#!/usr/bin/perl
# isohybrid-acritox - written by Andreas Loibl <andreas@andreas-loibl.de>
# 
# Post-process a hybrid-ISO-image generated with isohybrid-bg2
# by injecting an "Apple Partition Map" into the image and appending a HFS+-partiton
# and using a FAT-partition embedded as file into the ISO9660 to allow "hybrid booting"
# as CD-ROM (EFI or El Torito) or as a hard-drive on Intel-Macs (EFI) and PCs (EFI or MBR).

$bs=0x0200; $block0='45520200eb5f90'; #  512  -  add    (%eax),%al
$bs=0x0400; $block0='45520400eb5f90'; # 1024  -  add    $0x0,%al
$bs=0x0800; $block0='45520800eb5f90'; # 2048  -  or     %al,(%bx,%si)

# Apple Partition Map entries:
$pm1='504d000000000003000000010000000f4170706c650000000000000000000000000000000000000000000000000000004170706c655f706172746974696f6e5f6d617000000000000000000000000000000000000000000f00000003'; # Apple_partition_map
$pm2='504d00000000000300000400000005006469736b20696d616765000000000000000000000000000000000000000000004170706c655f4846530000000000000000000000000000000000000000000000000000000000040040000033'; # Apple_HFS
$pm3='504d00000000000300000001000004004b414e4f5449585f454649000000000000000000000000000000000000000000444f535f4641545f313200000000000000000000000000000000000000000000000000000000040040000033'; # DOS_FAT_12

die "Usage: $0 <isohybrid-bg2.iso> <HFS+-image>\n" if $#ARGV != 1;

# name of the first file in the ISO
$first_filename="boot.catalog"; 

# name of the file containing the EFI-FAT-image
$filename="boot.efi.img";

# name of the file to be used as ISO-offset-destination
$embiso_filename="boot.iso.img";

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

open(PART, "< $part\0") or die "$0: cannot open $part: $!\n";
binmode PART;

# Check if image has already been "patched" (i.e. it has the APM signature from $block0)
seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";
read(FILE, $test, 2) == 2 or die "$0: $file: read error\n";
die "$file seems to have an APM signature already...\n" if($test eq 'ER');

# Check if image is a isohybrid-bg2 image (i.e. it has GRUB in its MBR)
seek(FILE, 0x180, SEEK_SET) or die "$0: $file: $!\n";
read(FILE, $test, 4) == 4 or die "$0: $file: read error\n";
die "$file seems not to have GRUB in its MBR (is this a isohybrid-bg2 image?)\n" if($test ne 'GRUB');

# Check if partition contains a HFS+ filesystem
seek(PART, 0x400, SEEK_SET) or die "$0: $file: $!\n";
read(PART, $test, 2) == 2 or die "$0: $file: read error\n";
die "$part doesn't seem to contain a HFS+ filesystem\n" if($test ne 'H+');

$start = int(`isoinfo -R -s -l -i "$file" | awk '/$filename/{print \$10}'`);
if (!$start) {
    die "$0: $filename: cannot determine position of file\n";
}

$embiso_start = int(`isoinfo -R -s -l -i "$file" | awk '/$embiso_filename/{print \$10}'`);
if (!$embiso_start) {
    die "$0: $embiso_filename: cannot determine position of file\n";
}

$start_of_files = int(`isoinfo -R -s -l -i "$file" | awk '/$first_filename/{print \$10}'`);
if (!$start_of_files) {
    die "$0: $first_filename: cannot determine position of file\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 $bs*512
$cylsize = $bs*512;
$frac = $imgsize % $cylsize;
$padding = ($frac > 0) ? $cylsize - $frac : 0;
$imgsize += $padding;

