なんかアレなやつ

currentlang.lua

local ffi = require("ffi")
ffi.cdef[[
int GetLocaleInfoEx(
  const wchar_t *lpLocaleName,
  unsigned long LCType,
  wchar_t *lpLCData,
  int cchData
);
]]
function to_wstr(str)
  local out = ffi.new("wchar_t[?]", #str+1)
  for i = 1, #str do out[i-1] = str:byte(i) end
  return out
end
function from_wstr(wstr, len)
  local cs = {}
  for i = 1, len do cs[i] = wstr[i-1] end
  return string.char(table.unpack(cs))
end

function current_lang()
  local res = ffi.new("wchar_t[?]", 16)
  local rlen = ffi.C.GetLocaleInfoEx(nil, 3, res, 16)
  if rlen == 0 then return end
  local clcode = from_wstr(res, rlen)
  print("current language = "..clcode)
  local qry = ffi.new("wchar_t[?]", 3)
  for c1 = 97, 122 do for c2 = 97, 122 do
    qry[0], qry[1] = c1, c2
    rlen = ffi.C.GetLocaleInfoEx(qry, 3, res, 16)
    local code = from_wstr(res, rlen)
    if clcode == code then
      print("two-letter code = "..string.char(c1, c2))
    end
  end end
end

current_lang()