func (s *HTTPStaticServer) getRealPath(r *http.Request) string {
	path := mux.Vars(r)["path"]
	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}
	path = filepath.Clean(path) // prevent .. for safe issues
	relativePath, err := filepath.Rel(s.Prefix, path)
	if err != nil {
		relativePath = path
	}
	realPath := filepath.Join(s.Root, relativePath)
	return filepath.ToSlash(realPath)
}


func (s *HTTPStaticServer) hIndex(w http.ResponseWriter, r *http.Request) {
    path := mux.Vars(r)["path"]
    realPath := s.getRealPath(r)
    if r.FormValue("json") == "true" {
        s.hJSONList(w, r)
        return
    }

    if r.FormValue("op") == "info" {
        s.hInfo(w, r)
        return
    }

    if r.FormValue("op") == "archive" {
        s.hZip(w, r)
        return
    }

    log.Println("GET", path, realPath)
    if r.FormValue("raw") == "false" || isDir(realPath) {
        if r.Method == "HEAD" {
            return
        }
        renderHTML(w, "assets/index.html", s)
    } else {
        if filepath.Base(path) == YAMLCONF {
            auth := s.readAccessConf(realPath)
            if !auth.Delete {
                http.Error(w, "Security warning, not allowed to read", http.StatusForbidden)
                return
            }
        }
        if r.FormValue("download") == "true" {
            w.Header().Set("Content-Disposition", "attachment; filename="+strconv.Quote(filepath.Base(path)))
        }
        http.ServeFile(w, r, realPath)
    }
}

func Clean(path string) string {
	originalPath := path
	volLen := volumeNameLen(path)
	path = path[volLen:]
	if path == "" {
		if volLen > 1 && originalPath[1] != ':' {
			// should be UNC
			return FromSlash(originalPath)
		}
		return originalPath + "."
	}
	rooted := os.IsPathSeparator(path[0])

	// Invariants:
	//	reading from path; r is index of next byte to process.
	//	writing to buf; w is index of next byte to write.
	//	dotdot is index in buf where .. must stop, either because
	//		it is the leading slash or it is a leading ../../.. prefix.
	n := len(path)
	out := lazybuf{path: path, volAndPath: originalPath, volLen: volLen}
	r, dotdot := 0, 0
	if rooted {
		out.append(Separator)
		r, dotdot = 1, 1
	}

	for r < n {
		switch {
		case os.IsPathSeparator(path[r]):
			// empty path element
			r++
		case path[r] == '.' && r+1 == n:
			// . element
			r++
		case path[r] == '.' && os.IsPathSeparator(path[r+1]):
			// ./ element
			r++

			for r < len(path) && os.IsPathSeparator(path[r]) {
				r++
			}
			if out.w == 0 && volumeNameLen(path[r:]) > 0 {
				// When joining prefix "." and an absolute path on Windows,
				// the prefix should not be removed.
				out.append('.')
			}
		case path[r] == '.' && path[r+1] == '.' && (r+2 == n || os.IsPathSeparator(path[r+2])):
			// .. element: remove to last separator
			r += 2
			switch {
			case out.w > dotdot:
				// can backtrack
				out.w--
				for out.w > dotdot && !os.IsPathSeparator(out.index(out.w)) {
					out.w--
				}
			case !rooted:
				// cannot backtrack, but not rooted, so append .. element.
				if out.w > 0 {
					out.append(Separator)
				}
				out.append('.')
				out.append('.')
				dotdot = out.w
			}
		default:
			// real path element.
			// add slash if needed
			if rooted && out.w != 1 || !rooted && out.w != 0 {
				out.append(Separator)
			}
			// copy element
			for ; r < n && !os.IsPathSeparator(path[r]); r++ {
				out.append(path[r])
			}
		}
	}

	// Turn empty string into "."
	if out.w == 0 {
		out.append('.')
	}

	return FromSlash(out.string())
}

func join(elem []string) string {
	// If there's a bug here, fix the logic in ./path_plan9.go too.
	for i, e := range elem {
		if e != "" {
			return Clean(strings.Join(elem[i:], string(Separator)))
		}
	}
	return ""
}

func volumeNameLen(path string) int {
	if len(path) < 2 {
		return 0
	}
	// with drive letter
	c := path[0]
	if path[1] == ':' && ('a' <= c && c <= 'z' || 'A' <= c && c <= 'Z') {
		return 2
	}
	// is it UNC? https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx
	if l := len(path); l >= 5 && isSlash(path[0]) && isSlash(path[1]) &&
		!isSlash(path[2]) && path[2] != '.' {
		// first, leading `\\` and next shouldn't be `\`. its server name.
		for n := 3; n < l-1; n++ {
			// second, next '\' shouldn't be repeated.
			if isSlash(path[n]) {
				n++
				// third, following something characters. its share name.
				if !isSlash(path[n]) {
					if path[n] == '.' {
						break
					}
					for ; n < l; n++ {
						if isSlash(path[n]) {
							break
						}
					}
					return n
				}
				break
			}
		}
	}
	return 0
}
func join(elem []string) string {
	for i, e := range elem {
		if e != "" {
			return joinNonEmpty(elem[i:])
		}
	}
	return ""
}

// joinNonEmpty is like join, but it assumes that the first element is non-empty.
func joinNonEmpty(elem []string) string {
	if len(elem[0]) == 2 && elem[0][1] == ':' {
		// First element is drive letter without terminating slash.
		// Keep path relative to current directory on that drive.
		// Skip empty elements.
		i := 1
		for ; i < len(elem); i++ {
			if elem[i] != "" {
				break
			}
		}
		return Clean(elem[0] + strings.Join(elem[i:], string(Separator)))
	}
	// The following logic prevents Join from inadvertently creating a
	// UNC path on Windows. Unless the first element is a UNC path, Join
	// shouldn't create a UNC path. See golang.org/issue/9167.
	p := Clean(strings.Join(elem, string(Separator)))
	if !isUNC(p) {
		return p
	}
	// p == UNC only allowed when the first element is a UNC path.
	head := Clean(elem[0])
	if isUNC(head) {
		return p
	}
	// head + tail == UNC, but joining two non-UNC paths should not result
	// in a UNC path. Undo creation of UNC path.
	tail := Clean(strings.Join(elem[1:], string(Separator)))
	if head[len(head)-1] == Separator {
		return head + tail
	}
	return head + string(Separator) + tail
}

// isUNC reports whether path is a UNC path.
func isUNC(path string) bool {
	return volumeNameLen(path) > 2
}

func sameWord(a, b string) bool {
	return strings.EqualFold(a, b)
}