From cbe49cb9a4d25df2cdcd1fb5d6989cdc22a173c5 Mon Sep 17 00:00:00 2001
From: lemoer <git@irrelefant.net>
Date: Thu, 12 May 2022 22:56:16 +0200
Subject: [PATCH] gluon-core: allow subindexing sysconfig references for
 interface roles

This allows to specify something like "/lan[1]" as interface role:

	root@platzhalter-525400123457:/# cat /lib/gluon/core/sysconfig/lan_ifname
	eth0 eth2

	root@platzhalter-525400123457:/# cat /etc/config/gluon
	...
	config interface 'iface_lan_1'
		option name '/lan[1]'    # this references eth2
		list role 'client'
	...
---
 .../gluon-core/luasrc/usr/lib/lua/gluon/util.lua  | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/package/gluon-core/luasrc/usr/lib/lua/gluon/util.lua b/package/gluon-core/luasrc/usr/lib/lua/gluon/util.lua
index 31ce6864..ae29b8a8 100644
--- a/package/gluon-core/luasrc/usr/lib/lua/gluon/util.lua
+++ b/package/gluon-core/luasrc/usr/lib/lua/gluon/util.lua
@@ -147,13 +147,26 @@ function M.get_role_interfaces(uci, role, exclusive)
 	local ret = {}
 
 	local function add(name)
+		local subindex = nil
+
 		-- Interface names with a / prefix refer to sysconfig interfaces
 		-- (lan_ifname/wan_ifname/single_ifname)
 		if string.sub(name, 1, 1) == '/' then
+			subindex = tonumber(string.match(name, "%[(%d+)%]"))
+			if subindex then
+				-- handle something like "/lan[10]":
+				name = string.gsub(name, "%[%d+%]", "")
+			end
+
 			name = sysconfig[string.sub(name, 2) .. '_ifname'] or ''
 		end
+		local i = 0
 		for iface in string.gmatch(name, '%S+') do
-			M.add_to_set(ret, iface)
+			if not subindex or subindex == i then
+				M.add_to_set(ret, iface)
+			end
+
+			i = i + 1
 		end
 	end