From 91b7a10bd0ed3f78781597a5786d98728d1cdd96 Mon Sep 17 00:00:00 2001
From: helixhorned <helixhorned@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Fri, 13 Jul 2012 18:20:38 +0000
Subject: [PATCH] Lunatic: overridden 'require', currently for base modules
 only.

git-svn-id: https://svn.eduke32.com/eduke32@2828 1a8010ca-5511-0410-912e-c29ae57300e0
---
 polymer/eduke32/source/lunatic/defs.ilua | 47 +++++++++++++++++++++---
 polymer/eduke32/source/lunatic/test.elua | 13 +++++--
 2 files changed, 51 insertions(+), 9 deletions(-)

diff --git a/polymer/eduke32/source/lunatic/defs.ilua b/polymer/eduke32/source/lunatic/defs.ilua
index 819ea64d2..fda38bb07 100644
--- a/polymer/eduke32/source/lunatic/defs.ilua
+++ b/polymer/eduke32/source/lunatic/defs.ilua
@@ -502,6 +502,42 @@ end
 
 ---=== Set up restricted global environment ===---
 
+-- These are for this file...
+local string = string
+local table = table
+
+local allowed_modules = {
+    coroutine=coroutine, bit=bit, table=table, math=math, string=string,
+}
+
+for modname, themodule in pairs(allowed_modules) do
+    local mt = {
+        __index = themodule,
+        __newindex = function(tab,idx,val)
+            error("modifying base module table forbidden")
+        end,
+        __metatable = true,
+    }
+
+    allowed_modules[modname] = setmetatable({}, mt)
+end
+
+-- The "require" function accessible to Lunatic code.
+-- Base modules in allowed_modules are wrapped so that they cannot be
+-- modified, (TODO:) user modules are searched in the EDuke32 search
+-- path.  Also, our require never messes with the global environment,
+-- it only returns the module.
+local function our_require(modname)
+    local themodule = allowed_modules[modname]
+
+    if (themodule==nil) then
+        error("NOT IMPLEMENTED")
+        -- need to search user modules here
+    end
+
+    return themodule
+end
+
 -- _G tweaks -- pull in only 'safe' stuff
 local G_ = {}  -- our soon-to-be global environment
 
@@ -510,7 +546,8 @@ local G_ = {}  -- our soon-to-be global environment
 -- this table, since user code could later do pairs=nil.
 local oG = _G
 
-G_.coroutine = coroutine
+G_.require = our_require
+---G_.coroutine = coroutine
 G_.assert = assert
 G_.tostring = tostring
 G_.tonumber = tonumber
@@ -525,7 +562,7 @@ G_.pcall = pcall
 --require
 --rawset
 --jit
-G_.bit = bit
+---G_.bit = bit
 --package
 G_.error = error
 --debug
@@ -534,17 +571,17 @@ G_.error = error
 --load
 G_.unpack = unpack
 G_.pairs = pairs
-G_.table = table
+---G_.table = table
 G_._VERSION = _VERSION
 --newproxy --NOT STD?
 --collectgarbage
 --dofile
 G_.next = next
-G_.math = math
+---G_.math = math
 --loadstring
 --_G
 G_.select = select
-G_.string = string
+---G_.string = string
 G_.type = type
 --getmetatable
 --getfenv
diff --git a/polymer/eduke32/source/lunatic/test.elua b/polymer/eduke32/source/lunatic/test.elua
index dc4194c33..e66a1480b 100644
--- a/polymer/eduke32/source/lunatic/test.elua
+++ b/polymer/eduke32/source/lunatic/test.elua
@@ -2,6 +2,11 @@
 
 --do return end
 
+-- error=nil -- must not affect "require"
+local string = require("string")
+local bit = require("bit")
+local math = require("math")
+
 print('---=== ELua Test script ===---')
 
 local function printf(fmt, ...)
@@ -50,8 +55,6 @@ for i = 0, gv.numsectors/2 do
     sector[i].ceilingpal = 2;
 end
 
-checkfail('gv.sprite[0].yrepeat = 100')  -- direct gv array access forbidden
-
 local vol, lev
 vol, lev = TEMP_getvollev()
 print('volume='..vol..', level='..lev)
@@ -92,6 +95,7 @@ end
 --tostring = nil  -- REMEMBER
 --DBG_.printkv('_G in test.elua', _G)
 
+checkfail('gv.sprite[0].yrepeat = 100')  -- direct gv array access forbidden
 checkfail('local i = sprite["qwe"]')  -- indexing struct array with non-numeric type
 checkfail('print(sprite[100000].ceilingpal)')  -- oob read access
 checkfail('print(gv.sprite[0])')  -- NOTE: gv.sprite doesn't fail, but we can't use it
@@ -108,8 +112,9 @@ checkfail("require('os')")  -- 'require' has been thrown away to be replaced by
                             -- something more restricted later
 checkfail("new_global = 345")  -- we should declare globals
 checkfail('gv.CEILING = 3')  -- can't redefine constants in 'gv'
-checkfail('string.dump(gameevent)')  -- string.dump is unavailable
-
+checkfail('local s=require[[string]]; local tmp=s.dump(gameevent)')  -- string.dump is unavailable
+checkfail('local s=require[[string]]; s.format=nil')  -- disallow changing base module tables
+print('')
 -- This is problematic, even though pretty much every access will yield a
 -- "missing declaration" error.
 -- See http://luajit.org/ext_ffi_api.html#ffi_C about what stuff ffi.C contains.