class Gem::Package::FileSource

def initialize(path)
  @path = path
end

def present?
  File.exist? path
end

def start
  @start ||= File.read path, 20
end

def with_read_io(&block)
  File.open path, 'rb', &block
end

def with_write_io(&block)
  File.open path, 'wb', &block
end