io_hasher.rb: digests an IO

io_hasher.rb

require 'digest'

class IOHasher
  def initialize(digest=Digest::MD5.new, buf='\0' * 4096)
    @digest = digest
    @buf = buf
    @chunk_size = buf.size
  end

  def hash_of(io)
    @buf.clear
    while io.read(@chunk_size, @buf) && !@buf.empty?
      @digest << @buf
    end
    @digest.digest!
  end
end