Hi Luigi,

> H30/12/27 8:15、luigi scarso <luigi.scarso@gmail.com>のメール:
>
>> On Wed, Dec 26, 2018 at 12:02 PM ARATA Mizuki <minorinoki@gmail.com> wrote:
>> Hi,
>>
>> Even though LuajitTeX has lfs as a built-in library, trying to load it via `require` doesn't work.
>> (LuaTeX with Lua 5.2/5.3 doesn't have this problem)
>>
>> This is because the field package.loaded["lfs"] is not set during initialization.
>>
>> To fix this, change Luas_open to set the module (returned by the module loader) to the package.loaded table, which is available as _LOADED on the registry table.
>>
>> Also, zlib suffers from a similar problem, both on LuaTeX and LuajitTeX.
>>
>> Here is a proposed patch to fix these problems:
>> ...
>>
>> --
>> Mizuki
>
>
> require here is not strictly needed, given that the code below work.
> We will check the code above, but lfs has some security implications
> and zlib is a bit weird to load.
>
> ...
>
> --
> luigi
>

I know it's not needed to do `require "lfs"` on LuaTeX, but people *does* use lfs via require, because it's the standard way to load lfs. A couple of example that does `require "lfs"`:

luamplib: https://github.com/lualatex/luamplib/search?q=lfs&unscoped_q=lfs

A code snippet on stackexchange: https://tex.stackexchange.com/questions/48179/what-is-the-correct-way-to-delineate-directories-in-lua

So `require "lfs"` should be valid on LuajitTeX, too.