#!/bin/ksh93
 
# $Id$
# /usr/share/mdadm/mkconf

set -eu

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

function addSparegroups {
	[[ -z $2 ]] && return
	typeset -n ARRAYS=$1
	typeset -a KV=( ${2//,/ } ) MS
	unset MD2SG ; typeset -A MD2SG
	typeset X LINE 
	(( ! ${#KV[@]} )) && return
	for X in "${KV[@]}" ; do
		[[ -z $X ]] && continue
		MS=( ${X//:/ } )
		if (( ${#MS[@]} != 2 )) || [[ ${MS:0:7} != '/dev/md' ]]; then
			print -u2 "W: ${ME}: Invalid spare-group value '$X' ignored!"
			continue
		fi
		MD2SG["${MS[0]}"]="${MS[1]}"
	done
	(( ! ${#MD2SG[@]} )) && return
	typeset OLDIFS="${IFS}"
	IFS=$'\n'
	MS=( ${ARRAYS} )
	IFS=${OLDIFS}
	integer C=0
	ARRAYS=""
	for LINE in "${MS[@]}" ; do
		ARRAYS+="\n${LINE}"
		[[ "${LINE:0:13}" != 'ARRAY /dev/md' ]] && continue
		X="${LINE:6}"
		X="${X%%+(\s*)}"
		[[ -n ${MD2SG["${X}"]:-} ]] && ARRAYS+="\n   spare-group=${MD2SG[${X}]}"
	done
}

function doMain {
	# initialize config variables in case the environment leaks
	unset CFG ; typeset -A CFG
	typeset KEY VAL TXT
	integer GENERATE=0 FORCE=0 COUNT=0

	if [[ $1 == 'generate' ]]; then
		GENERATE=1
	elif [[ $1 == 'force-generate' ]]; then
		GENERATE=1
		FORCE=1
	fi
	(( GENERATE )) && [[ -n $2 ]] && CONFIG="$2"
	
	# honor MAILADDR from the environment (from postinst)
	[[ -n ${MDADM_MAILADDR__:-} ]] && CFG['mail']="${MDADM_MAILADDR__}"
	
	# save existing values
	if (( ! FORCE )) && [[ -r ${CONFIG} ]]; then
		while read KEY VAL; do
			[[ -z ${KEY} || ${KEY:0:1} == '#' ]] && continue
			(( COUNT++ ))
			[[ ${KEY} =~ ^(DEVICE|CREATE|HOMEHOST|PROGRAM|MAILADDR)$ ]] && \
				CFG["${KEY}"]="${VAL}"
			[[ ${KEY} == 'MAILADDR' ]] && (( COUNT-- ))
		done < "${CONFIG}"
	fi
	if [[ -r ${DEBIANCONFIG} ]]; then
		while read KEY ; do
			[[ ${KEY:0:12} == 'SPAREGROUPS=' ]] && CFG['SG']="${KEY:12}"
		done < "${DEBIANCONFIG}"
	fi
	
	if (( GENERATE )); then
		# only barf if the config file specifies anything else than MAILADDR
		if (( COUNT )); then
			print -u2 "E: ${ME}: ${CONFIG} already exists."
			exit 255
		fi
	
		[[ ! -d "${CONFIG%/*}" ]] && mkdir --parent "${CONFIG%/*}"
	fi
	
	[[ -z ${CFG['DEVICE']:-} ]] && CFG['DEVICE']='partitions containers'
	[[ -z ${CFG['CREATE']:-} ]] && \
		CFG['CREATE']='owner=root group=disk mode=0660 auto=yes'
	[[ -z ${CFG['HOMEHOST']:-} ]] && CFG['HOMEHOST']='<system>'
	[[ -z ${CFG['MAILADDR']:-} ]] && CFG['MAILADDR']='root'
	
		TXT='# 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 '"${CFG['DEVICE']}"'

# auto-create devices with Debian standard permissions
CREATE '"${CFG['CREATE']}"'

# automatically tag new arrays as belonging to the local system
HOMEHOST '"${CFG['HOMEHOST']}"'

# instruct the monitoring daemon where to send mail alerts
MAILADDR '"${CFG['MAILADDR']}"'

'
	
	if [[ -n ${CFG['PROGRAM']:-} ]]; then
	  TXT+='
# program to run when mdadm monitor detects potentially interesting events
PROGRAM '"${CFG['PROGRAM']}"'

