#!/bin/bash

# Warning: the order is important

# If a directory containing $ROOTDIR is listed here,

# it MUST be listed last. (/var/named contains /var/named/chroot)

ROOTDIR_MOUNT='/etc/localtime /etc/named.root.key /etc/named.conf

/etc/named.rfc1912.zones /etc/rndc.conf /etc/rndc.key /etc/named.iscdlv.key

/etc/crypto-policies/back-ends/bind.config /etc/protocols /etc/services

/etc/named.dnssec.keys /etc/pki/dnssec-keys

/etc/named /usr/lib64/bind /usr/lib/bind /run/named

/var/named'

usage()

{

  echo

  echo 'This script setups chroot environment for BIND'

  echo 'Usage: setup-named-chroot.sh ROOTDIR [on|off]'

}

if ! [ "$#" -eq 2 ]; then

  echo 'Wrong number of arguments'

  usage

  exit 1

fi

ROOTDIR="$1"

# Exit if ROOTDIR doesn't exist

if ! [ -d "$ROOTDIR" ]; then

  echo "Root directory $ROOTDIR doesn't exist"

  usage

  exit 1

fi

mount_chroot_conf()

{

  if [ -n "$ROOTDIR" ]; then

    for all in $ROOTDIR_MOUNT; do

      # Skip nonexistant files

      [ -e "$all" ] || continue

      # If mount source is a file

      if ! [ -d "$all" ]; then

        # mount it only if it is not present in chroot or it is empty

        if ! [ -e "$ROOTDIR$all" ] || [ `stat -c'%s' "$ROOTDIR$all"` -eq 0 ]; then

          touch "$ROOTDIR$all"

          mount --bind "$all" "$ROOTDIR$all"

        fi

      else

        # Mount source is a directory. Mount it only if directory in chroot is

        # empty.

        if [ -e "$all" ] && [ `ls -1A $ROOTDIR$all | wc -l` -eq 0 ]; then

          mount --bind --make-private "$all" "$ROOTDIR$all"

        fi

      fi

    done

  fi

}

umount_chroot_conf()

{

  if [ -n "$ROOTDIR" ]; then

    for all in $ROOTDIR_MOUNT; do

      # Check if file is mount target. Do not use /proc/mounts because detecting

      # of modified mounted files can fail.

      if mount | grep -q '.* on '"$ROOTDIR$all"' .*'; then

        umount "$ROOTDIR$all"

        # Remove temporary created files

        [ -f "$all" ] && rm -f "$ROOTDIR$all"

      fi

    done

  fi

}

case "$2" in

  on)

    mount_chroot_conf

    ;;

  off)

    umount_chroot_conf

    ;;

  *)

    echo 'Second argument has to be "on" or "off"'

    usage

    exit 1

esac

exit 0