revise installation of e/n/i file

functions

@@ -15,18 +15,22 @@ config() {
     eval echo "$1=\$$1"
 }
 
-# Unless the subhost already has a private /etc/network/interfaces,
-# install an "empty" one
+# Install a default $1/etc/network/interfaces on the subhost root $1
 setup_networking() {
-    [ -r $UPPER/etc/network/interfaces ] && return 0
-    [ "$UPPER/etc/network" = "/etc/network" ] && exit 1
-    mkdir -p $UPPER/etc/network
-    cat <<EOF > $UPPER/etc/network/interfaces
+    [ -r $1/etc/network/interfaces ] && return 0
+    mkdir -p $1/etc/network
+    cat <<EOF >> $1/etc/network/interfaces
 # Generated for $NAME subhost
 auto lo
 iface lo inet loopback
 EOF
-    return 1
+    for IF in $(ip netns exec $NAME ip link show | grep "^eth") ; do
+	cat <<EOF >> $1/etc/network/interfaces
+
+auto eth$i
+iface eth$i inet manual
+EOF
+    done
 }
 
 # Setup the network namespace for the given $CABLES
@@ -36,19 +40,12 @@ setup_veth_cables() {
     NETNS="$1"
     shift 1
     i=0
-    ADD=false
-    setup_networking || ADD=true
     for C in "$@" ; do
 	IF=$NETNS$i
 	MAC="${C#*=}"
 	[ -z "$MAC" ] || MAC="address $MAC"
 	ip link add $IF type veth peer name eth$i $MAC netns $NETNS
 	ip link set $IF up
-	$ADD && cat <<EOF >> $UPPER/etc/network/interfaces
-
-auto eth$i
-iface eth$i inet manual
-EOF
 	BR="${C%=*}"
 	if [ -z "$BR" ] ; then
 	    ip link set $IF
@@ -118,10 +115,11 @@ setup_overlay() {
 	mkdir "$UPPER/dev/pts"
 	chmod 1777 "$UPPER/dev/shm"
 
+	# all good so far ; now avoid using the host's networking setup
+	setup_networking "$UPPER"
+
 	OLY="-olowerdir=$3,upperdir=$UPPER,workdir=$5"
-	if mount -t overlay "$OLY" $1 $2 ; then
-	    : # all good
-	else
+	if ! mount -t overlay "$OLY" $1 $2 ; then
 	    umount -R "$UPPER/dev"
 	    umount "$UPPER/run"
 	    die "Cannot set up the overlay mount $2"

overlay-boot

@@ -44,10 +44,11 @@ config CABLES ""
 config START "networking ssh"
 config SUBSHELL /bin/sh
 
-# Setup virtual cabling and subhost's /etc/network/interfaces
+# Setup virtual cabling
 setup_veth_cables $NAME $CABLES
 
 # Set up the mount for this subhost, including a new tmpfs on its /run
+# and a default $UPPER/etc/network/interfaces if needed
 echo setup_overlay "$NAME" "$LIVE" "$LOWER" "$UPPER" "$WORK"
 setup_overlay "$NAME" "$LIVE" "$LOWER" "$UPPER" "$WORK"