Add a script to automatically attach gbde devices found in fstab

(or rc.conf) at boot time, and detach them when shutting down.  Not
added to the Makefile to give the rcng gurus an opportunity to improve
it.

etc/rc.d/gbde

@@ -0,0 +1,92 @@
+#!/bin/sh
+#
+# This file, originally written by Garrett A. Wollman, is in the public
+# domain.
+#
+# $FreeBSD$
+#
+
+# PROVIDE: disks
+# KEYWORD: FreeBSD
+
+. /etc/rc.subr
+
+name="gbde"
+start_precmd="find_gbde_devices start"
+stop_precmd="find_gbde_devices stop"
+start_cmd="gbde_start"
+stop_cmd="gbde_stop"
+
+find_gbde_devices()
+{
+	case "${gbde_devices-auto}" in
+	[Aa][Uu][Tt][Oo])
+		gbde_devices="";;
+	*)
+		return 0;;
+	esac
+
+	case "$1" in
+	start)	fstab="/etc/fstab";;
+	stop)	fstab=$(mktemp /tmp/mtab.XXXXXX)
+		mount -p >${fstab}
+	esac
+
+	#
+	# We can't use "mount -p | while ..." because when a shell loop
+	# is the target of a pipe it executes in a subshell, and so can't
+	# modify variables in the script.
+	#
+	while read device mountpt type options dump pass; do
+		case "$device" in
+		*.bde)
+			# Ignore swap devices
+			case "$type" in
+			swap)
+				continue;;
+			esac
+
+			case "$options" in
+			*noauto*)
+				if checkyesno gbde_autoattach_all; then
+					gbde_devices="${gbde_devices} ${device}"
+				fi
+				;;
+			*)
+				gbde_devices="${gbde_devices} ${device}"
+				;;
+			esac
+			;;
+		esac
+	done <${fstab}
+
+	case "$1" in
+	stop)	rm -f ${fstab};;
+	esac
+
+	return 0
+}
+
+gbde_start()
+{
+	for device in $gbde_devices; do
+		parentdev=${device%.bde}
+		parent=${parentdev#/dev/}
+		eval "lock=\${gbde_lock_${parent}-\"/etc/${parent}.lock\"}"
+		if [ -e $lock ]; then
+			echo "Configuring Disk Encryption for ${device}."
+			gbde attach ${parentdev} -l ${lock}
+		fi
+	done
+}
+
+gbde_stop()
+{
+	for device in $gbde_devices; do
+		umount ${device}
+		gbde detach ${device%.bde}
+	done
+}
+
+load_rc_config $name
+run_rc_command "$1"