link: support mtu parameter (like debian)

executor-scripts/linux/link

@@ -1,5 +1,9 @@
 #!/bin/sh
 [ -z "$VERBOSE" ] || set -x
+OPTIONS=""
 case "$PHASE" in
-up|down)	${MOCK} ip link set $PHASE dev $IFACE ;;
+up|down)
+	[ -n "$IF_MTU" ] && OPTIONS="$OPTIONS mtu $IF_MTU"
+	${MOCK} ip link set $PHASE dev $IFACE $OPTIONS
+	;;
 esac

tests/linux/link_test

@@ -3,7 +3,7 @@
 . $(atf_get_srcdir)/../test_env.sh
 EXECUTOR="$(atf_get_srcdir)/../../executor-scripts/linux/link"
 
-tests_init up down
+tests_init up down mtu
 
 up_body() {
 	export IFACE=lo PHASE=up MOCK=echo
@@ -16,3 +16,9 @@ down_body() {
 	atf_check -s exit:0 -o match:'ip link set down dev lo' \
 		${EXECUTOR}
 }
+
+mtu_body() {
+	export IFACE=eth0 PHASE=up MOCK=echo IF_MTU=1492
+	atf_check -s exit:0 -o match:'ip link set up dev eth0 mtu 1492' \
+		${EXECUTOR}
+}