gethostip
+TARGETS	 = mkdiskimage isohybrid gethostip
 ASIS     = keytab-lilo lss16toppm md5pass ppmtolss16 sha1pass syslinux2ansi
 
 all: $(TARGETS)
@@ -32,6 +32,10 @@ mkdiskimage: mkdiskimage.in ../mbr/mbr.bin bin2hex.pl
 	$(PERL) bin2hex.pl < ../mbr/mbr.bin | cat mkdiskimage.in - > $@
 	chmod a+x $@
 
+isohybrid: isohybrid.in ../mbr/isohdpfx.bin bin2hex.pl
+	$(PERL) bin2hex.pl < ../mbr/isohdpfx.bin | cat isohybrid.in - > $@
+	chmod a+x $@
+
 gethostip: gethostip.o
 	$(CC) $(LDFLAGS) -o $@ $^
 
diff --git a/utils/isohybrid.in b/utils/isohybrid.in
new file mode 100644
index 00000000..a0487ca0
--- /dev/null
+++ b/utils/isohybrid.in
@@ -0,0 +1,165 @@
+#!/usr/bin/perl
+## -----------------------------------------------------------------------
+##
+##   Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
+##
+##   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 integer;
+use Fcntl;
+use Errno;
+use Cwd;
+use IO::Handle;			# For flush()
+
+# Use this fake geometry (zipdrive-style...)
+$h = 64; $s = 32;
+
+sub get_random() {
+    # Get a 32-bit random number
+    my $rfd, $rnd;
+    my $rid;
+
+    if (sysopen($rfd, '/dev/urandom', O_RDONLY) &&
+	sysread($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;
+}
+
+
+($file) = @ARGV;
+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";
+}
+
+# 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
+$cylsize = $h*$s*512;
+$frac = $imgsize % $cylsize;
+$padding = ($frac > 0) ? $cylsize - $frac : 0;
+$imgsize += $padding;
+$c = $imgsize/$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;
+}
+
+# Now $de_lba should contain the CD sector number for isolinux.bin
+seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";
+
+# Print the MBR and partition table
+$mbr = '';
+while ( $line = <DATA> ) {
+    chomp $line;
+    foreach $byte ( split(/\s+/, $line) ) {
+	$mbr .= chr(hex($byte));
+    }
+}
+if ( length($mbr) > 432 ) {
+    die "$0: Bad MBR code\n";
+}
+
+$mbr .= "\0" x (432 - length($mbr));
+
+$mbr .= pack("VV", $de_lba*4, 0); # Offset 432: LBA of isolinux.bin
+if (defined($id)) {
+    $id = to_int($id);
+} else {
+    $id = get_random();
+}
+$mbr .= pack("V", $id);		# Offset 440: MBR ID
+$mbr .= "\0\0";			# Offset 446: actual partition table
+
+# Print partition table
+$psize = $c*$h*$s-$s;
+$bhead   = 0;
+$bsect   = 1;
+$bcyl    = 0;
+$ehead   = $h-1;
+$esect   = $s + ((($cc-1) & 0x300) >> 2);
+$ecyl    = ($cc-1) & 0xff;
+$fstype  = 0x83;		# Linux (any better ideas?)
+$pentry  = 1;
+if ( $c > 1024 ) {
+    $fstype = 0x0e;
+} elsif ( $psize > 65536 ) {
+    $fstype = 0x06;
+} else {
+    $fstype = 0x04;
+}
+for ( $i = 1 ; $i <= 4 ; $i++ ) {
+    if ( $i == $pentry ) {
+	$mbr .= pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype,
+		     $ehead, $esect, $ecyl, $s, $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__