Lua获取文件长度和判断文件是否存在函数分享

 function length_of_file(filename)
  local fh = assert(io.open(filename, "rb"))
  local len = assert(fh:seek("end"))
  fh:close()
  return len
end

function file_exists(path)
  local file = io.open(path, "rb")
  if file then file:close() end
  return file ~= nil
end