1 files changed, 156 insertions, 0 deletions
diff --git a/lib/kernel/examples/uds_dist/src/uds_server.erl b/lib/kernel/examples/uds_dist/src/uds_server.erl
new file mode 100644
index 0000000000..c060130f9d
--- /dev/null
+++ b/lib/kernel/examples/uds_dist/src/uds_server.erl
@@ -0,0 +1,156 @@
+%%%----------------------------------------------------------------------
+%%% File    : uds_server.erl
+%%% Purpose : Holder for the uds_drv ddll driver.
+%%% Created : 15 Mar 2000 
+%%%----------------------------------------------------------------------
+
+-module(uds_server).
+
+-behaviour(gen_server).
+
+%% External exports
+-export([start_link/0]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+
+-define(DRIVER_NAME,"uds_drv").
+
+%%%----------------------------------------------------------------------
+%%% API
+%%%----------------------------------------------------------------------
+start_link() ->
+    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+%%%----------------------------------------------------------------------
+%%% Callback functions from gen_server
+%%%----------------------------------------------------------------------
+
+%%----------------------------------------------------------------------
+%% Func: init/1
+%% Returns: {ok, State}          |
+%%          {ok, State, Timeout} |
+%%          ignore               |
+%%          {stop, Reason}
+%%----------------------------------------------------------------------
+init([]) ->
+    process_flag(trap_exit,true),
+    case load_driver() of
+	ok ->
+	    {ok, []};
+	{error, already_loaded} ->
+	    {ok, []};
+	Error ->
+	    exit(Error)
+    end.
+
+
+%%----------------------------------------------------------------------
+%% Func: handle_call/3
+%% Returns: {reply, Reply, State}          |
+%%          {reply, Reply, State, Timeout} |
+%%          {noreply, State}               |
+%%          {noreply, State, Timeout}      |
+%%          {stop, Reason, Reply, State}   | (terminate/2 is called)
+%%          {stop, Reason, State}            (terminate/2 is called)
+%%----------------------------------------------------------------------
+handle_call(Request, From, State) ->
+    Reply = ok,
+    {reply, Reply, State}.
+
+%%----------------------------------------------------------------------
+%% Func: handle_cast/2
+%% Returns: {noreply, State}          |
+%%          {noreply, State, Timeout} |
+%%          {stop, Reason, State}            (terminate/2 is called)
+%%----------------------------------------------------------------------
+handle_cast(Msg, State) ->
+    {noreply, State}.
+
+%%----------------------------------------------------------------------
+%% Func: handle_info/2
+%% Returns: {noreply, State}          |
+%%          {noreply, State, Timeout} |
+%%          {stop, Reason, State}            (terminate/2 is called)
+%%----------------------------------------------------------------------
+handle_info(Info, State) ->
+    {noreply, State}.
+
+%%----------------------------------------------------------------------
+%% Func: terminate/2
+%% Purpose: Shutdown the server
+%% Returns: any (ignored by gen_server)
+%%----------------------------------------------------------------------
+terminate(Reason, State) ->
+    erl_ddll:unload_driver(?DRIVER_NAME),
+    ok.
+
+%%----------------------------------------------------------------------
+%% Func: code_change/3
+%% Purpose: Convert process state when code is changed
+%% Returns: {ok, NewState}
+%%----------------------------------------------------------------------
+code_change(OldVsn, State, Extra) ->
+    {ok, State}.
+
+%%%----------------------------------------------------------------------
+%%% Internal functions
+%%%----------------------------------------------------------------------
+
+%%
+%% Actually load the driver.
+%%
+load_driver() ->
+    Dir = find_priv_lib(),
+    erl_ddll:load_driver(Dir,?DRIVER_NAME).
+
+%%
+%% As this server may be started by the distribution, it is not safe to assume 
+%% a working code server, neither a working file server.
+%% I try to utilize the most primitive interfaces available to determine
+%% the directory of the port_program.
+%%
+find_priv_lib() ->
+    PrivDir = case (catch code:priv_dir(uds_dist)) of
+		  {'EXIT', _} ->
+		      %% Code server probably not startet yet
+		      {ok, P} = erl_prim_loader:get_path(),
+		      ModuleFile = atom_to_list(?MODULE) ++ extension(),
+		      Pd = (catch lists:foldl
+			    (fun(X,Acc) ->
+				     M = filename:join([X, ModuleFile]),
+				     %% The file server probably not started
+				     %% either, has to use raw interface.
+				     case file:raw_read_file_info(M) of 
+					 {ok,_} -> 
+					     %% Found our own module in the
+					     %% path, lets bail out with
+					     %% the priv_dir of this directory
+					     Y = filename:split(X),
+					     throw(filename:join
+						   (lists:sublist
+						    (Y,length(Y) - 1) 
+						    ++ ["priv"])); 
+					 _ -> 
+					     Acc 
+				     end 
+			     end,
+			     false,P)),
+		      case Pd of
+			  false ->
+			      exit(uds_dist_priv_lib_indeterminate);
+			  _ ->
+			      Pd
+		      end;
+		  Dir ->
+		      Dir
+	      end,
+    filename:join([PrivDir, "lib"]).
+
+extension() ->
+    %% erlang:info(machine) returns machine name as text in all uppercase
+    "." ++ lists:map(fun(X) ->
+			     X + $a - $A
+		     end,
+		     erlang:info(machine)).
+