1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
|
%%%----------------------------------------------------------------------
%%% File : ejabberd_hooks.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Manage hooks
%%% Created : 8 Aug 2004 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2021 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%----------------------------------------------------------------------
-module(ejabberd_hooks).
-author('alexey@process-one.net').
-behaviour(gen_server).
%% External exports
-export([start_link/0,
add/3,
add/4,
add/5,
delete/3,
delete/4,
delete/5,
run/2,
run/3,
run_fold/3,
run_fold/4]).
%% gen_server callbacks
-export([init/1,
handle_call/3,
handle_cast/2,
code_change/3,
handle_info/2,
terminate/2]).
-include("logger.hrl").
-include("ejabberd_stacktrace.hrl").
-record(state, {}).
-type hook() :: {Seq :: integer(), Module :: atom(), Function :: atom() | fun()}.
%%%----------------------------------------------------------------------
%%% API
%%%----------------------------------------------------------------------
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
-spec add(atom(), fun(), integer()) -> ok.
%% @doc See add/4.
add(Hook, Function, Seq) when is_function(Function) ->
add(Hook, global, undefined, Function, Seq).
-spec add(atom(), HostOrModule :: binary() | atom(), fun() | atom() , integer()) -> ok.
add(Hook, Host, Function, Seq) when is_function(Function) ->
add(Hook, Host, undefined, Function, Seq);
%% @doc Add a module and function to this hook.
%% The integer sequence is used to sort the calls: low number is called before high number.
add(Hook, Module, Function, Seq) ->
add(Hook, global, Module, Function, Seq).
-spec add(atom(), binary() | global, atom(), atom() | fun(), integer()) -> ok.
add(Hook, Host, Module, Function, Seq) ->
gen_server:call(?MODULE, {add, Hook, Host, Module, Function, Seq}).
-spec delete(atom(), fun(), integer()) -> ok.
%% @doc See del/4.
delete(Hook, Function, Seq) when is_function(Function) ->
delete(Hook, global, undefined, Function, Seq).
-spec delete(atom(), binary() | atom(), atom() | fun(), integer()) -> ok.
delete(Hook, Host, Function, Seq) when is_function(Function) ->
delete(Hook, Host, undefined, Function, Seq);
%% @doc Delete a module and function from this hook.
%% It is important to indicate exactly the same information than when the call was added.
delete(Hook, Module, Function, Seq) ->
delete(Hook, global, Module, Function, Seq).
-spec delete(atom(), binary() | global, atom(), atom() | fun(), integer()) -> ok.
delete(Hook, Host, Module, Function, Seq) ->
gen_server:call(?MODULE, {delete, Hook, Host, Module, Function, Seq}).
-spec run(atom(), list()) -> ok.
%% @doc Run the calls of this hook in order, don't care about function results.
%% If a call returns stop, no more calls are performed.
run(Hook, Args) ->
run(Hook, global, Args).
-spec run(atom(), binary() | global, list()) -> ok.
run(Hook, Host, Args) ->
try ets:lookup(hooks, {Hook, Host}) of
[{_, Ls}] ->
run1(Ls, Hook, Args);
[] ->
ok
catch _:badarg ->
ok
end.
-spec run_fold(atom(), T, list()) -> T.
%% @doc Run the calls of this hook in order.
%% The arguments passed to the function are: [Val | Args].
%% The result of a call is used as Val for the next call.
%% If a call returns 'stop', no more calls are performed.
%% If a call returns {stop, NewVal}, no more calls are performed and NewVal is returned.
run_fold(Hook, Val, Args) ->
run_fold(Hook, global, Val, Args).
-spec run_fold(atom(), binary() | global, T, list()) -> T.
run_fold(Hook, Host, Val, Args) ->
try ets:lookup(hooks, {Hook, Host}) of
[{_, Ls}] ->
run_fold1(Ls, Hook, Val, Args);
[] ->
Val
catch _:badarg ->
Val
end.
