Function lua_getupvalue

3rd/lua-5.4.3/src/lapi.c:1376–1387

LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
  const char *name;
  TValue *val = NULL;  /* to avoid warnings */
  lua_lock(L);
  name = aux_upvalue(index2value(L, funcindex), n, &val, NULL);
  if (name) {
    setobj2s(L, L->top, val);
    api_incr_top(L);
  }
  lua_unlock(L);
  return name;
}


LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {