init="/sbin/init"
root_ro=0
root_rw=0
root=""
rootflags=""
rootfstype=""

SQUASHED="/mnt/slackware.dat"

# Parse kernel commandline options
#
for o in `cat /proc/cmdline` ; do
    case $o in
    init=*)
        init=${o#init=}
        ;;
    ro)
        root_ro=1
        ;;
    rw)
        root_rw=1
        ;;
    *)
        continue
        ;;
    esac
done

# Users can override rootfs target on the kernel commandline
#
for o in `cat /proc/cmdline` ; do
    case $o in
    root=*)
        root=${o#root=}
        ;;
    rootflags=*)
        rootflags=${o#rootflags=}
        ;;
    rootfstype=*)
        rootfstype=${o#rootfstype=}
        ;;
    esac
done

waitforsymlink=0
# generate udev rules to generate /dev/root symlink
if [ -z $root ] ; then
    root=/dev/something
else
    case $root in
        /dev/disk/by-label/*)
            LABEL=${root#/dev/disk/by-label/}
            echo "SUBSYSTEM==\"block\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$LABEL\", SYMLINK+=\"root\"" > /etc/udev/rules.d/00-label.rules
            if [ "$quiet" != "1" ] ; then
                echo "Added udev rule 00-label.rules:"
                cat /etc/udev/rules.d/00-label.rules
            fi
            waitforsymlink=1
            thingtomount=/dev/root
            ;;
        CDLABEL=*)
            CDLABEL=${root#CDLABEL=}
            echo "KERNEL==\"hd[a-z]\", BUS==\"ide\", SYSFS{removable}==\"1\", ATTRS{media}==\"cdrom\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$CDLABEL\", SYMLINK+=\"root\"" > /etc/udev/rules.d/00-cdlabel.rules
            echo "KERNEL==\"sr[0-9]\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$CDLABEL\", SYMLINK+=\"root\"" >> /etc/udev/rules.d/00-cdlabel.rules
            echo "KERNEL==\"scd[0-9]\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$CDLABEL\", SYMLINK+=\"root\"" >> /etc/udev/rules.d/00-cdlabel.rules
            echo "KERNEL==\"pcd[0-9]\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$CDLABEL\", SYMLINK+=\"root\"" >> /etc/udev/rules.d/00-cdlabel.rules
            if [ "$quiet" != "1" ] ; then
                echo "Added udev rule 00-cdlabel.rules:"
                cat /etc/udev/rules.d/00-cdlabel.rules
            fi
            waitforsymlink=1
            thingtomount=/dev/root
            ;;
        LABEL=*)
            LABEL=${root#LABEL=}
            echo "SUBSYSTEM==\"block\", PROGRAM=\"/lib/udev/vol_id -l %N\", RESULT==\"$LABEL\", SYMLINK+=\"root\"" > /etc/udev/rules.d/00-label.rules
            if [ "$quiet" != "1" ] ; then
                echo "Added udev rule 00-label.rules:"
                cat /etc/udev/rules.d/00-label.rules
            fi
            waitforsymlink=1
            thingtomount=/dev/root
            ;;
        /dev/disk/by-id/*)
            UUID=${root#/dev/disk/by-id/}
            echo "SUBSYSTEM==\"block\", PROGRAM=\"/lib/udev/vol_id -u %N\", RESULT==\"$UUID\", SYMLINK+=\"root\"" > /etc/udev/rules.d/01-uuid.rules
            if [ "$quiet" != "1" ] ; then
                echo "Added udev rule 01-uuid.rules:"
                cat /etc/udev/rules.d/01-uuid.rules
            fi
            waitforsymlink=1
            thingtomount=/dev/root
            ;;
        UUID=*)
            UUID=${root#UUID=}
            echo "SUBSYSTEM==\"block\", PROGRAM=\"/lib/udev/vol_id -u %N\", RESULT==\"$UUID\", SYMLINK+=\"root\"" > /etc/udev/rules.d/01-uuid.rules
            if [ "$quiet" != "1" ] ; then
                echo "Added udev rule 01-uuid.rules:"
                cat /etc/udev/rules.d/01-uuid.rules
            fi
            waitforsymlink=1
            thingtomount=/dev/root
            ;;
        /dev/*)
            ln -s $root /dev/root
            thingtomount=$root
            ;;
        *)
            thingtomount=$root
            ;;
    esac
fi

echo "udev_log=\"error\"" >> /etc/udev/udev.conf

# rules for device-mapper
#
echo "KERNEL==\"device-mapper\", NAME=\"mapper/control\"" >> /etc/udev/rules.d/64-device-mapper.rules