%%%----------------------------------------------------------------------
%%% Callback functions from gen_server
%%%----------------------------------------------------------------------
init([]) ->
_ = ets:new(hooks, [named_table, {read_concurrency, true}]),
{ok, #state{}}.
handle_call({add, Hook, Host, Module, Function, Seq}, _From, State) ->
HookFormat = {Seq, Module, Function},
Reply = handle_add(Hook, Host, HookFormat),
{reply, Reply, State};
handle_call({delete, Hook, Host, Module, Function, Seq}, _From, State) ->
HookFormat = {Seq, Module, Function},
Reply = handle_delete(Hook, Host, HookFormat),
{reply, Reply, State};
handle_call(Request, From, State) ->
?WARNING_MSG("Unexpected call from ~p: ~p", [From, Request]),
{noreply, State}.
-spec handle_add(atom(), atom(), hook()) -> ok.
handle_add(Hook, Host, El) ->
case ets:lookup(hooks, {Hook, Host}) of
[{_, Ls}] ->
case lists:member(El, Ls) of
true ->
ok;
false ->
NewLs = lists:merge(Ls, [El]),
ets:insert(hooks, {{Hook, Host}, NewLs}),
ok
end;
[] ->
NewLs = [El],
ets:insert(hooks, {{Hook, Host}, NewLs}),
ok
end.
-spec handle_delete(atom(), atom(), hook()) -> ok.
handle_delete(Hook, Host, El) ->
case ets:lookup(hooks, {Hook, Host}) of
[{_, Ls}] ->
NewLs = lists:delete(El, Ls),
ets:insert(hooks, {{Hook, Host}, NewLs}),
ok;
[] ->
ok
end.
handle_cast(Msg, State) ->
?WARNING_MSG("Unexpected cast: ~p", [Msg]),
{noreply, State}.
handle_info(Info, State) ->
?WARNING_MSG("Unexpected info: ~p", [Info]),
{noreply, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%----------------------------------------------------------------------
%%% Internal functions
%%%----------------------------------------------------------------------
-spec run1([hook()], atom(), list()) -> ok.
run1([], _Hook, _Args) ->
ok;
run1([{_Seq, Module, Function} | Ls], Hook, Args) ->
Res = safe_apply(Hook, Module, Function, Args),
case Res of
'EXIT' ->
run1(Ls, Hook, Args);
stop ->
ok;
_ ->
run1(Ls, Hook, Args)
end.
-spec run_fold1([hook()], atom(), T, list()) -> T.
run_fold1([], _Hook, Val, _Args) ->
Val;
run_fold1([{_Seq, Module, Function} | Ls], Hook, Val, Args) ->
Res = safe_apply(Hook, Module, Function, [Val | Args]),
case Res of
'EXIT' ->
run_fold1(Ls, Hook, Val, Args);
stop ->
Val;
{stop, NewVal} ->
NewVal;
NewVal ->
run_fold1(Ls, Hook, NewVal, Args)
end.
-spec safe_apply(atom(), atom(), atom() | fun(), list()) -> any().
safe_apply(Hook, Module, Function, Args) ->
?DEBUG("Running hook ~p: ~p:~p/~B",
[Hook, Module, Function, length(Args)]),
try if is_function(Function) ->
apply(Function, Args);
true ->
apply(Module, Function, Args)
end
catch ?EX_RULE(E, R, St) when E /= exit; R /= normal ->
Stack = ?EX_STACK(St),
?ERROR_MSG("Hook ~p crashed when running ~p:~p/~p:~n" ++
string:join(
["** ~ts"|
["** Arg " ++ integer_to_list(I) ++ " = ~p"
|| I <- lists:seq(1, length(Args))]],
"~n"),
[Hook, Module, Function, length(Args),
misc:format_exception(2, E, R, Stack)|Args]),
'EXIT'
end.
|