# Get the total size of the partiton
(@partstat = stat(PART)) or die "$0: $part: $!\n";
$partsize = $partstat[7];
if (!$partsize) {
    die "$0: $part: cannot determine length of file\n";
}

seek(FILE, 0, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('H*',$block0);
seek(FILE, $bs*1, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('H*',$pm1);
seek(FILE, $bs*2, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('H*',$pm2);
seek(FILE, $bs*3, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('H*',$pm3);

# 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;
}

# Append partition to image
seek(PART, 0, SEEK_SET) or die "$0: $file: $!\n";
read PART, $partition, $partsize;
print FILE $partition;

# Pad the partition to a fake cylinder boundary
$frac = $partsize % $cylsize;
$padding = ($frac > 0) ? $cylsize - $frac : 0;
if ($padding) {
    print FILE "\0" x $padding;
}
$partsize += $padding;

use integer;
$lba = $start*4;
$embiso_lba = $embiso_start*4;
$psize = $imgsize/512 - $lba;

# Adjust $pm2 (Apple_HFS)
# "physical block start" and "physical block count" of partition:
seek(FILE, $bs*2+8, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('NN', $imgsize/$bs, $partsize/$bs);
# "logical block start" and "logical block count" of partition:
seek(FILE, $bs*2+80, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('NN', 0, $partsize/$bs);

# Adjust $pm3 (DOS_FAT_12)
# "physical block start" and "physical block count" of partition:
seek(FILE, $bs*3+8, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('NN', $lba*512/$bs, $psize*512/$bs);
# "logical block start" and "logical block count" of partition:
seek(FILE, $bs*3+80, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack('NN', 0, $psize*512/$bs);

$imgsize += $partsize;
seek(FILE, $imgsize, SEEK_SET) or die "$0: $file: $!\n";

# Target image size: round up to a multiple of 1MB
$cylsize = 64*32*512; # 1MB
$frac = $imgsize % $cylsize;
$padding = ($frac > 0) ? $cylsize - $frac : 0;
$imgsize += $padding;
if ($padding) {
    print FILE "\0" x $padding;
}

# Done...
close(PART);

# Calculate partiton table (MBR)
$psize = $embiso_lba - $lba;
$h = 64; $s = 32;
$hpc = 32; $spt = 63;
$bcyl = $lba / ($spt * $hpc);
$bhead = ($lba / $spt) % $hpc;
$bsect = ($lba % $spt) + 1;
$cylsize = $h*$s*512;
$c = $imgsize/$cylsize;
if ($c > 1024) {
    $cc = 1024;
} else {
    $cc = $c;
}
$ehead   = $h-1;
$esect   = $s + ((($cc-1) & 0x300) >> 2);
$ecyl    = ($cc-1) & 0xff;

# Adjust MBR partition table
$fstype  = 0xEF;
$pentry  = 1;

seek(FILE, 430+16*$pentry, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype, $ehead, $esect, $ecyl, $lba, $psize);

$psize = $imgsize/512 - $embiso_lba;
$bcyl = $embiso_lba / ($spt * $hpc);
$bhead = ($embiso_lba / $spt) % $hpc;
$bsect = ($embiso_lba % $spt) + 1;
$ehead   = $h-1;
$esect   = $s + ((($cc-1) & 0x300) >> 2);
$ecyl    = ($cc-1) & 0xff;

$fstype  = 0x83;
$pentry  = 2;

seek(FILE, 430+16*$pentry, SEEK_SET) or die "$0: $file: $!\n";
print FILE pack("CCCCCCCCVV", 0x80, $bhead, $bsect, $bcyl, $fstype, $ehead, $esect, $ecyl, $embiso_lba, $psize);

# Done...
close(FILE);

# Embed a copy of the ISO filesystem into the ISO at the second partition (= start_of_block1)
print("dd if=$file bs=2048 count=$start_of_files of=$file seek=$embiso_start conv=notrunc\n");
system("dd if=$file bs=2048 count=$start_of_files of=$file seek=$embiso_start conv=notrunc");

$off = $bs*$embiso_start;
$diff = $embiso_start;

