copy(pathbuf, prefix)
	n := len(path)
	r, w := 0, len(prefix)
	for r < n {
		switch {
		case os.IsPathSeparator(path[r]):
			// empty block
			r++
		case path[r] == '.' && (r+1 == n || os.IsPathSeparator(path[r+1])):
			// /./
			r++
		case r+1 < n && path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
			// /../ is currently unhandled
			return path
		default:
			pathbuf[w] = '\\'

			return nil
		}
	}

	// Slow path: make sure parent exists and then call Mkdir for path.
	i := len(dirPath)
	for i > 0 && os.IsPathSeparator(dirPath[i-1]) { // Skip trailing path separator.
		i--
	}

	j := i
	for j > 0 && !os.IsPathSeparator(dirPath[j-1]) { // Scan backward over element.
		j--
	}

	if j > 1 {
		// Create parent.
		if err := osMkdirAll(dirPath[:j-1], perm, baseDir); err != nil {

pkg os, func Getuid() int
pkg os, func Getwd() (string, error)
pkg os, func Hostname() (string, error)
pkg os, func IsExist(error) bool
pkg os, func IsNotExist(error) bool
pkg os, func IsPathSeparator(uint8) bool
pkg os, func IsPermission(error) bool
pkg os, func Lchown(string, int, int) error
pkg os, func Link(string, string) error
pkg os, func Lstat(string) (FileInfo, error)