func copyCppConfigsToTarball()

in pkg/rbeconfigsgen/rbeconfigsgen.go [687:730]
38 lines of code
10 McCabe index (conditional complexity)

func copyCppConfigsToTarball(inTarPath string, outTar *tar.Writer) error {
	in, err := os.Open(inTarPath)
	if err != nil {
		return fmt.Errorf("unable to open input tarball %q for reading: %w", inTarPath, err)
	}
	defer in.Close()
	inTar := tar.NewReader(in)
	pathPrefix := "cc"

	for {
		h, err := inTar.Next()
		if err == io.EOF {
			break
		}
		if err != nil {
			return fmt.Errorf("error while reading input tarball %q: %w", inTarPath, err)
		}
		switch h.Typeflag {
		case tar.TypeDir:
			break
		case tar.TypeReg:
			if strings.HasSuffix(h.Name, "WORKSPACE") {
				break
			}
			outH := *h
			// Update the name to be in a 'cc' directory and set the mod time to epoch because:
			// 1. The output becomes deterministic.
			// 2. The mod times of the files archived inside the toolchain container sometimes
			//    seem to be well into the future and I didn't bother figuring out why. Maybe it
			//    only happens on my machine (shrug).
			outH.Name = path.Join(pathPrefix, h.Name)
			outH.ModTime = time.Unix(0, 0)
			if err := outTar.WriteHeader(&outH); err != nil {
				return fmt.Errorf("error while adding tar header for %q from input tarball to output tarball: %w", h.Name, err)
			}
			if _, err := io.Copy(outTar, inTar); err != nil {
				return fmt.Errorf("failed to copy the contents of %q from intput tarball to the output tarball: %w", h.Name, err)
			}
		default:
			return fmt.Errorf("got unexpected entry with name %q of type %v in tarball %q: %w", h.Name, h.Typeflag, inTarPath, err)
		}
	}
	return nil
}