isohybrid: make the -offset option actually work

Actually implement the -offset option.  Credit for the patch goes to
"cmdr from the gparted-forum", reported by
Sven-Hendrik Haase <sh@lutzhaase.com>.

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

diff --git a/utils/isohybrid.in b/utils/isohybrid.in
index 0726bed..a127784 100644 (file)
--- a/utils/isohybrid.in
+++ b/utils/isohybrid.in
@@ -221,7 +221,7 @@ $mbr .= "\0\0";                             # Offset 446: actual partition table
 
 # Print partition table
 $offset  = $opt{'offset'};
-$psize   = $c*$h*$s;
+$psize   = $c*$h*$s - $offset;
 $bhead   = int($offset/$s) % $h;
 $bsect   = ($offset % $s) + 1;
 $bcyl    = int($offset/($h*$s));
@@ -236,7 +236,7 @@ $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, 0, $psize);
+                    $ehead, $esect, $ecyl, $offset, $psize);
     } else {
        $mbr .= "\0" x 16;
     }