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

sub write_val
{
	my($offset, $value) = @_;
	$cur = tell(FILE);
	$offset += $cur if $offset < 0;
	printf("byte-offset: 0x%X -> 0x%X\n", $offset, $offset-$diff*$bs);
	seek(FILE, $offset, SEEK_SET);
	print FILE $value;
	seek(FILE, $cur, SEEK_SET);
}

$off_pvd = $off+0x8000;
do
{
	seek(FILE, $off_pvd, SEEK_SET) or die "$0: $file: $!\n";
	read(FILE, $voldesc_head, 7) > 0 or die "$0: $file: read error\n";
	($type, $magic, $version) = unpack("Ca[5]C", $voldesc_head);
	if($type == 1)
	{
		seek(FILE, 0x97, 1);
		read(FILE, $voldesc, 8) > 0 or die "$0: $file: read error\n";
		($first_sector, $first_sector_be) = unpack("VN", $voldesc);
		seek(FILE, $off+$first_sector*$bs, SEEK_SET) or die "$0: $file: $!\n";
		printf("root-directory entry at 0x%X:\n", tell(FILE));
		read(FILE, $bytes, 1) > 0 or die "$0: $file: read error\n";
		$bytes = unpack("C", $bytes) - 1; $sector = 0;
		do {
			printf("SUSP entry - %u bytes (0x%X)\n", $bytes+1, $bytes+1);
			do {
				$wp = tell(FILE);
				$bytes -= read(FILE, $voldesc, 32);
				($ext_sectors, $lba, $lba_be, $size, $size_be, $uu, $namelen)
					= unpack("CVNVNa[14]C", $voldesc);
				if($lba > $diff)
				{
					printf("LBA 0x%x -> LBA 0x%x\n", $lba, $lba - $diff);
					write_val($wp+1, pack("VN", $lba - $diff, $lba - $diff));
				}
				$namelen++ if $namelen % 2 == 0;
				$bytes -= read(FILE, $name, $namelen);
				$filename = unpack("Z*", $name);
				print("file: $filename\n");
				# hide the second ISOFS-EFI-partition from the Mac Bootloader by f***ing up the "EFI" directory entry
				write_val(-$namelen, pack("Z*", ".PC")) if($filename eq "EFI");

				$bytes -= read(FILE, $sua_head, 4);
				($sig, $len, $version) = unpack("a[2]CC", $sua_head);
				$len -= 4;
				$bytes -= read(FILE, $data, $len);
				do {
					$bytes -= read(FILE, $sua_head, 4);
					($sig, $len, $version) = unpack("a[2]CCa", $sua_head);
					$len -= 4;
					$bytes -= read(FILE, $data, $len);
					if($sig eq "CE")
					{
						($sua_block, $uu1, $sua_pos, $uu2, $sua_size, $uu3) = unpack("VNVNVN", $data);
						printf("CE is at LBA 0x%X -> 0x%x\n", $sua_block);
					}
				} while($bytes > 4);
				$bytes -= read(FILE, $uu, $bytes) if $bytes > 0; # skip bytes (if unaligned)
				read(FILE, $bytes, 1) > 0 or die "$0: $file: read error\n";
				$bytes = unpack("C", $bytes) - 1;
				printf("SUSP Entry - %u bytes (0x%X)\n", $bytes+1, $bytes+1);
			} while $bytes > 0;
			$sector++;
			seek(FILE, $off+$first_sector*$bs+$sector*$bs, SEEK_SET) or die "$0: $file: $!\n";
			printf("\ndirectory entry at 0x%X:\n", tell(FILE));
			read(FILE, $bytes, 1) > 0 or break;
			$bytes = unpack("C", $bytes) - 1;
		} while $bytes != 0x21 && $bytes != 0;
	}
	$off_pvd+=$bs;
} while $type != 255;

# Done...
close(FILE);

exit 0;