rc.inet1*: Simplify virtif_* code, add note to example config

There is a built-in way of counting the number of elements in an array:
${#arrayname[@]}. Use this, and the fact that "for i in $(seq 0 -1)" will
not evaluate body of the loop even once, to simplify code and get rid of
virtif_determine().

While at it, add a note to rc.inet1.conf mentioning the necessity of
keeping array indexes monotonically increasing (from 0), otherwise the
code will fail (so would the original code).

Signed-off-by: Robby Workman <rworkman@slackware.com>

1 files changed, 8 insertions, 15 deletions

diff --git a/rc.inet1 b/rc.inet1
index 6b88d2a..64dbb05 100644
--- a/rc.inet1
+++ b/rc.inet1
@@ -73,27 +73,20 @@ lo_down() {
 # INTERFACE FUNCTIONS #
 #######################
 
-# Function to determine if virtual interfaces are defined
-virtif_determine() {
-  if [ -n "${VIRTIFNAME}" ]; then
-    virtifcount=$(($(echo ${VIRTIFNAME[@]} | wc -w) - 1))
-  else
-    return 1
-  fi
-}
-
 # Function to create virtual interfaces
 virtif_create() {
-  # argument is 'i' - the position of this interface in the IFNAME array.
-  for i in $(seq 0 ${virtifcount}); do
+  # argument is 'i' - the position of this interface in the VIRTIFNAME array.
+  # this loop goes from i=0 to i=number_of_configured_virtual_interfaces_minus_one
+  # which means it doesn't do anything if there are none.
+  for i in $(seq 0 $((${#VIRTIFNAME[@]} - 1))); do
     /sbin/ip tuntap add dev ${VIRTIFNAME[$i]} mode ${VIRTIFTYPE[$i]} user ${VIRTIFUSER[$i]} group ${VIRTIFGROUP[$i]}
   done
 }
 
 # Function to destory virtual interfaces
 virtif_destroy() {
-  # argument is 'i' - the position of this interface in the IFNAME array.
-  for i in $(seq 0 ${virtifcount}); do
+  # argument is 'i' - the position of this interface in the VIRTIFNAME array.
+  for i in $(seq 0 $((${#VIRTIFNAME[@]} - 1))); do
     /sbin/ip tuntap del dev ${VIRTIFNAME[$i]} mode ${VIRTIFTYPE[$i]}
   done
 }
@@ -296,7 +289,7 @@ gateway_down() {
 # Function to start the network:
 start() {
   lo_up
-  virtif_determine && virtif_create
+  virtif_create
   for i in "${IFNAME[@]}" ; do
     if_up $i
   done
@@ -309,7 +302,7 @@ stop() {
   for i in "${IFNAME[@]}" ; do
     if_down $i
   done
-  virtif_determine && virtif_destroy
+  virtif_destroy
   lo_down
 }