Flesh out a simple framework for dependency checking rc.conf enabled

services.  Simple YES/NO style *_enable services are supported.

Reviewed by:	obrien

etc/rc

@@ -71,36 +71,32 @@ elif [ -r /etc/rc.conf ]; then
 	. /etc/rc.conf
 fi
 
-# Deal with dependancies.
-	case ${amd_enable} in
+chkdepend() {
+	svc=$1
+	svc_var=$2
+	dep=$3
+	dep_var=$4
+
+	eval svc_val=\${$svc_var}
+	eval dep_val=\${$dep_var}
+
+	case ${svc_val} in
 	[Yy][Ee][Ss])
-		case ${portmap_enable} in
+		case ${dep_val} in
 		[Yy][Ee][Ss])
-			;;
+		    ;;
 		*)
-			portmap_enable="YES"
-			echo "DEPENDENCY NOTE: portmap will be enabled" \
-			     "to support amd"
-			;;
+		    eval ${dep_var}="YES"
+		    echo "DEPENDENCY NOTE: ${dep} will be enabled" \
+			 "to support ${svc}"
+		    ;;
 		esac
 		;;
 	esac
-	case ${nfs_server_enable} in
-	[Yy][Ee][Ss])
-		if [ -r /etc/exports ]; then
-			case ${portmap_enable} in
-			[Yy][Ee][Ss])
-				;;
-			*)
-				portmap_enable="YES"
-				echo "DEPENDENCY NOTE: portmap will be enabled" \
-				     "to support NFS"
-				;;
-			esac
-		fi
-		;;
-	esac
+}
 
+chkdepend amd amd_enable        portmap portmap_enable
+chkdepend NFS nfs_server_enable portmap portmap_enable
 
 # First pass at entropy recovery so the rebooting /dev/random can reseed.
 #