GzipCat in Ruby using pipes and FIFO

gzip_cat.rb

module GzipCat
  class File
    def initialize(file)
      # puts "FILE => #{file}"
      @filename = file
      begin
        @content = open(::File.expand_path(filename)).read
        cat!
      rescue Exception => e
        # File not found and other errors are reported
        puts e.message
      end
    end
    attr_accessor :filename, :content

    def cat!
      # checks if the file is compressed
      if ::File.extname(filename) == ".gz"
        unzip!
      else
        puts content
      end
    end

    def unzip!
      # creates pipe descriptors
      rd, wr = IO.pipe

      if fork
        # closes unused pipe side
        rd.close
        # sends file content into the pipe
        wr.write content
        wr.close

        # waits for child process to respect files order
        Process.wait
      else
        # closes unused pipe side
        wr.close
        # redirects $stdin to pipe descriptor - i.e. dup2 in clang
        $stdin.reopen(rd)
        # invokes gzip
        exec("gzip -d")
      end
    end
  end

  class Server
    def self.start(fifo_path)
      puts "[#{Time.now}] GzipCat server connected into #{fifo_path} fifo"
      # opens fifo on read mode
      input = open(fifo_path, 'r')

      # keeps the server alive
      loop do
        # puts "Wait"
        # gets fifo content blocking if no content has been got
        File.new(input.gets.chomp)
      end
    end
  end
end



# run server
GzipCat::Server.start(ARGV.first)

# rd, wr = IO.pipe

# if fork
#   wr.close
#   $stdin.reopen(rd)
#   exec("gzip -d")
#   rd.close
#   # wait
# else
#   rd.close
#   wr.write open("./test.txt.gz").read
#   wr.close
# end