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-rw-r--r--utils/isohybrid.in14
1 files changed, 8 insertions, 6 deletions
diff --git a/utils/isohybrid.in b/utils/isohybrid.in
index e98c59f6..83f9dc02 100644
--- a/utils/isohybrid.in
+++ b/utils/isohybrid.in
@@ -100,6 +100,13 @@ if ($c > 1024) {
$cc = $c;
}
+# Preserve id when run again
+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: $!\n";
@@ -117,12 +124,7 @@ if ( length($mbr) > 432 ) {
$mbr .= "\0" x (432 - length($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 .= $id; # Offset 440: MBR ID
$mbr .= "\0\0"; # Offset 446: actual partition table
# Print partition table