/sbin/udevd --daemon

/sbin/udevadm trigger

/sbin/udevadm settle --timeout=30 || :

LIVE_BOOTDEV=`readlink /dev/root`

if [ "$quiet" != "1" ] ; then
   echo "mounting /dev/root"
   ls -l /dev/root
fi

if [ -z $rootfstype ] ; then
   rootfstype=auto
fi

if [ "x$root_ro" == "x1" ] ; then
   if [ -z $rootflags ] ; then
       rootflags="ro"
   else
       rootflags="$rootflags,ro"
   fi
fi

if [ "x$root_rw" == "x1" ] ; then
   if [ -z $rootflags ] ; then
       rootflags="rw"
   else
       rootflags="$rootflags,rw"
   fi
fi

if [ -z $rootflags ] ; then
    mountoptions=""
else
    mountoptions=" -o$rootflags"
fi

mount -n -t $rootfstype $mountoptions $thingtomount /mnt

SQUASHED_LOOPDEV=$( losetup -f )

losetup $SQUASHED_LOOPDEV $SQUASHED
mkdir -p /system
mount -n -t squashfs -o ro $SQUASHED_LOOPDEV /system

BASE_LOOPDEV=$( losetup -f )

losetup $BASE_LOOPDEV /system/slackware.ext2fs

# prepare an overlay file if not found
if [ ! -e /mnt/slackware.cow ]; then
    # create a sparse file for the overlay (512MB)
    dd if=/dev/null of=/mnt/slackware.cow bs=1024 count=1 seek=$((512*1024)) 2> /dev/null
fi

umount -l /system
umount -l /mnt

OVERLAY_LOOPDEV=$( losetup -f )

losetup $OVERLAY_LOOPDEV /mnt/slackware.cow

# set up the snapshot
echo 0 `blockdev --getsize $BASE_LOOPDEV` snapshot $BASE_LOOPDEV $OVERLAY_LOOPDEV p 8 | dmsetup create live-rw

# set up new /dev/root symlink
rm -f /dev/root
ln -s /dev/mapper/live-rw /dev/root

mount -n -t ext2 /dev/mapper/live-rw /mnt

# here you can modify the rw ext2 fs for testing if you don't want to respin the entire rootfs (which takes ages).
# Example
#
#  echo foo > /mnt/etc/bar.conf
#

# create rule so udev creates /dev/live symlink on real rootfs
if [ -d /mnt/lib/udev/rules.d ] ;then
  udevrulefn=$( ls /mnt/lib/udev/rules.d/50-udev* )
else
  udevrulefn=$( ls /mnt/etc/udev/rules.d/50-udev* )
fi

# add rules for loop devices created by this mkinitramfs generated init
# i.e /dev/live, /dev/live-osimage, /dev/live-overlay and /dev/live-squash
echo "KERNEL==\"$LIVE_BOOTDEV\" SYMLINK+=\"live\"" >> $udevrulefn
echo "KERNEL==\"${SQUASHED_LOOPDEV#/dev/}\" SYMLINK+=\"live-squash\"" >> $udevrulefn
echo "KERNEL==\"${BASE_LOOPDEV#/dev/}\" SYMLINK+=\"live-osimage\"" >> $udevrulefn
echo "KERNEL==\"${OVERLAY_LOOPDEV#/dev/}\" SYMLINK+=\"live-overlay\"" >> $udevrulefn

# Add the device-mapper nodes to real /dev:
cp -af /dev/mapper /dev/root /mnt/lib/udev/devices

mount -n -o ro,remount /mnt

if [ -x /mnt$init ] ; then

    # Leave initramfs and transition to rootfs
    killall udevd

    # Wait for UDEV exit
    sleep 1

    echo "switching root and transfering control to $init"

    echo 0x0100 > /proc/sys/kernel/real-root-dev

    unset ERR

    umount /sys
    umount -l /dev/pts
    umount -l /dev
    umount /proc 2> /dev/null

    echo "${INITRD}:  Transfering control to Real System"
    exec switch_root /mnt $init
else
    echo "---------------------------------------------------------"
    echo "WARNING: Requested $init binary does not exist on rootfs."
    echo "---------------------------------------------------------"
    echo
    echo "Dropping to a shell. Good luck!"
    echo
    exec /bin/sh
fi