From 760c34c94a0ab21363626a0817757cdfdce53ffe Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Tue, 20 Dec 2011 17:06:50 +0100
Subject: [PATCH] lua: properly handle corner cases in changes The previous
 rework of the change serialization caused some deltas to incorrectly get
 promoted to list appends. Rework the code to explicitely check for an add
 list change type, in all other cases simply overwrite existing fields with
 the current string value instead of coercing existing values into a table and
 append to that. This hopefully sorts out the remaining issues.

---
 lua/uci.c | 45 ++++++++++++++++++++++++---------------------
 1 file changed, 24 insertions(+), 21 deletions(-)

diff --git a/lua/uci.c b/lua/uci.c
index 564948b..0667fc2 100644
--- a/lua/uci.c
+++ b/lua/uci.c
@@ -711,35 +711,38 @@ uci_lua_add_change(lua_State *L, struct uci_element *e)
 	if (name) {
 		lua_getfield(L, -1, name);
 
-		/* there seems to be no value yet */
-		if (lua_isnil(L, -1)) {
-			/* this delta is a list add operation, initialize table */
-			if (h->cmd == UCI_CMD_LIST_ADD) {
+		/* this delta is a list add operation */
+		if (h->cmd == UCI_CMD_LIST_ADD) {
+			/* there seems to be no table yet */
+			if (!lua_istable(L, -1)) {
 				lua_newtable(L);
-				lua_pushstring(L, value);
-				lua_rawseti(L, -2, 1);
-				lua_setfield(L, -3, name);
-			} else {
-				lua_pushstring(L, value);
-				lua_setfield(L, -3, name);
-			}
 
-		/* there is a value already, append */
-		} else {
-			/* a string is on top of the stack, coerce into table */
-			if (lua_isstring(L, -1)) {
-				lua_newtable(L);
-				lua_pushvalue(L, -2);
-				lua_rawseti(L, -2, 1);
+				/* if there is a value on the stack already, add */
+				if (!lua_isnil(L, -2)) {
+					lua_pushvalue(L, -2);
+					lua_rawseti(L, -2, 1);
+					lua_pushstring(L, value);
+					lua_rawseti(L, -2, 2);
+
+				/* this is the first table item */
+				} else {
+					lua_pushstring(L, value);
+					lua_rawseti(L, -2, 1);
+				}
+
 				lua_setfield(L, -3, name);
-			}
 
-			/* a table is on the top of the stack so this is a subsequent,
+			/* a table is on the top of the stack and this is a subsequent,
 			 * list_add, append this value to table */
-			if (lua_istable(L, -1)) {
+			} else {
 				lua_pushstring(L, value);
 				lua_rawseti(L, -2, lua_objlen(L, -2) + 1);
 			}
+
+		/* non-list change, simply set/replace field */
+		} else {
+			lua_pushstring(L, value);
+			lua_setfield(L, -3, name);
 		}
 
 		lua_pop(L, 1);
-- 
2.30.2