class SystemUniversal

def child_setup tmp
  stdin = File.expand_path(File.join(tmp, 'stdin'))
  stdout = File.expand_path(File.join(tmp, 'stdout'))
  stderr = File.expand_path(File.join(tmp, 'stderr'))
  program = File.expand_path(File.join(tmp, 'program'))
  config = File.expand_path(File.join(tmp, 'config'))
  if @stdin
    open(stdin, 'w'){|f| relay @stdin => f}
  else
    FileUtils.touch stdin
  end
  FileUtils.touch stdout
  FileUtils.touch stderr
  c = {}
  c['argv'] = @argv
  c['env'] = @env
  c['cwd'] = @cwd
  c['stdin'] = stdin
  c['stdout'] = stdout
  c['stderr'] = stderr
  c['program'] = program
  open(config, 'w'){|f| Marshal.dump(c, f)}
  open(program, 'w'){|f| f.write child_program(config)}
  c
end