From d2ebdc045bae7c8ed0e62729ca455444c076b1bb Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 18 Feb 2009 14:20:56 -0300
Subject: [PATCH] new macro 'lua_checkversion' to check whether core and
 application are compatible

---
 lapi.c    | 12 +++++++++++-
 lauxlib.c |  3 ++-
 lstate.c  |  3 ++-
 lstate.h  |  3 ++-
 lua.h     |  6 +++++-
 5 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/lapi.c b/lapi.c
index 9af75b17..86b591c4 100644
--- a/lapi.c
+++ b/lapi.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lapi.c,v 2.67 2008/07/04 18:27:11 roberto Exp roberto $
+** $Id: lapi.c,v 2.68 2008/08/01 17:01:16 roberto Exp roberto $
 ** Lua API
 ** See Copyright Notice in lua.h
 */
@@ -121,6 +121,16 @@ LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) {
 }
 
 
+LUA_API void lua_checkversion_ (lua_State *L, int version) {
+  lua_lock(L);
+  if (version != LUA_VERSION_NUM)
+    luaG_runerror(L, "application and Lua core using different Lua versions");
+  if (G(L)->nilobjp != luaO_nilobject)
+    luaG_runerror(L, "application using two incompatible Lua VMs");
+  lua_unlock(L);
+}
+
+
 
 /*
 ** basic stack manipulation
diff --git a/lauxlib.c b/lauxlib.c
index 55ee1411..469553ae 100644
--- a/lauxlib.c
+++ b/lauxlib.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lauxlib.c,v 1.180 2009/02/13 19:39:34 roberto Exp roberto $
+** $Id: lauxlib.c,v 1.181 2009/02/17 14:31:16 roberto Exp roberto $
 ** Auxiliary functions for building Lua libraries
 ** See Copyright Notice in lua.h
 */
@@ -585,6 +585,7 @@ static int libsize (const luaL_Reg *l) {
 
 LUALIB_API void luaL_register (lua_State *L, const char *libname,
                                const luaL_Reg *l) {
+  lua_checkversion(L);
   if (libname) {
     /* check whether lib already exists */
     luaL_findtable(L, LUA_REGISTRYINDEX, "_LOADED", 1);
diff --git a/lstate.c b/lstate.c
index be7eed91..e1a3237b 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.c,v 2.47 2008/08/26 13:27:42 roberto Exp roberto $
+** $Id: lstate.c,v 2.48 2009/02/17 19:47:58 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -175,6 +175,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
   setnilvalue(registry(L));
   luaZ_initbuffer(L, &g->buff);
   g->panic = NULL;
+  g->nilobjp = luaO_nilobject;
   g->gcstate = GCSpause;
   g->rootgc = obj2gco(L);
   g->sweepstrgc = 0;
diff --git a/lstate.h b/lstate.h
index c4106562..def5d7eb 100644
--- a/lstate.h
+++ b/lstate.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lstate.h,v 2.35 2008/08/13 17:01:33 roberto Exp roberto $
+** $Id: lstate.h,v 2.36 2008/08/26 13:27:42 roberto Exp roberto $
 ** Global State
 ** See Copyright Notice in lua.h
 */
@@ -134,6 +134,7 @@ typedef struct global_State {
   UpVal uvhead;  /* head of double-linked list of all open upvalues */
   struct Table *mt[NUM_TAGS];  /* metatables for basic types */
   TString *tmname[TM_N];  /* array with tag-method names */
+  const TValue *nilobjp;  /* pointer to nil object (to check consistency) */
 } global_State;
 
 
diff --git a/lua.h b/lua.h
index aa3a6789..82101882 100644
--- a/lua.h
+++ b/lua.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lua.h,v 1.230 2008/07/18 19:58:10 roberto Exp roberto $
+** $Id: lua.h,v 1.231 2008/08/13 14:08:49 roberto Exp roberto $
 ** Lua - An Extensible Extension Language
 ** Lua.org, PUC-Rio, Brazil (http://www.lua.org)
 ** See Copyright Notice at the end of this file
@@ -115,6 +115,10 @@ LUA_API lua_State *(lua_newthread) (lua_State *L);
 LUA_API lua_CFunction (lua_atpanic) (lua_State *L, lua_CFunction panicf);
 
 
+LUA_API void lua_checkversion_ (lua_State *L, int version);
+#define lua_checkversion(L)	(lua_checkversion_(L, LUA_VERSION_NUM))
+
+
 /*
 ** basic stack manipulation
 */