# File lib/rbreadline.rb, line 2091
  def rl_read_init_file(filename)
    # Default the filename.
    filename ||= @last_readline_init_file
    filename ||= ENV["INPUTRC"]
    if (filename.nil? || filename == '')
      filename = DEFAULT_INPUTRC
      # Try to read DEFAULT_INPUTRC; fall back to SYS_INPUTRC on failure
      if (_rl_read_init_file(filename, 0) == 0)
        return 0
      end
      filename = SYS_INPUTRC
    end

    if RUBY_PLATFORM =~ /mswin|mingw/
      return 0 if (_rl_read_init_file(filename, 0) == 0)
      filename = "~/_inputrc"
    end
    return (_rl_read_init_file(filename, 0))
  end