web_handler.erl

abspath(Path)->
    Bits = filename:split(Path),
  
    Folder = fun(Elem, Acc)->
		     case Elem of
			 ".." ->
			     [ lists:nth(Seq, Acc) || Seq <- lists:seq(1, length(Acc)), Seq < length(Acc)  ];
			 _ ->
			     Acc ++ [Elem]
		     end
	     end,  
    filename:join(lists:foldl(Folder, [], Bits)).


-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
abspath_test()->
    ?assertEqual("/home/foo", abspath("/home/bar/../foo")),
    ?assertEqual("/etc/foo", abspath("/home/bar/../../etc/foo")).
-endif.