module Backports

def self.combine_mode_and_option(mode = nil, options = Backports::Undefined)
  # Can't backport autoclose, {internal|external|}encoding
  mode, options = nil, mode if mode.respond_to?(:to_hash) && options == Backports::Undefined
  options = {} if options == nil || options == Backports::Undefined
  options = coerce_to_hash(options)
  if mode && options[:mode]
    raise ArgumentError, "mode specified twice"
  end
  mode ||= options[:mode] || "r"
  mode = try_convert(mode, String, :to_str) || try_convert(mode, Integer, :to_int) || mode
  if options[:textmode] || options[:binmode]
    text = options[:textmode] || (mode.is_a?(String) && mode =~ /t/)
    bin  = options[:binmode]  || (mode.is_a?(String) ? mode =~ /b/ : mode & File::Constants::BINARY != 0)
    if text && bin
      raise ArgumentError, "both textmode and binmode specified"
    end
    case
      when !options[:binmode]
      when mode.is_a?(String)
        mode.insert(1, "b")
      else
        mode |= File::Constants::BINARY
    end
  end
  mode
end