From a942a8f6600b2f2457d4ae5a0493dee97203a7c7 Mon Sep 17 00:00:00 2001
From: helixhorned <helixhorned@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Fri, 19 Jul 2013 12:49:07 +0000
Subject: [PATCH] Lunatic: protect global environment.

git-svn-id: https://svn.eduke32.com/eduke32@3967 1a8010ca-5511-0410-912e-c29ae57300e0
---
 polymer/eduke32/source/lunatic/defs.ilua | 15 +++++++++++----
 polymer/eduke32/source/lunatic/test.elua | 12 +++++++++++-
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/polymer/eduke32/source/lunatic/defs.ilua b/polymer/eduke32/source/lunatic/defs.ilua
index f86c13090..f746d09eb 100644
--- a/polymer/eduke32/source/lunatic/defs.ilua
+++ b/polymer/eduke32/source/lunatic/defs.ilua
@@ -2425,9 +2425,6 @@ end
 -- We need this at the end because we were previously doing just that!
 setmetatable(
     G_, {
-        __newindex = function (_1, n, _2)
-            error("attempt to write to undeclared variable '"..n.."'", 2)
-        end,
         __index = function (_, n)
             error("attempt to read undeclared variable '"..n.."'", 2)
         end,
@@ -2435,11 +2432,21 @@ setmetatable(
         __metatable = true,
         })
 
+local global_mt = {
+    __index = G_,
+
+    __newindex = function()
+        error("attempt to write into the global environment")
+    end,
+
+    __metatable = true,
+}
+
 -- Change the environment of the running Lua thread so that everything
 -- what we've set up will be available when this chunk is left.
 -- In particular, we need the globals defined after setting this chunk's
 -- environment earlier.
-setfenv(0, _G)
+setfenv(0, setmetatable({}, global_mt))
 
 do
     -- If we're running from a savegame restoration, create the restoration
diff --git a/polymer/eduke32/source/lunatic/test.elua b/polymer/eduke32/source/lunatic/test.elua
index c22409b81..1b54f08e9 100644
--- a/polymer/eduke32/source/lunatic/test.elua
+++ b/polymer/eduke32/source/lunatic/test.elua
@@ -1,6 +1,7 @@
 -- test script for ELua/Lunatic Interpreter
 
 -- error=nil -- must not affect "require"
+local require = require
 local string = require("string")
 local bit = require("bit")
 local math = require("math")
@@ -8,6 +9,15 @@ local math = require("math")
 local pcall = pcall
 local DBG_ = require("_LUNATIC_DBG")
 
+local gv, sector, wall, sprite, spriteext = gv, sector, wall, sprite, spriteext
+local actor, player, projectile = actor, player, projectile
+local gameevent, gameactor = gameevent, gameactor
+
+local spritesofsect = spritesofsect
+local hitscan = hitscan
+
+local assert, error, print, tostring = assert, error, print, tostring
+
 print('---=== ELua Test script ===---')
 
 local function printf(fmt, ...)
@@ -98,7 +108,7 @@ gameevent
 
 local unsafe = pcall(function() string.UNSAFE=true; end)
 
---tostring = nil  -- REMEMBER
+checkfail("tostring = nil", "attempt to write into the global environment")
 --DBG_.printkv('_G in test.elua', _G)
 
 -- direct gv array access forbidden