File 2348-stdlib-Make-gen_fsm-callbacks-optional.patch of Package erlang

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File 2348-stdlib-Make-gen_fsm-callbacks-optional.patch of Package erlang (Revision a3b4c77afbad4ac65be3a89ba1e0ebff)

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From 215f61f223a07493d1147a04375d11f3c7819e42 Mon Sep 17 00:00:00 2001
From: Zandra Norman <zandra@erlang.org>
Date: Tue, 24 Jan 2017 13:40:21 +0100
Subject: [PATCH 3/4] stdlib: Make gen_fsm callbacks optional

---
 lib/stdlib/doc/src/gen_fsm.xml                |  19 ++++
 lib/stdlib/src/gen_fsm.erl                    |  47 +++++---
 lib/stdlib/test/erl_internal_SUITE.erl        |   2 +-
 lib/stdlib/test/gen_fsm_SUITE.erl             | 151 +++++++++++++++++++++++++-
 lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl |  48 ++++++++
 5 files changed, 244 insertions(+), 23 deletions(-)
 create mode 100644 lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl

diff --git a/lib/stdlib/doc/src/gen_fsm.xml b/lib/stdlib/doc/src/gen_fsm.xml
index 719ab2b55..691a039e3 100644
--- a/lib/stdlib/doc/src/gen_fsm.xml
+++ b/lib/stdlib/doc/src/gen_fsm.xml
@@ -562,6 +562,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4
 <v>Extra = term()</v>
 </type>
 <desc>
+ <note>
+ This callback is optional, so callback modules need not export it.
+ If a release upgrade/downgrade with <c>Change={advanced,Extra}</c>
+ specified in the <c>appup</c> file is made when <c>code_change/4</c>
+ isn't implemented the process will crash with an <c>undef</c> exit
+ reason.
+ </note>
 This function is called by a <c>gen_fsm</c> process when it is to
 update its internal state data during a release upgrade/downgrade,
 that is, when instruction <c>{update,Module,Change,...}</c>,
@@ -686,6 +693,13 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4
 <v>&nbsp;Reason = normal | term()</v>
 </type>
 <desc>
+ <note>
+ This callback is optional, so callback modules need not
+ export it. The <c>gen_fsm</c> module provides a default
+ implementation of this function that logs about the unexpected
+ <c>Info</c> message, drops it and returns
+ <c>{next_state, StateName, StateData}</c>.
+ </note>
 This function is called by a <c>gen_fsm</c> process when it receives
 any other message than a synchronous or asynchronous event (or a
 system message).
@@ -899,6 +913,11 @@ gen_fsm:sync_send_all_state_event -----> Module:handle_sync_event/4
 <v>StateData = term()</v>
 </type>
 <desc>
+ <note>
+ This callback is optional, so callback modules need not
+ export it. The <c>gen_fsm</c> module provides a default
+ implementation without cleanup.
+ </note>
 This function is called by a <c>gen_fsm</c> process when it is about
 to terminate. It is to be the opposite of
 <seealso marker="#Module:init/1"><c>Module:init/1</c></seealso>
diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl
index e925a75fe..39a8fd42f 100644
--- a/lib/stdlib/src/gen_fsm.erl
+++ b/lib/stdlib/src/gen_fsm.erl
@@ -169,7 +169,8 @@
 State :: term(),
 Status :: term().
 
--optional_callbacks([format_status/2]).
+-optional_callbacks(
+ [handle_info/3, terminate/3, code_change/4, format_status/2]).
 
 %%% ---------------------------------------------------
 %%% Starts a generic state machine.
@@ -466,6 +467,10 @@ handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time) -> %No debug her
 					 StateName, NStateData, [])),
 	 reply(From, Reply),
 	 exit(R);
+ {'EXIT', {undef, [{Mod, handle_info, [_,_,_], _}|_]}} ->
+ error_logger:warning_msg("** Undefined handle_info in ~p~n"
+ "** Unhandled message: ~p~n", [Mod, Msg]),
+ loop(Parent, Name, StateName, StateData, Mod, infinity, []);
 	{'EXIT', What} ->
 	 terminate(What, Name, Msg, Mod, StateName, StateData, []);
 	Reply ->
@@ -540,24 +545,30 @@ reply(Name, {To, Tag}, Reply, Debug, StateName) ->
 -spec terminate(term(), _, _, atom(), _, _, _) -> no_return().
 
