[PATCH] Change _find_net_interfaces to prefer ip on linux

[drelo <1127662780@qq.com>]

From linux 5.4, we can reference network interfaces through altnames,
so we show also show altnames in completion.

$ ip link show dev wlp8s0 
4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DORMANT group default qlen 1000
    link/ether xx:xx:xx:xx:xx:xx brd ff:ff:ff:ff:ff:ff
    altname wlp8s0

$ ip link show dev <TAB>
docker0      enp7s0       lo           vetha513db5  wlan0        wlp8s0


---
 Completion/Unix/Type/_find_net_interfaces | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/Completion/Unix/Type/_find_net_interfaces b/Completion/Unix/Type/_find_net_interfaces
index 3f5db6b9a..4076bc125 100644
--- a/Completion/Unix/Type/_find_net_interfaces
+++ b/Completion/Unix/Type/_find_net_interfaces
@@ -22,11 +22,17 @@ case $OSTYPE in
   darwin*|freebsd*|dragonfly*) net_intf_list=( $(ifconfig -l) ) ;;
   irix*) net_intf_list=( ${${${(f)"$(/usr/etc/netstat -i)"}%% *}[2,-1]} ) ;;
   *)
-    # linux's deprecated ifconfig may truncate long interface names
-    net_intf_list=( $(_call_program interfaces "ifconfig -a 2>/dev/null | sed -n 's/^\([^ 	:]*\).*/\1/p'") )
+    if (( $+commands[ip] )); then
+      # if ip is available, we can also show altnames
+      net_intf_list=( $(_call_program interfaces "ip link | sed -ne 's/^[0-9]\+: \([^:@]\+\).*/\1/p;t; s/^[\ ]\+altname \(.\+\)\$/\1/p'") )
+    else
+      # linux's deprecated ifconfig may truncate long interface names
+      net_intf_list=( $(_call_program interfaces "ifconfig -a 2>/dev/null | sed -n 's/^\([^ 	:]*\).*/\1/p'") )
+    fi
+    
     if (( ${#net_intf_list} == 0 )) && [[ -d /proc/sys/net/ipv4/conf ]]; then
       # On linux we used to use the following as the default, without /sys/class/net/*.
-      # However, we now use ifconfig since it finds additional devices such
+      # However, we now use ip or ifconfig since it finds additional devices such
       # as tunnels.  So only do this if that didn't work.
       typeset -gU net_intf_list
       net_intf_list=( /proc/sys/net/ipv4/conf/*~*(all|default)(N:t) /sys/class/net/*(N:t) )
-- 
2.27.0