func untar()

in pkg/fetch/fetch.go [137:215]
69 lines of code
22 McCabe index (conditional complexity)

func untar(dir string, r io.Reader, stripComponents int) error {
	gzr, err := gzip.NewReader(r)
	if err != nil {
		return gcp.InternalErrorf("creating gzip reader: %v", err)
	}
	defer gzr.Close()

	madeDir := map[string]bool{}
	tr := tar.NewReader(gzr)

	for {
		header, err := tr.Next()

		switch {
		case err == io.EOF:
			return nil
		case err != nil:
			return gcp.InternalErrorf("untaring file: %v", err)
		case header == nil:
			continue
		}

		target, err := tarDestination(header.Name, dir, header.Typeflag, stripComponents)
		if err != nil {
			return err
		}

		switch header.Typeflag {
		case tar.TypeDir:
			if _, err := os.Stat(target); err != nil {
				if err := os.Mkdir(target, os.FileMode(header.Mode)); err != nil {
					return gcp.InternalErrorf("creating directory %q: %v", target, err)
				}
				madeDir[target] = true
			}
		case tar.TypeReg, tar.TypeRegA:
			// Make the directory. This is redundant because it should
			// already be made by a directory entry in the tar
			// beforehand. Thus, don't check for errors; the next
			// write will fail with the same error.
			dir := filepath.Dir(target)
			if !madeDir[dir] {
				if err := os.MkdirAll(dir, 0755); err != nil {
					return gcp.InternalErrorf("creating directory %q: %v", target, err)
				}
				madeDir[dir] = true
			}

			f, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR, os.FileMode(header.Mode))
			if err != nil {
				return gcp.InternalErrorf("opening file %q: %v", target, err)
			}
			if _, err := io.Copy(f, tr); err != nil {
				return gcp.InternalErrorf("copying file %q: %v", target, err)
			}
			if err := f.Close(); err != nil {
				return gcp.InternalErrorf("closing file %q: %v", target, err)
			}
		case tar.TypeSymlink:
			targetPath := filepath.Join(filepath.Dir(target), header.Linkname)
			if !isValidTarDestination(targetPath, dir, header.Typeflag) {
				return gcp.InternalErrorf("symlink %q -> %q traverses out of root", target, header.Linkname)
			}
			if err := os.Symlink(header.Linkname, target); err != nil {
				return gcp.InternalErrorf("symlinking %q to %q: %v", target, header.Linkname, err)
			}
		case tar.TypeLink:
			link, err := tarDestination(header.Linkname, dir, header.Typeflag, stripComponents)
			if err != nil {
				return err
			}
			if err := os.Link(link, target); err != nil {
				return gcp.InternalErrorf("linking %q to %q: %v", target, link, err)
			}
		default:
			return gcp.InternalErrorf("invalid tar entry %v", header)
		}
	}
}