normalize_path

# File lib/webrick/httputils.rb, line 21
    def normalize_path(path)
      raise "abnormal path `#{path}'" if path[0] != ?/
      ret = path.dup

      ret.gsub!(%r{/+}o, '/')                    # //      => /
      while ret.sub!(%r'/\.(?:/|\Z)', '/'); end  # /.      => /
      while ret.sub!(%r'/(?!\.\./)[^/]+/\.\.(?:/|\Z)', '/'); end # /foo/.. => /foo

      raise "abnormal path `#{path}'" if %r{/\.\.(/|\Z)} =~ ret
      ret
    end