Support FIXED_DISK_IDENTIFIERS option, useful for reproducible builds

Credit goes got Thorsten Staerk for his help on stackexchange.
(https://unix.stackexchange.com/questions/111414/how-to-change-the-disk-signature-of-a-raw-image)

diff --git a/config b/config
index 6efc119..53ff8ec 100644 (file)
--- a/config
+++ b/config
@@ -201,4 +201,9 @@
 # Default: '/etc/debootstrap/install_notes' (empty file).
 # INSTALL_NOTES='/etc/debootstrap/install_notes'
 
+# Use fixed disk identifiers for Virtual Machine builds.
+# Useful for reproducible builds.
+# Default: 'no'
+# FIXED_DISK_IDENTIFIERS='yes'
+
 ## END OF FILE #################################################################

diff --git a/grml-debootstrap b/grml-debootstrap
index 147465a..fd63e7d 100755 (executable)
--- a/grml-debootstrap
+++ b/grml-debootstrap
@@ -39,6 +39,7 @@ MNTPOINT="/mnt/debootstrap.$$"
 [ -n "$TUNE2FS" ] || TUNE2FS='tune2fs -c0 -i0'
 [ -n "$UPGRADE_SYSTEM" ] || UPGRADE_SYSTEM='yes'
 [ -n "$VMSIZE" ] || VMSIZE="2G"
+[ -n "$FIXED_DISK_IDENTIFIERS" ] || FIXED_DISK_IDENTIFIERS="no"
 
 # inside the chroot system locales might not be available, so use minimum:
 export LANG=C
@@ -887,6 +888,12 @@ mkfs() {
        einfo "Running $MKFS on $TARGET"
        $MKFS $TARGET ; RC=$?
 
+       if [ "$FIXED_DISK_IDENTIFIERS" = "yes" ] ; then
+         einfo "Changing disk uuid for $TARGET to fixed (non-random) value using tune2fs"
+         tune2fs "$TARGET" -U 26ada0c0-1165-4098-884d-aafd2220c2c6
+         eend $?
+       fi
+
        # make sure /dev/disk/by-uuid/... is up2date, otherwise grub
        # will fail to detect the uuid in the chroot
        if echo "$TARGET" | grep -q "/dev/md" ; then
@@ -961,6 +968,14 @@ prepare_vm() {
   qemu-img create -f raw "${TARGET}" "${VMSIZE}"
   echo 4 66 | /usr/share/grml-debootstrap/bootgrub.mksh -A | dd of="$TARGET" conv=notrunc
   dd if=/dev/zero bs=1 conv=notrunc count=64 seek=446 of="$TARGET"
+  if [ "$FIXED_DISK_IDENTIFIERS" = "yes" ] ; then
+    einfo "Adjusting disk signature to a fixed (non-random) value"
+    MBRTMPFILE=$(mktemp)
+    dd if="${TARGET}" of="${MBRTMPFILE}" bs=512 count=1
+    echo -en "\x41\x41\x41\x41\x41" | dd of="${MBRTMPFILE}" conv=notrunc seek=440 bs=1
+    dd if="${MBRTMPFILE}" of="${TARGET}" conv=notrunc
+    eend $?
+  fi
   parted -s "${TARGET}" 'mkpart primary ext3 2M -1'
 
   # if dm-mod isn't available then kpartx will fail with