Lunatic: protect user modules from tampering, too.

git-svn-id: https://svn.eduke32.com/eduke32@2840 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/source/lunatic/defs.ilua

@@ -528,6 +528,7 @@ for modname, themodule in pairs(allowed_modules) do
         __metatable = true,
     }
 
+    -- Comment out to make base modules not protected:
     allowed_modules[modname] = setmetatable({}, mt)
 end
 
@@ -611,10 +612,27 @@ local function our_require(modname)
         if (type(modtab) ~= "table") then
             errorf(ERRLEV-1, "Didn't load module \"%s\": expected table as return value", modname)
         end
+
         package_loaded[modname] = modtab
+    else
+        modtab = package_loaded[modname]
+
+        if (type(modtab) ~= "table") then
+            errorf(ERRLEV-1, "Didn't load module \"%s\": expected module() to be called", modname)
+        end
     end
 
-    return package_loaded[modname]
+    -- Protect module table...
+    local mt = {
+        __index = modtab,
+        __newindex = function(tab,idx,val)
+            error("modifying module table forbidden", 2)
+        end,
+    }
+    -- ..here:
+    setmetatable(modtab, mt)
+
+    return modtab
 end
 
 

polymer/eduke32/source/lunatic/test.elua

@@ -96,6 +96,8 @@ if (vol==1 and lev==8) then
     end
 end
 
+local unsafe = pcall(function() string.UNSAFE=true; end)
+
 --]]
 --tostring = nil  -- REMEMBER
 --DBG_.printkv('_G in test.elua', _G)
@@ -151,8 +153,12 @@ checkfail('gv.CEILING = 3', "cannot create new or write into existing fields of
 checkfail('local s=require[[string]]; local tmp=s.dump(gameevent)',
           "attempt to call field 'dump' (a nil value)")
 
--- disallow changing base module tables
-checkfail('local s=require[[string]]; s.format=nil', "modifying base module table forbidden")
+if (not unsafe) then
+    -- changing base module tables is disallowed
+    checkfail('local s=require[[string]]; s.format=nil', "modifying base module table forbidden")
+else
+    print('WARNING: RUNNING WITH UNPROTECTED BASE MODULES')
+end
 
 print('')
 -- This is problematic, even though pretty much every access will yield a
@@ -173,6 +179,8 @@ checkfail('local spr = sprite[0]; local x=spr+1',
 
 checkfail('gameactor(1680, 0)', "bad argument #3 to 'gameactor' (function expected, got number)")
 
+checkfail("do local bt=require'bittest'; bt.QWE=1; end", "modifying module table forbidden")
+
 
 printf('ceilingbunch of sector 0: %d', getbunch(0, gv.CEILING))