 terminate(Reason, Name, Msg, Mod, StateName, StateData, Debug) ->
- case catch Mod:terminate(Reason, StateName, StateData) of
-	{'EXIT', R} ->
-	 FmtStateData = format_status(terminate, Mod, get(), StateData),
-	 error_info(R, Name, Msg, StateName, FmtStateData, Debug),
-	 exit(R);
-	_ ->
-	 case Reason of
-		normal ->
-		 exit(normal);
-		shutdown ->
-		 exit(shutdown);
- 		{shutdown,_}=Shutdown ->
- 		 exit(Shutdown);
+ case erlang:function_exported(Mod, terminate, 3) of
+	true ->
+	 case catch Mod:terminate(Reason, StateName, StateData) of
+		{'EXIT', R} ->
+		 FmtStateData = format_status(terminate, Mod, get(), StateData),
+		 error_info(R, Name, Msg, StateName, FmtStateData, Debug),
+		 exit(R);
 		_ ->
- FmtStateData = format_status(terminate, Mod, get(), StateData),
-		 error_info(Reason,Name,Msg,StateName,FmtStateData,Debug),
-		 exit(Reason)
-	 end
+		 ok
+	 end;
+	false ->
+	 ok
+ end,
+ case Reason of
+	normal ->
+	 exit(normal);
+	shutdown ->
+	 exit(shutdown);
+ 	{shutdown,_}=Shutdown ->
+ 	 exit(Shutdown);
+	_ ->
+	 FmtStateData1 = format_status(terminate, Mod, get(), StateData),
+	 error_info(Reason,Name,Msg,StateName,FmtStateData1,Debug),
+	 exit(Reason)
 end.
 
 error_info(Reason, Name, Msg, StateName, StateData, Debug) ->
diff --git a/lib/stdlib/test/erl_internal_SUITE.erl b/lib/stdlib/test/erl_internal_SUITE.erl
index c4c4a0408..099f21f90 100644
--- a/lib/stdlib/test/erl_internal_SUITE.erl
+++ b/lib/stdlib/test/erl_internal_SUITE.erl
@@ -99,7 +99,7 @@ optional_callbacks(application) ->
 optional_callbacks(gen_server) ->
 [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}];
 optional_callbacks(gen_fsm) ->
- [{format_status,2}];
+ [{handle_info, 3}, {terminate, 3}, {code_change, 4}, {format_status, 2}];
 optional_callbacks(gen_event) ->
 [{handle_info, 2}, {terminate, 2}, {code_change, 3}, {format_status, 2}];
 optional_callbacks(supervisor_bridge) ->
diff --git a/lib/stdlib/test/gen_fsm_SUITE.erl b/lib/stdlib/test/gen_fsm_SUITE.erl
index d6bb002b5..361680a9b 100644
--- a/lib/stdlib/test/gen_fsm_SUITE.erl
+++ b/lib/stdlib/test/gen_fsm_SUITE.erl
@@ -39,6 +39,11 @@
 	 call_format_status/1, error_format_status/1, terminate_crash_format/1,
 	 get_state/1, replace_state/1]).
 
+-export([undef_handle_event/1, undef_handle_sync_event/1, undef_handle_info/1,
+ undef_init/1, undef_code_change/1, undef_terminate1/1, undef_terminate2/1]).
+
+-export([undef_in_handle_info/1, undef_in_terminate/1]).
+
 -export([hibernate/1,hiber_idle/3,hiber_wakeup/3,hiber_idle/2,hiber_wakeup/2]).
 
 -export([enter_loop/1]).
@@ -48,7 +53,7 @@
 
 %% The gen_fsm behaviour
 -export([init/1, handle_event/3, handle_sync_event/4, terminate/3,
-	 handle_info/3, format_status/2]).
+	 handle_info/3, format_status/2, code_change/4]).
 -export([idle/2,	idle/3,
 	 timeout/2,
 	 wfor_conf/2,	wfor_conf/3,
@@ -63,7 +68,8 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() ->
 [{group, start}, {group, abnormal}, shutdown,
- {group, sys}, hibernate, enter_loop].
+ {group, sys}, hibernate, enter_loop, {group, undef_callbacks},
+ undef_in_handle_info, undef_in_terminate].
 
