ruby read file from bottom to top until match

ruby-read-file-from-bottom-to-top-until-match

# thank you aperios from #ruby
#! /usr/bin/env ruby

class Rubash
  def tail_match(filename, pattern)
    fd = File.open(filename, 'rb')
    file_byte_size = fd.size
    pos = 0
    result = ''
    result.encode!(Encoding::BINARY)
    match = 0

    while (file_byte_size > -pos) && match.zero? do
      pos -= 1
      fd.seek(pos, IO::SEEK_END)

      result = fd.read(1) + result

      match = 1 if result[0..2] == pattern
    end

    return '' if match.zero?
    result
  end
end

puts Rubash.new.tail_match('test.txt', '---')