commit 32a5d96dfc846ccfe63e6272d385fe963e025b61
parent 8dae071f42bf036ea3f61468aca825397c8e33e4
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Mon, 16 Sep 2002 16:49:23 -0300
`setmetatable' cannot change protected objects
Diffstat:
3 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/lauxlib.c b/lauxlib.c
@@ -1,5 +1,5 @@
/*
-** $Id: lauxlib.c,v 1.84 2002/08/30 20:00:59 roberto Exp roberto $
+** $Id: lauxlib.c,v 1.85 2002/09/05 19:45:42 roberto Exp roberto $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h
*/
@@ -147,7 +147,7 @@ LUALIB_API lua_Number luaL_opt_number (lua_State *L, int narg, lua_Number def) {
}
-LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
+LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *event) {
if (!lua_getmetatable(L, obj)) /* no metatable? */
return 0;
lua_pushstring(L, event);
@@ -156,6 +156,13 @@ LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
lua_pop(L, 2); /* remove metatable and metafield */
return 0;
}
+ return 1;
+}
+
+
+LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *event) {
+ if (!luaL_getmetafield(L, obj, event)) /* no metafield? */
+ return 0;
lua_pushvalue(L, obj);
lua_call(L, 1, 1);
return 1;
diff --git a/lauxlib.h b/lauxlib.h
@@ -1,5 +1,5 @@
/*
-** $Id: lauxlib.h,v 1.52 2002/08/08 20:08:41 roberto Exp roberto $
+** $Id: lauxlib.h,v 1.53 2002/08/30 20:00:59 roberto Exp roberto $
** Auxiliary functions for building Lua libraries
** See Copyright Notice in lua.h
*/
@@ -30,6 +30,7 @@ typedef struct luaL_reg {
LUALIB_API void luaL_openlib (lua_State *L, const luaL_reg *l, int nup);
LUALIB_API void luaL_opennamedlib (lua_State *L, const char *libname,
const luaL_reg *l, int nup);
+LUALIB_API int luaL_getmetafield (lua_State *L, int obj, const char *e);
LUALIB_API int luaL_callmeta (lua_State *L, int obj, const char *e);
LUALIB_API int luaL_typerror (lua_State *L, int narg, const char *tname);
LUALIB_API int luaL_argerror (lua_State *L, int numarg, const char *extramsg);
diff --git a/lbaselib.c b/lbaselib.c
@@ -1,5 +1,5 @@
/*
-** $Id: lbaselib.c,v 1.97 2002/08/08 20:08:41 roberto Exp roberto $
+** $Id: lbaselib.c,v 1.98 2002/09/05 19:45:42 roberto Exp roberto $
** Basic library
** See Copyright Notice in lua.h
*/
@@ -109,14 +109,8 @@ static int luaB_getmetatable (lua_State *L) {
lua_pushnil(L);
return 1; /* no metatable */
}
- else {
- lua_pushliteral(L, "__metatable");
- lua_rawget(L, -2);
- if (lua_isnil(L, -1))
- lua_pop(L, 1);
- /* otherwise returns metatable.__metatable */
- }
- return 1;
+ luaL_getmetafield(L, 1, "__metatable");
+ return 1; /* returns either __metatable field (if present) or metatable */
}
@@ -125,6 +119,8 @@ static int luaB_setmetatable (lua_State *L) {
luaL_check_type(L, 1, LUA_TTABLE);
luaL_arg_check(L, t == LUA_TNIL || t == LUA_TTABLE, 2,
"nil or table expected");
+ if (luaL_getmetafield(L, 1, "__metatable"))
+ luaL_error(L, "cannot change a protected metatable");
lua_settop(L, 2);
lua_setmetatable(L, 1);
return 1;