 groups() ->
 [{start, [],
@@ -74,7 +80,10 @@ groups() ->
 {abnormal, [], [abnormal1, abnormal2]},
 {sys, [],
 [sys1, call_format_status, error_format_status, terminate_crash_format,
- get_state, replace_state]}].
+ get_state, replace_state]},
+ {undef_callbacks, [],
+ [undef_handle_event, undef_handle_sync_event, undef_handle_info,
+ undef_init, undef_code_change, undef_terminate1, undef_terminate2]}].
 
 init_per_suite(Config) ->
 Config.
@@ -82,6 +91,11 @@ init_per_suite(Config) ->
 end_per_suite(_Config) ->
 ok.
 
+init_per_group(undef_callbacks, Config) ->
+ DataDir = ?config(data_dir, Config),
+ Server = filename:join(DataDir, "oc_fsm.erl"),
+ {ok, oc_fsm} = compile:file(Server),
+ Config;
 init_per_group(_GroupName, Config) ->
 Config.
 
@@ -868,6 +882,99 @@ enter_loop(Reg1, Reg2) ->
 	 gen_fsm:enter_loop(?MODULE, [], state0, [])
 end.
 
+%% Start should return an undef error if init isn't implemented
+undef_init(Config) when is_list(Config) ->
+ {error, {undef, [{oc_init_fsm, init, [[]], []}|_]}}
+ = gen_fsm:start(oc_init_fsm, [], []),
+ ok.
+
+%% Test that the server crashes correctly if the handle_event callback is
+%% not exported in the callback module
+undef_handle_event(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ MRef = monitor(process, FSM),
+ gen_fsm:send_all_state_event(FSM, state_name),
+ ok = verify_undef_down(MRef, FSM, oc_fsm, handle_event).
+
+%% Test that the server crashes correctly if the handle_sync_event callback is
+%% not exported in the callback module
+undef_handle_sync_event(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ try
+ gen_fsm:sync_send_all_state_event(FSM, state_name),
+ ct:fail(should_crash)
+ catch exit:{{undef, [{oc_fsm, handle_sync_event, _, _}|_]},_} ->
+ ok
+ end.
+
+%% The fsm should log but not crash if the handle_info callback is
+%% calling an undefined function
+undef_handle_info(Config) when is_list(Config) ->
+ error_logger_forwarder:register(),
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ MRef = monitor(process, FSM),
+ FSM ! hej,
+ receive
+ {'DOWN', MRef, process, FSM, _} ->
+ ct:fail(should_not_crash)
+ after 500 ->
+ ok
+ end,
+ receive
+ {warning_msg, _GroupLeader,
+ {FSM, "** Undefined handle_info in " ++ _, [oc_fsm, hej]}} ->
+ ok;
+ Other ->
+ io:format("Unexpected: ~p", [Other]),
+ ct:fail(failed)
+ end.
+
+%% The upgrade should fail if code_change is expected in the callback module
+%% but not exported, but the fsm should continue with the old code
+undef_code_change(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ {error, {'EXIT', {undef, [{oc_fsm, code_change, [_, _, _, _], _}|_]}}}
+ = fake_upgrade(FSM, oc_fsm),
+ ok.
+
+%% Test the default implementation of terminate with normal reason if the
+%% callback module does not export it
+undef_terminate1(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ MRef = monitor(process, FSM),
+ ok = gen_fsm:stop(FSM),
+ ok = verify_down_reason(MRef, FSM, normal).
+
+%% Test the default implementation of terminate with error reason if the
+%% callback module does not export it
+undef_terminate2(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(oc_fsm, [], []),
+ MRef = monitor(process, FSM),
+ ok = gen_fsm:stop(FSM, {error, test}, infinity),
+ ok = verify_down_reason(MRef, FSM, {error, test}).
+
+%% Test that the server crashes correctly if the handle_info callback is
+%% calling an undefined function
+undef_in_handle_info(Config) when is_list(Config) ->
+ {ok, FSM} = gen_fsm:start(?MODULE, [], []),
+ MRef = monitor(process, FSM),
+ FSM ! {call_undef_fun, {?MODULE, handle_info}},
+ verify_undef_down(MRef, FSM, ?MODULE, handle_info),
+ ok.
+
+%% Test that the server crashes correctly if the terminate callback is
+%% calling an undefined function
+undef_in_terminate(Config) when is_list(Config) ->
+ State = {undef_in_terminate, {?MODULE, terminate}},
+ {ok, FSM} = gen_fsm:start(?MODULE, {state_data, State}, []),
+ try
+ gen_fsm:stop(FSM),
+ ct:fail(failed)
+ catch
+ exit:{undef, [{?MODULE, terminate, _, _}|_]} ->
+ ok
+ end.
+
 %%
 %% Functionality check
 %%
@@ -962,7 +1069,31 @@ do_sync_disconnect(FSM) ->
 yes = gen_fsm:sync_send_event(FSM, disconnect),
 check_state(FSM, idle).
 
