#!/bin/sh
#
# mkconf -- outputs valid mdadm.conf contents for the local system
#
# Copyright © martin f. krafft <madduck@madduck.net>
# distributed under the terms of the Artistic Licence 2.0
#
# $Id$
#

set -eu

MDADM=/sbin/mdadm
DEBIANCONFIG=/etc/default/mdadm

if [ ! -d /proc/$$ ]; then
  echo E: /proc not available. Exiting... >&2
  exit 2
fi

test -f $DEBIANCONFIG && . $DEBIANCONFIG

generate=0
CONFIG=/etc/mdadm/mdadm.conf
[ "${1:-}" = force-generate ] && rm -f $CONFIG
case "${1:-}" in
  generate|force-generate)
    [ -n "${2:-}" ] && CONFIG=$2
    if [ -e $CONFIG ]; then
      echo "E: ${##*/}: $CONFIG already exists." >&2
      exit 3
    fi
    
    mkdir --parent ${CONFIG%/*}
    exec >$CONFIG
    generate=1
    ;;
esac

cat <<_eof
# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#

_eof

if [ -r /proc/partitions ]; then
  cat <<_eof
# scan all partitions (/proc/partitions) for MD superblocks"
DEVICE partitions

_eof
else
  echo E: cannot read /proc/partitions and thus cannot do my magic. >&2
  exit 1
fi

cat <<_eof
# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes

# automatically tag new arrays as belonging to the local system
HOMEHOST <system>

# instruct the monitoring daemon to send mail alerts to root
MAILADDR root

_eof

if [ ! -r /proc/mdstat ]; then
  echo W: MD subsystem is not loaded, thus I cannot scan for arrays. >&2
else
  echo "# definitions of existing MD arrays"
  $MDADM --examine --scan --config=partitions
  echo
fi

cat <<_eof
# This file was auto-generated on $(date -R)
# by mkconf \$Id$
_eof

if [ $generate -eq 1 ]; then
  mkdir -p /var/lib/mdadm
  md5sum $CONFIG > /var/lib/mdadm/mdadm.conf-generated
fi

exit 0