explicit stack control in the API

liolib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: liolib.c,v 1.72 2000/08/28 17:57:04 roberto Exp roberto $
+** $Id: liolib.c,v 1.73 2000/08/29 14:33:31 roberto Exp roberto $
 ** Standard I/O (and system) library
 ** See Copyright Notice in lua.h
 */
@@ -372,6 +372,7 @@ static int io_read (lua_State *L) {
     firstarg = lastarg = 1;  /* correct indices */
     lua_pushstring(L, "*l");  /* push default argument */
   }
+  luaL_checkstack(L, lastarg-firstarg+1, "too many results");
   for (n = firstarg; n<=lastarg; n++) {
     size_t l;
     int success;