+verify_down_reason(MRef, Pid, Reason) ->
+ receive
+ {'DOWN', MRef, process, Pid, Reason} ->
+ ok;
+ {'DOWN', MRef, process, Pid, Other}->
+ ct:fail({wrong_down_reason, Other})
+ after 5000 ->
+ ct:fail(should_shutdown)
+ end.
 
+verify_undef_down(MRef, Pid, Mod, Fun) ->
+ ok = receive
+ {'DOWN', MRef, process, Pid,
+ {undef, [{Mod, Fun, _, _}|_]}} ->
+ ok
+ after 5000 ->
+ ct:fail(should_crash)
+ end.
+
+fake_upgrade(Pid, Mod) ->
+ sys:suspend(Pid),
+ sys:replace_state(Pid, fun(State) -> {new, State} end),
+ Ret = sys:change_code(Pid, Mod, old_vsn, []),
+ ok = sys:resume(Pid),
+ Ret.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%
@@ -992,6 +1123,9 @@ init(_) ->
 
 terminate(_, _State, crash_terminate) ->
 exit({crash, terminate});
+terminate(_, _, {undef_in_terminate, {Mod, Fun}}) ->
+ Mod:Fun(),
+ ok;
 terminate({From, stopped}, State, _Data) ->
 From ! {self(), {stopped, State}},
 ok;
@@ -1089,7 +1223,9 @@ handle_info(hibernate_now, _SName, _State) ->
 {next_state, hiber_idle, [], hibernate};
 handle_info(hibernate_later, _SName, _State) ->
 {next_state, hiber_idle, hibernate_me, 1000};
-
+handle_info({call_undef_fun, {Mod, Fun}}, State, Data) ->
+ Mod:Fun(),
+ {next_state, State, Data};
 handle_info(Info, _State, Data) ->
 {stop, {unexpected,Info}, Data}.
 
@@ -1134,6 +1270,13 @@ format_status(terminate, [_Pdict, StateData]) ->
 format_status(normal, [_Pdict, _StateData]) ->
 [format_status_called].
 
+code_change(_OldVsn, State,
+ {idle, {undef_in_code_change, {Mod, Fun}}} = Data, _Extra) ->
+ Mod:Fun(),
+ {ok, State, Data};
+code_change(_OldVsn, State, Data, _Extra) ->
+ {ok, State, Data}.
+
 get_messages() ->
 receive
 	Msg -> [Msg|get_messages()]
diff --git a/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl b/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl
new file mode 100644
index 000000000..27fb1bc3b
--- /dev/null
+++ b/lib/stdlib/test/gen_fsm_SUITE_data/oc_fsm.erl
@@ -0,0 +1,48 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%% http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(oc_fsm).
+
+-behaviour(gen_fsm).
+
+%% API
+-export([start/0]).
+
+%% gen_fsm callbacks
+-export([init/1,
+ state_name/2,
+ state_name/3]).
+
+-define(SERVER, ?MODULE).
+
+-record(state, {}).
+
+start() ->
+ gen_fsm:start({local, ?SERVER}, ?MODULE, [], []).
+
+init([]) ->
+ {ok, state_name, #state{}}.
+
+state_name(_Event, State) ->
+ {next_state, state_name, State}.
+
+state_name(_Event, _From, State) ->
+ Reply = ok,
+ {reply, Reply, state_name, State}.
+
-- 
2.12.2

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File 2348-stdlib-Make-gen_fsm-callbacks-optional.patch of Package erlang (Revision a3b4c77afbad4ac65be3a89ba1e0ebff)

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