From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001
From: Erlang/OTP <otp@erlang.org>
Date: Fri, 20 Nov 2009 14:54:40 +0000
Subject: The R13B03 release.

---
 lib/kernel/src/user_sup.erl | 129 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 lib/kernel/src/user_sup.erl

(limited to 'lib/kernel/src/user_sup.erl')

diff --git a/lib/kernel/src/user_sup.erl b/lib/kernel/src/user_sup.erl
new file mode 100644
index 0000000000..35b7ff0cfe
--- /dev/null
+++ b/lib/kernel/src/user_sup.erl
@@ -0,0 +1,129 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 1996-2009. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+-module(user_sup).
+
+%% ---------------------------------------------
+%% This is a supervisor bridge hiding the process
+%% details of the user/group implementation.
+%% ---------------------------------------------
+
+-behaviour(supervisor_bridge).
+
+-export([start/0]).
+
+%% Internal exports.
+-export([init/1, terminate/2, relay/1]).
+
+-spec start() -> {'error', {'already_started', pid()}} | {'ok', pid()}.
+
+start() ->
+    supervisor_bridge:start_link(user_sup, []).
+
+-spec init([]) -> 'ignore' | {'error', 'nouser'} | {'ok', pid(), pid()}.
+
+init([]) ->
+    case get_user() of
+	nouser ->
+	    ignore;
+	{master, Master} ->
+	    Pid = start_slave(Master),
+	    {ok, Pid, Pid};
+	{M, F, A} ->
+	    case start_user({M, F}, A) of
+		{ok, Pid} ->
+		    {ok, Pid, Pid};
+		Error ->
+		    Error
+	    end
+    end.
+
+start_slave(Master) ->
+    case rpc:call(Master, erlang, whereis, [user]) of
+	User when is_pid(User) ->
+	    spawn(?MODULE, relay, [User]);
+	_ ->
+	    error_logger:error_msg("Cannot get remote user", []),
+	    receive after 1000 -> true end,
+	    halt()
+    end.
+
+-spec relay(pid()) -> no_return().
+
+relay(Pid) ->
+    register(user, self()),
+    relay1(Pid).
+
+relay1(Pid) ->
+    receive
+        X ->
+            Pid ! X,
+	    relay1(Pid)
+    end.
+
+
+%%-----------------------------------------------------------------
+%% Sleep a while in order to let user write all (some) buffered 
+%% information before termination.
+%%-----------------------------------------------------------------
+
+-spec terminate(term(), pid()) -> 'ok'.
+
+terminate(_Reason, UserPid) ->
+    receive after 1000 -> ok end,
+    exit(UserPid, kill),
+    ok.
+
+%%-----------------------------------------------------------------
+%% If there is a user, wait for it to register itself.  (But wait
+%% no more than 10 seconds).  This is so the application_controller
+%% is guaranteed that the user is started.
+%%-----------------------------------------------------------------
+
+start_user(Func,A) ->
+    apply(Func, A),
+    wait_for_user_p(100).
+
+wait_for_user_p(0) ->
+    {error, nouser};
+wait_for_user_p(N) ->
+    case whereis(user) of
+	Pid when is_pid(Pid) ->
+	    link(Pid),
+	    {ok, Pid};
+	_ ->
+	    receive after 100 -> ok end,
+	    wait_for_user_p(N-1)
+    end.
+
+get_user() ->
+    Flags = init:get_arguments(),
+    check_flags(Flags, {user_drv, start, []}).
+
+%% These flags depend upon what arguments the erl script passes on
+%% to erl91.
+check_flags([{nouser, []} |T], _) -> check_flags(T, nouser);
+check_flags([{user, [User]} | T], _) ->
+    check_flags(T, {list_to_atom(User), start, []});
+check_flags([{noshell, []} | T], _) -> check_flags(T, {user, start, []});
+check_flags([{oldshell, []} | T], _) -> check_flags(T, {user, start, []});
+check_flags([{noinput, []} | T], _) -> check_flags(T, {user, start_out, []});
+check_flags([{master, [Node]} | T], _) ->
+    check_flags(T, {master, list_to_atom(Node)});
+check_flags([_H | T], User) -> check_flags(T, User);
+check_flags([], User) -> User.
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