Bug in `partitionDOS()`?

[michalfita]

In the function partitionDOS() I had to make change to get this to work:

func partitionDOS(ui packer.Ui, config *Config) multistep.StepAction {
	lines := []string{
		"label: dos",
		fmt.Sprintf("device: %s", config.ImageConfig.ImagePath),
		"unit: sectors",
	}

	ui.Message(
		fmt.Sprintf("creating %d dos partitions on %s",
			len(config.ImageConfig.ImagePartitions),
			config.ImageConfig.ImagePath),
	)
	for i, partition := range config.ImageConfig.ImagePartitions {
		line := fmt.Sprintf(
			"%s%d: type=%s",
			partition.Name, //config.ImageConfig.ImagePath,
			i+1,
			partition.Type,
		)
        // ...	

the line input fed into sfdisk shall contain partition names declared, not path to the image. Then to get any output from stderr I had to add:

stderr, err := cmd.StderrPipe()
	if err != nil {
		ui.Error(fmt.Sprintf("error while getting stderr pipe %v", err))
		return multistep.ActionHalt
	}
	defer stderr.Close()

and replace:

out, _ := io.ReadAll(stdout)

with

out, _ := io.ReadAll(stderr)

But I'm by any means Go expert and these can probably be fixed in a better way.