#!/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
#
set -eu

ME="${0##*/}"
MDADM=/sbin/mdadm
DEBIANCONFIG=/etc/default/mdadm
CONFIG=/etc/mdadm/mdadm.conf

# initialise config variables in case the environment leaks
MAILADDR= DEVICE= CREATE= HOMEHOST= PROGRAM=

test -r $DEBIANCONFIG && . $DEBIANCONFIG

if [ -n "${MDADM_MAILADDR__:-}" ]; then
  # honour MAILADDR from the environment (from postinst)
  MAILADDR="$MDADM_MAILADDR__"
else
  # preserve existing MAILADDR
  MAILADDR="$(sed -ne 's/^MAILADDR //p' $CONFIG 2>/dev/null)" || :
fi

# save existing values as defaults
if [ -r "$CONFIG" ]; then
  DEVICE="$(sed -ne 's/^DEVICE //p' $CONFIG)"
  CREATE="$(sed -ne 's/^CREATE //p' $CONFIG)"
  HOMEHOST="$(sed -ne 's/^HOMEHOST //p' $CONFIG)"
  PROGRAM="$(sed -ne 's/^PROGRAM //p' $CONFIG)"
fi

generate=0
[ "${1:-}" = force-generate ] && rm -f $CONFIG
case "${1:-}" in
  generate|force-generate)
    [ -n "${2:-}" ] && CONFIG=$2
    # only barf if the config file specifies anything else than MAILADDR
    if egrep -qv '^(MAILADDR.*|#.*|)$' $CONFIG 2>/dev/null; then
      echo "E: $ME: $CONFIG already exists." >&2
      exit 255
    fi
    
    mkdir --parent ${CONFIG%/*}
    exec >$CONFIG
    generate=1
    ;;
esac

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

# by default (built-in), scan all partitions (/proc/partitions) and all
# containers for MD superblocks. alternatively, specify devices to scan, using
# wildcards if desired.
#DEVICE ${DEVICE:-partitions containers}

# auto-create devices with Debian standard permissions
CREATE ${CREATE:-owner=root group=disk mode=0660 auto=yes}

# automatically tag new arrays as belonging to the local system
HOMEHOST ${HOMEHOST:-<system>}

# instruct the monitoring daemon where to send mail alerts
MAILADDR ${MAILADDR:-root}

_eof

if [ -n "${PROGRAM:-}" ]; then
  cat <<-_eof
	# program to run when mdadm monitor detects potentially interesting events
	PROGRAM ${PROGRAM}
	
	_eof
fi

error=0
if [ ! -r /proc/mdstat ]; then
  echo W: $ME: MD subsystem is not loaded, thus I cannot scan for arrays. >&2
  error=1
elif [ ! -r /proc/partitions ]; then
  echo W: $ME: /proc/partitions cannot be read, thus I cannot scan for arrays. >&2
  error=2
else
  echo "# definitions of existing MD arrays"
  if ! $MDADM --examine --scan --config=partitions; then
    error=$(($? + 128))
    echo W: $ME: failed to scan for partitions. >&2
    echo "### WARNING: scan failed."
  else
    echo
  fi
fi

if [ $generate -eq 1 ]; then
  cat <<_eof
# This file was auto-generated on $(date -R)
# by mkconf \$Id$
_eof

  mkdir -p /var/lib/mdadm
  md5sum $CONFIG > /var/lib/mdadm/mdadm.conf-generated
fi

exit $error