'
	fi
	
	COUNT=0
	if [[ ! -r /proc/mdstat ]]; then
		print -u2 "W: ${ME}: MD subsystem is not loaded, thus I cannot scan for arrays."
		COUNT=1
	elif [[ ! -r /proc/partitions ]]; then
		print -u2 "W: ${ME}: /proc/partitions cannot be read, thus I cannot scan for arrays."
		COUNT=2
	else
		TXT+='# definitions of existing MD arrays\n'
		# needed to keep/honor DEVICE settings
		KEY=${ mktemp --tmpdir=/tmp mkconf.XXXXXX; }
		if [[ -z ${KEY} ]]; then
			print -u2 "E: ${ME}: Unable to create tempfile in /tmp/."
			COUNT=3
		else
			print "${TXT}" >>"${KEY}"
			VAL=${ ${MDADM} --examine --scan --config=${KEY} || COUNT=$? ; }
			if (( COUNT )) then
				(( COUNT+=128 ))
				print -u2 "W: ${ME}: failed to scan for partitions."
			else
				if [[ -z ${VAL} ]]; then
					print -u2 "W: ${ME}: No arrays found!"
				else
					addSparegroups VAL "${CFG['SG']:-}"
					TXT+="${VAL}\n"
				fi
				if (( GENERATE )); then
					TXT+="# Auto-generated on ${ uname -n; } on ${ date -R;}\n"
					TXT+="# by ${ME} "'$Id$'
				fi
			fi
			rm -f "${KEY}"
		fi
	fi
	
	# finally write the config
	if (( DRY )); then
		print "${TXT}"
	else
		print "${TXT}" >"${CONFIG}" || COUNT=4
	fi
	
	if (( COUNT )); then
		print "\n${CONFIG}  would look like this:\n"
		print "${TXT}"
	elif (( GENERATE && ! DRY )); then
		KEY='/var/lib/mdadm'
		[[ ! -d ${KEY} ]] && mkdir -p "${KEY}"
		md5sum "${CONFIG}" > "${KEY}/mdadm.conf-generated"
	fi
}
	
function showUsage {
    getopts -a "${ME}" "${ print ${USAGE}; }" OPT --man
}

USAGE='[-?$Id$ ]
[-copyright?Copyright (c) 2014 Jens Elkner. All rights reserved.]
[-license?CDDL 1.0]
[+NAME?'"${ME}"' - create a valid mdadm.conf]
[+DESCRIPTION?This script can be used on \bLinux\b to generate valid \bmdadm\b(8) configuration file (default: \b'"${CONFIG}"'\b). Also \bupdate-initramfs\b(8) invokes this file to create or update the default configuration file unless it already exists and contains at least one \bARRAY\b definition.]
[+?If the debian configuration file \b'"${DEBIANCONFIG}"'\b exists, it gets parsed for a \bSPAREGROUPS=\b\aVALUE\a definition. If found, the generated \bARRAY\b definitions are supplemented with the corresponding \bspare-group\b settings. \aVALUE\a is a comma separated list of \amd_dev\a\b:\b\asparegroup\a, whereby \amd_dev\a is the related \b/dev/md/\b\aN\a node (e.g. /dev/md/1) and \asparegroup\a the name of the spare-group to use for this array (whitespaces are not allowed here). E.g. SPAREGROUPS=/dev/md/2:big,/dev/md/5:big,/dev/md/3=small,/dev/md/4:small]
[+?If \bgenerate\b or \bforce-generate\b is given, a MD5 checksum gets generated for the new file and will be stored in \b/var/lib/mdadm/\b. The difference between both is, that \bforce-generate\b will ignore the current config file copletely and generate it from the scratch using "\bpartitions container\b" as config parameter for \bmdadm\b(8).]
[+?If \afile\a is given, this one would be used instead of the default configuration file.]
[+FILES?]{
	[+'"${CONFIG}"'?The default \bmdadm\b(8) configuration file.]
	[+'"${DEBIANCONFIG}"'?The debian configuration file used to obtain \bSPAREGROUPS\b definitions.]
	[+/usr/share/mdadm/mkconf?The script used by \bupdate-initramfs\b(8) to update the default configuration file.]
}
[+SEE ALSO?\bmdadm.conf\b(5), \bmdadm\b(8).]
[+NOTE?This script ignores all \bmdadm.conf\b(5) keywords from the current configuration file except \bDEVICE\b, \bCREATE\b, \bHOMEHOST\b, \bPROGRAM\b and \bMAILADDR\b, i.e. other settings will be lost!]
[+?If the user executing this script has no read privilege for the corresponding raw block devices, \bmdadm\b(8) cannot read the meta information from its superblock and thus will possibly not find all available arrays!]
[h:help?Print this help and exit.]
[F:functions?Print a list of all functions of this script.]
[T:trace]:[functionList?A comma separated list of functions of this script to trace (convinience for troubleshooting).]
[n:dry?Print the generated configuration to stdout, only.]
\n\n[{\bgenerate\b|\bforce-generate\b} [\afile\a]]
'

integer DRY=0 IDX
while getopts -a "${ME}" "${ print ${USAGE}; }" OPT ; do
	case ${OPT} in
		h) showUsage ; exit 0 ;;
		F) typeset +f && exit 0 ;;
		T) typeset -ft ${OPTARG//,/ } ;;
		n) DRY=1 ;;
	esac
done
(( IDX=OPTIND-1 ))
shift $IDX

doMain "$@"