chroot script for chromeos chrooting

#!/bin/bash

unset ISMOUNTED
test -z "$ASUSER" && ASUSER="chronos"
if test "$1" = "-u"
then
  shift
  ASUSER="$1"
  shift
fi

if test -z "$2" -o -z "$1"
then
  echo "Usage:
  $(basename "$0") chrootdir program <options>
    or
  $(basename "$0") -u user chrootdir program <options>
"
  exit 1
fi

CHROOTDIR="`cd \"$1\" && pwd`"
PROGRAM="$2"

shift
shift

if ! test -d "$CHROOTDIR/proc"
then
  echo "Directory does not exists"; exit 1
fi

function unmnt()
{
  FOUND=1
  COUNT=1
  while test -n "$FOUND" -a $COUNT -lt 100
  do
    unset FOUND
    COUNT=$[$COUNT+1]
    for P in /proc/*/root
    do
      L=$(readlink $P)
      if test -n "$L"
      then
        if test "$L" = "$CHROOTDIR"
        then
          kill -9 "$(echo "$P" | cut -d '/' -f 3)"
          FOUND=1
          ISMOUNTED=1
        fi
      fi
    done
  done
  if test "$ISMOUNTED"
  then
     echo "Unmounting bindings..."
     umount -l "$CHROOTDIR/home" &>/dev/null
     umount -l "$CHROOTDIR/tmp" &>/dev/null
     umount -l "$CHROOTDIR/dev" &>/dev/null
     umount -l "$CHROOTDIR/sys" &>/dev/null
     umount -l "$CHROOTDIR/media" &>/dev/null
     umount -l "$CHROOTDIR/proc" &>/dev/null
  fi
}

if test "$PROGRAM" = "unmount" -o "$PROGRAM" = "umount" -o "$PROGRAM" = "kill"
then
  test -n "$(cat /proc/mounts | grep " $CHROOTDIR/proc ")" && ISMOUNTED=1
  unmnt
  exit
fi

if test -z "$(cat /proc/mounts | grep " $CHROOTDIR/proc ")"
then
  echo "Creating bind mounts.."
  mount -o rbind /home "$CHROOTDIR/home"
  mount -o rbind /tmp "$CHROOTDIR/tmp"
  mount -o rbind /dev "$CHROOTDIR/dev"
  mount -o rbind /sys "$CHROOTDIR/sys"
  mount -o rbind /media "$CHROOTDIR/media"
  mount -o rbind /proc "$CHROOTDIR/proc"
  ISMOUNTED=1

  if test -z "$(cat /proc/mounts | grep " $CHROOTDIR/proc ")"
  then
    echo "Failed mounting"
    unmnt
    exit 1
  fi
fi

"$CHROOTDIR/chrooted/prepare.sh" "$CHROOTDIR"
chroot "$CHROOTDIR" /chrooted/start.sh "$ASUSER" "$PROGRAM" "$@"
retval=$!

exit $retval