1 files changed, 37 insertions, 0 deletions
diff --git a/examples/web_server/src/directory_lister.erl b/examples/web_server/src/directory_lister.erl
new file mode 100644
index 0000000..a59f957
--- /dev/null
+++ b/examples/web_server/src/directory_lister.erl
@@ -0,0 +1,37 @@
+%% Feel free to use, reuse and abuse the code in this file.
+
+-module(directory_lister).
+-behaviour(cowboy_middleware).
+
+-export([execute/2]).
+
+execute(Req, Env) ->
+	case lists:keyfind(handler, 1, Env) of
+		{handler, cowboy_static} -> redirect_directory(Req, Env);
+		_H -> {ok, Req, Env}
+	end.
+
+redirect_directory(Req, Env) ->
+	{Path, Req1} = cowboy_req:path_info(Req),
+	Path1 = << <<S/binary, $/>> || S <- Path >>,
+	{handler_opts, StaticOpts} = lists:keyfind(handler_opts, 1, Env),
+	{dir_handler, DirHandler} = lists:keyfind(dir_handler, 1, StaticOpts),
+	FullPath = resource_path(Path1),
+	case valid_path(Path) and filelib:is_dir(FullPath) of
+		true -> handle_directory(Req1, Env, Path1, FullPath, DirHandler);
+		false -> {ok, Req1, Env}
+	end.
+
+handle_directory(Req, Env, Prefix, Path, DirHandler) ->
+	Env1 = lists:keydelete(handler, 1,
+		lists:keydelete(handler_opts, 1, Env)),
+	{ok, Req, [{handler, DirHandler}, {handler_opts, {Prefix, Path}} | Env1]}.
+
+valid_path([]) -> true;
+valid_path([<<"..">> | _T]) -> false;
+valid_path([<<"/", _/binary>> | _T]) -> false;
+valid_path([_H | Rest]) -> valid_path(Rest).
+
+resource_path(Path) ->
+	{ok, Cwd} = file:get_cwd(),
+	filename:join([Cwd, "priv", Path]).