silly piper

piper.rb

READ_BUF = 1024
HIGH_WATER = 1024

$fin = nil
$fout = nil

def open_fin
  if $fin.nil? || ($fin.is_a?(File) && ($fin.eof? || $fin.closed?))

    if File.exists?(ARGV[0])
      unless File.pipe?(ARGV[0])
        puts "#{ARGV[0]} is not a pipe"
        exit
      end
    else
      system("mkfifo #{ARGV[0]}")
    end

    $fin = File.open(ARGV[0],'r+')
  end
end

def open_fout
  if $fout.nil? || ($fout.is_a?(File) && $fout.closed?)
    $fout = File.open(ARGV[1],'a+')
  end
end

def reset
  $a = ""
  $idx = 0
end

def write_out(extra = :none)
  if $fout.closed?
    open_fin
  end
  $fout.write($a)
  $fout.flush
  $fout.fsync
  if extra == :close
    $fout.close
  end
end

Signal.trap("INT") do
  write_out :close
  File.unlink(ARGV[0]) if File.exist?(ARGV[0]) && File.pipe?(ARGV[0])
  puts "bye"
  exit
end

reset

while true

  open_fin

  open_fout

  begin
    while data = $fin.readpartial(READ_BUF)
      $a += data
      $idx += 1
      if $idx > HIGH_WATER
        write_out
        reset
      end
    end
  rescue EOFError => e
    write_out
    reset
  end
end