# File lib/chef/mixin/command/windows.rb, line 31
        def popen4(cmd, args={}, &b)

          # By default, we are waiting before we yield the block.
          args[:waitlast] ||= false

          #XXX :user, :group, :environment support?

          Open3.popen3(cmd) do |stdin,stdout,stderr,cid|
            if b
              if args[:waitlast]
                b[cid, stdin, stdout, stderr]
                # send EOF so that if the child process is reading from STDIN
                # it will actually finish up and exit
                stdin.close_write
              else
                o = StringIO.new
                e = StringIO.new

                stdin.close

                stdout.sync = true
                stderr.sync = true

                line = stdout.gets(nil)
                if line
                  o.write(line)
                end
                line = stderr.gets(nil)
                if line
                  e.write(line)
                end
                o.rewind
                e.rewind
                b[cid, stdin, o, e]
              end
            else
              [cid, stdin, stdout, stderr]
            end
          end
          $?
        end