--- C:/dev/luas/lua-5.2.0/src/lparser.c	Fri Dec 2 05:23:56 2011
+++ C:/dev/luas/lua-5.2.0/src/lparser_safe.c	Sun Mar 3 17:56:46 2013
@@ -306,6 +306,16 @@
 }
 }
 
+static void singlevar_from_string (LexState *ls, expdesc *var, TString *varname) {
+ FuncState *fs = ls->fs;
+ if (singlevaraux(fs, varname, var, 1) == VVOID) { /* global name? */
+ expdesc key;
+ singlevaraux(fs, ls->envn, var, 1); /* get environment variable */
+ lua_assert(var->k == VLOCAL || var->k == VUPVAL);
+ codestring(ls, &key, varname); /* key is variable name */
+ luaK_indexed(fs, var, &key); /* env[varname] */
+ }
+}
 
 static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
 FuncState *fs = ls->fs;
@@ -571,6 +581,18 @@
 L->top--; /* pop prototype (after possible collection) */
 }
 
+/* 
+** start the function with an implicit line:
+** local _SAFE = _SAFE
+*/
+static void safe_local(LexState * ls) {
+ expdesc v;
+ TString * safe = luaX_newstring ( ls, "_SAFE", 5);
+ singlevar_from_string(ls,&v,safe);
+ luaK_exp2nextreg(ls->fs,&v);
+ new_localvar(ls,safe);
+ adjustlocalvars(ls, 1);
+}
 
 /*
 ** opens the main function, which is a regular vararg function with an
@@ -582,6 +604,7 @@
 fs->f->is_vararg = 1; /* main function is always vararg */
 init_exp(&v, VLOCAL, 0);
 newupvalue(fs, ls->envn, &v); /* create environment upvalue */
+ safe_local(ls);
 }
 
 
@@ -909,6 +932,18 @@
 prefixexp(ls, v);
 for (;;) {
 switch (ls->t.token) {
+ case '?': { /* safe navigation */
+ expdesc safe;
+ luaX_next(ls);
+ enterlevel(ls);
+ luaK_infix(fs,OPR_OR,v);
+ if( singlevaraux(fs, luaX_newstring ( ls, "_SAFE", 5), &safe, 1) == VVOID) {
+ luaX_syntaxerror(ls, "the _SAFE upvalue is missing");
+ }
+ luaK_posfix(fs, OPR_OR, v, &safe, line);
+ leavelevel(ls);
+ break;
+ }
 case '.': { /* fieldsel */
 fieldsel(ls, v);
 break;
--- C:/dev/luas/lua-5.2.0/src/lstate.c	Mon Oct 3 10:54:25 2011
+++ C:/dev/luas/lua-5.2.0/src/lstate_safe.c	Sun Mar 3 18:04:47 2013
@@ -224,6 +224,22 @@
 luaM_free(L, l);
 }
 
+/* Define the global _SAFE userdata. */
+static int _nullop(lua_State *L) {return 0;}
+static int _nullitr(lua_State *L) { lua_pushcfunction(L,_nullop); return 1; }
+static void register_safe(lua_State *L) {
+ lua_newuserdata(L,0);
+ lua_createtable(L,0,5);
+#define nullmeta(fun) lua_pushcfunction(L,_nullop); lua_setfield(L,-2,fun);
+ lua_pushcfunction(L,_nullitr); lua_setfield(L,-2,"__pairs");
+ lua_pushcfunction(L,_nullitr); lua_setfield(L,-2,"__ipairs");
+ nullmeta("__index")
+ nullmeta("__newindex")
+ nullmeta("__call")
+#undef nullmeta
+ lua_setmetatable(L,-2);
+ lua_setglobal(L,"_SAFE");
+}
 
 LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
 int i;
@@ -272,6 +288,7 @@
 }
 else
 luai_userstateopen(L);
+ register_safe(L);
 return L;
 }
 
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="http://lua-users.org/files/wiki_insecure/power_patches/5.2/safe.patch">(-&gt;オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="http://lua-users.org/files/wiki_insecure/power_patches/5.2/safe.patch" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>