From 8c36d8b131f2172ce8caaa20057af4d35b72c781 Mon Sep 17 00:00:00 2001
From: William Wilgus <wilgus.william@gmail.com>
Date: Fri, 13 Aug 2021 22:36:52 -0400
Subject: [PATCH] lua Fix a few potential bugs

Change-Id: I0293371c58f1ca2d148b3b1e1f780cf76f312ef9
---
 apps/plugins/lua/lauxlib.c  | 6 ++++--
 apps/plugins/lua/lmathlib.c | 5 ++++-
 apps/plugins/lua/lparser.c  | 2 ++
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/apps/plugins/lua/lauxlib.c b/apps/plugins/lua/lauxlib.c
index b8332427f0..9a5939aff9 100644
--- a/apps/plugins/lua/lauxlib.c
+++ b/apps/plugins/lua/lauxlib.c
@@ -803,8 +803,10 @@ static int panic (lua_State *L) {
 
 LUALIB_API lua_State *luaL_newstate (void) {
   lua_State *L = lua_newstate(l_alloc, NULL);
-  lua_setallocf(L, l_alloc, L); /* allocator needs lua_State. */
-  if (L) lua_atpanic(L, &panic);
+  if (L){
+    lua_setallocf(L, l_alloc, L); /* allocator needs lua_State. */
+    lua_atpanic(L, &panic);
+  }
   return L;
 }
 
diff --git a/apps/plugins/lua/lmathlib.c b/apps/plugins/lua/lmathlib.c
index 56c79afced..839d2014ad 100644
--- a/apps/plugins/lua/lmathlib.c
+++ b/apps/plugins/lua/lmathlib.c
@@ -96,7 +96,10 @@ static int math_floor (lua_State *L) {
 
 static int math_fmod (lua_State *L) {
   /* Was: lua_pushnumber(L, fmod(luaL_checknumber(L, 1), luaL_checknumber(L, 2))); */
-  lua_pushnumber(L, luaL_checknumber(L, 1) % luaL_checknumber(L, 2));
+  lua_Number n = luaL_checknumber(L, 1);
+  lua_Number d = luaL_checknumber(L, 2);
+  luaL_argcheck(L, d != 0, 2, "division by zero");
+  lua_pushnumber(L, n % d);
   return 1;
 }
 
diff --git a/apps/plugins/lua/lparser.c b/apps/plugins/lua/lparser.c
index 23d3972036..06c62cedde 100644
--- a/apps/plugins/lua/lparser.c
+++ b/apps/plugins/lua/lparser.c
@@ -359,6 +359,8 @@ static void open_func (LexState *ls, FuncState *fs) {
 
 
 static void close_func (LexState *ls) {
+  if (!ls || !ls->fs || !ls->fs->f)
+    return;
   lua_State *L = ls->L;
   FuncState *fs = ls->fs;
   Proto *f = fs->f;