gistfile1.rb

#! /usr/bin/env ruby
# vim: ai ts=2 sts=2 sw=2 expandtab

require 'pty'
require 'time'

exit 1 if ARGV.count == 0

output = ARGV.first
if ARGV.count == 1
  File.delete(output) if File.exists?(output)
  cmd = "ruby #{__FILE__} #{output} x"      # ok
  cmd = "ruby #{__FILE__} #{output} x 2>&1" # not ok

  timeout = 1.0
  stdin, stdout, pid = PTY.spawn(cmd)
  timeout_at = Time.now + timeout
  loop do
    begin
      data = stdin.read_nonblock(1024)
      print data
      timeout_at = Time.now + timeout
    rescue Errno::EAGAIN
      sleep 0.1
    rescue EOFError
      $stderr.puts "\nprocess EOF?"
      Process.wait(pid)
      raise
    rescue Errno::EIO
      x = Process.wait(pid)
      exit $?.exitstatus
    end
    if Time.now >= timeout_at
      puts
      puts "output size before: #{File.size?(output)}"
      Process.kill('HUP', pid)
      puts "output size during: #{File.size?(output)}"
      Process.wait(pid)
      puts "output size after (1): #{File.size?(output)}"
      sleep 1.0 # XXX: magic sleep
      puts "output size after (2): #{File.size?(output)}"
      exit 1
    end
  end
else
  File.open(output, 'w') do |file|
    trap("HUP") do
      file.puts "END"
      file.flush
      exit
    end
    file.puts "a"
    file.flush
    $stdout.puts "out"
    $stderr.puts "err"
    sleep 1.5
    file.puts "not reached"
    file.flush
  end
end