# File lib/rpm/rpmfile.rb, line 52
  def header
    signature

    # Skip 4 bytes of nulls
    # Why? I have no idea yet.
    if @file.read(4) != "\0\0\0\0"
      raise "Expected 4 nulls."
    end

    if @header.nil?
      @header = ::RPMFile::Header.new(self)
      @header.read
    end
    return @header
  end