Function getupvalref

depends/lua/src/lapi.c:1257–1264

static UpVal **getupvalref (lua_State *L, int fidx, int n) {
  LClosure *f;
  StkId fi = index2addr(L, fidx);
  api_check(L, ttisLclosure(fi), "Lua function expected");
  f = clLvalue(fi);
  api_check(L, (1 <= n && n <= f->p->sizeupvalues), "invalid upvalue index");
  return &f->upvals[n - 1];  /* get its upvalue pointer */
}


LUA_API void *lua_upvalueid (lua_State *L, int fidx, int n) {