#!/sbin/openrc-run
# Copyright 1999-2016 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

depend() {
	# As of .67-r1, we call ALL lvm start/stop scripts with --sysinit, that
	# means dmeventd is NOT notified, as it cannot be safely running
	before dmeventd checkfs fsck
	after modules
}

dm_in_proc() {
	local retval=0
	for x in devices misc ; do
		grep -qs 'device-mapper' /proc/${x}
		retval=$((${retval} + $?))
	done
	return ${retval}
}

# char **build_dmsetup_command(volume)
#
# Returns complete dmsetup command given single volume name
build_dmsetup_command() {
	local count dmsetup_cmd
	
	# Number of lines mentioning volume name
	count=$(grep -v -e '^[[:space:]]*\(#\|$\)' /etc/dmtab | grep -c ${1})
	
	# If there's just one line:
	if [ ${count} -eq 1 ] ; then
		echo "echo $(grep -v -e '^[[:space:]]*\(#\|$\)' /etc/dmtab | \
			  grep ${1} | awk '{$1=""; print $0}') | /sbin/dmsetup create ${1}"
			  
	# For all cases with more lines:
	elif [ ${count} -gt 1 ] ; then
		for c in $( seq 1 ${count} ) ; do
			if [ ${c} -eq 1 ] ; then
				# Heavy escaping in awk-statement because we cannot use apostrophes
				dmsetup_cmd="echo -e $(grep -v -e '^[[:space:]]*\(#\|$\)' /etc/dmtab | \
							 grep ${1} | awk NR==${c}\ \{\$1=\"\"\;\ print\ \$0\})"
			else
				# Append starting with newline
				dmsetup_cmd="${dmsetup_cmd}\\\\n \
							 $(grep -v -e '^[[:space:]]*\(#\|$\)' /etc/dmtab | \
							 grep ${1} | awk NR==${c}\ \{\$1=\"\"\;\ print\ \$0\})"
			fi
		done
		echo "${dmsetup_cmd} | /sbin/dmsetup create ${1}"
	fi

	return 0
}

# char **get_new_dm_volumes(void)
#
#   Return unique volumes from /etc/dmtab
get_new_dm_volumes() {
	local volume

	# Filter comments and blank lines
	grep -v -e '^[[:space:]]*\(#\|$\)' /etc/dmtab | \
	awk '{ print $1 }' | \
	uniq | \
	while read volume ; do
		# If it exists, skip it
		dmvolume_exists "${volume%:}" && continue

		echo "${volume%:}"
	done

	return 0
}

# int dmvolume_exists(volume)
#
#   Return true if volume exists in DM table
dmvolume_exists() {
	local x line volume=$1

	[ -z "${volume}" ] && return 1

	/sbin/dmsetup ls 2>/dev/null | \
	while read line ; do
		for x in ${line} ; do
			# the following conditonal return only breaks out
			# of the while loop, as it is running in a pipe.
			[ "${x}" = "${volume}" ] && return 1
			# We only want to check the volume name
			break
		done
	done

	# if 1 was returned from the above loop, then indicate that
	# volume exists
	[ $? = 1 ] && return 0

	# otherwise the loop exited normally and the volume does not
	# exist
	return 1
}

# int is_empty_dm_volume(volume)
#
#   Return true if the volume exists in DM table, but is empty/non-valid
is_empty_dm_volume() {
	local table volume=$1

	set -- $(/sbin/dmsetup table 2>/dev/null | grep -e "^${volume}:")
	[ "${volume}" = "$1" -a -z "$2" ]
}


start() {
	if [ -e /proc/modules ] && ! dm_in_proc ; then
		modprobe dm-mod 2>/dev/null
	fi
	# Ensure the dirs exist for locking and running
	checkpath -q -d -m 0700 -o root:root /run/lvm /run/lock/lvm

	local x volume
	
	if [ -x /sbin/dmsetup -a -c /dev/mapper/control -a -f /etc/dmtab ] ; then
		[ -n "$(get_new_dm_volumes)" ] && \
			einfo " Setting up device-mapper volumes:"
		
		get_new_dm_volumes | \
		while read x ; do
			[ -n "${x}" ] || continue
			
			volume="${x##* }"
			
			ebegin "  Creating volume: ${volume}"
			if ! eval $(build_dmsetup_command ${volume}) >/dev/null 2>/dev/null ; then
				eend 1 "  Error creating volume: ${volume}"
				# dmsetup still adds an empty volume in some cases,
				#  so lets remove it
				is_empty_dm_volume "${volume}" && \
					/sbin/dmsetup remove "${volume}" 2>/dev/null
			else
				eend 0
			fi
		done
	fi
}