Make the default start, stop and status functions overridable

This will make it possible to add support for supervision suites such as
runit and s6.

sh/start-stop-daemon.sh

@@ -0,0 +1,71 @@
+# Default start / stop / status functions
+# Copyright (c) 2007-2009 Roy Marples <roy@marples.name>
+# Released under the 2-clause BSD license.
+
+start()
+{
+	[ -n "$command" ] || return 0
+
+	local _background=
+	ebegin "Starting ${name:-$RC_SVCNAME}"
+	if yesno "${command_background}"; then
+		if [ -z "${pidfile}" ]; then
+			eend 1 "command_background option used but no pidfile specified"
+			return 1
+		fi
+		if [ -n "${command_args_background}" ]; then
+			eend 1 "command_background used with command_args_background"
+			return 1
+		fi
+		_background="--background --make-pidfile"
+	fi
+	if yesno "$start_inactive"; then
+		local _inactive=false
+		service_inactive && _inactive=true
+		mark_service_inactive
+	fi
+	eval start-stop-daemon --start \
+		--exec $command \
+		${procname:+--name} $procname \
+		${pidfile:+--pidfile} $pidfile \
+		${command_user+--user} $command_user \
+		$_background $start_stop_daemon_args \
+		-- $command_args $command_args_background
+	if eend $? "Failed to start $RC_SVCNAME"; then
+		service_set_value "command" "${command}"
+		[ -n "${pidfile}" ] && service_set_value "pidfile" "${pidfile}"
+		[ -n "${procname}" ] && service_set_value "procname" "${procname}"
+		return 0
+	fi
+	if yesno "$start_inactive"; then
+		if ! $_inactive; then
+			mark_service_stopped
+		fi
+	fi
+	return 1
+}
+
+stop()
+{
+	local startcommand="$(service_get_value "command")"
+	local startpidfile="$(service_get_value "pidfile")"
+	local startprocname="$(service_get_value "procname")"
+	command="${startcommand:-$command}"
+	pidfile="${startpidfile:-$pidfile}"
+	procname="${startprocname:-$procname}"
+	[ -n "$command" -o -n "$procname" -o -n "$pidfile" ] || return 0
+	ebegin "Stopping ${name:-$RC_SVCNAME}"
+	start-stop-daemon --stop \
+		${retry:+--retry} $retry \
+		${command:+--exec} $command \
+		${procname:+--name} $procname \
+		${pidfile:+--pidfile} $pidfile \
+		${stopsig:+--signal} $stopsig
+
+	eend $? "Failed to stop $RC_SVCNAME"
+}
+
+status()
+{
+	_status
+}