#!/bin/sh

# IP-, NFS- und (D)NBD-Parameter aus der Kernel-Kommandozeile lesen
for opts in ${KCMDLINE} ; do
  case ${KCMDLINE} in
    ip=*)
      # IP-Konfiguration: client-ip:server-ip:gateway:netmask
      IPINFO=${opts#ip=};;
    nfsroot=*)
      # NFS-Server und Pfad
      NFSROOT=${opts#nfsroot=};;
    nbdroot=*)
      # NBD-Konfiguration: server:port
      NBD=nbd # name of kernel module
      NBDOPT=${opts#nbdroot=};;
    dnbdroot=*)
      # DNBD-Konfiguration: server:port
      NBD=dnbd # name of kernel module
      NBDOPT=${opts#dnbdroot=};;
    dcsize=*)
      # RAM-Cache-Größe für DNBD
      DNBDCACHESIZE=${opts#dcsize=};;
  esac
done
RWDIR=/dev/shm

# Root-Filesystem via NBD/DNBD importieren
if [ -n "${NBD}" ] ; then
  nbdhost=${NBDOPT%:*}
  nbdopt=${NBDOPT#*:}
  nbdport=${nbdopt%,*}
  nbdfs=${nbdopt#$nbdport*}
  if [ -z "$nbdfs" ]; then
    RFST=ext2;
  else
    RFST=${nbdfs#*,};
  fi
  echo "Diskless client using ${NBD} on $nbdhost:$nbdport with $RFST"
  modprobe ${RFST}
  case "${NBD}" in
    nbd)
      # Network Block Device des Standard-Kernels
      sleep 2
      nbd-client $nbdhost $nbdport /dev/nbd0
      RDEV=/dev/nbd0;;
    dnbd)
      # DNBD (Distributed Network Block Device)
      if [ -z $nodnbdcache ] ; then  # variable not really used yet
        mkdir /dnbd
        mount -n -o 'size=$dcsize' -t tmpfs tmpfs ${RWDIR}
        cat /dev/zero > ${RWDIR}/cache 2>/dev/null
        clientopt="-c ${RWDIR}/cache"
      fi
      sleep 2
      while ! dnbd-client -b $nbdhost -d /dev/dnbd0 $clientopt ; do
        sleep 1
      done
      RDEV=/dev/dnbd0;;
  esac
  RWRO="ro"
  if [ -n "${COWLOOP}" -a -x /bin/cowdev ] ; then
    modprobe cowloop
    echo "Using Copy-on-Write block device for rw access"
    mount -n -t tmpfs -o size=50% ramfs ${RWDIR}
    mkdir /dev/cow && cp -a /tmp/ctl /dev/cow
    ln -s /dev/cowloop0 /dev/cow/0
    cowdev -a ${RDEV} ${RWDIR}/nbd.cow
    usleep 10
    RWRO="rw"
    RDEV=/dev/cow/0
  fi
  sleep 2
  mount -n -t $RFST -o $RWRO $RDEV /mnt

# Root-Filesystem via NFS importieren
elif [ -n NFS ]
  modprobe nfs
  portmap
  NFSRO=nfs
  mount -t nfs <§§I>[...]<§§I>
fi

# Union-FS aktivieren
echo "Using UnionFS for rw access"
RWDIR=/dev/shm
mkdir -p ${RWDIR}/union ${RWDIR}/uniontmp
mount -n -t tmpfs none ${RWDIR}/uniontmp
mount -n --move /mnt /root
mount -n -t unionfs -o dirs=${RWDIR}/uniontmp=rw:/root=${NFSRO}ro none /mnt
mkdir -p /mnt/uniontmp
mount -n --move ${RWDIR}/uniontmp /mnt/uniontmp
mount -n --move /root /mnt/mnt

# Pivoting nach neuer Art
exec run-init -c dev/console /mnt /sbin/init