luatex problem with file with umlauts on windows 10

[Akira Kakuto]

Dear Ulrike,

> I tried with some chinese (at least I think it is chinese). And
> there is breaks again: the file is input but lfs reports nil:

Sorry. I'm not using true Unicode programing, only a workaround.
Here on Japanese windows, kanji, hiragana etc. work.

Note that, more confusingly, the behavior of texlua is not changed
for compatilility with many existing scripts:

-- an example of texlua script
-- for texlua, UTF-8
kpse.set_program_name('kpsewhich')
local function is_texlive()
  local a = kpse.var_value('command_line_encoding')
  if a then
    return true
  else
    return false
  end
end

local function is_windows()
  if os.type == 'windows' then
    return true
  else
    return false
  end
end

function myfilesize(name)
-- In the case of texlua, kpse can't find UTF-8 name
-- and only can find ANSI name with local code page,
-- for compatibility with many existing scripts.
-- Command line is not changed to UTF-8.
-- Return value is also ANSI name with local code page.
-- If name is in UTF-8, we have to change it to local code page.
  if is_windows() and is_texlive() then
    local nname = chgstrcp.utf8tosyscp(name)
    name = nname
  end
  local file =  kpse.find_file(name, "tex", true)
  print("\nFILE: ",file)
  if file then
    local size = lfs.attributes(file, "size")
    local isfile= lfs.isfile (file)
    print("SIZE: ",size)
    print("isfile ", isfile)
  end
end
myfilesize("grüße.tex")

Best,
Akira