aboutsummaryrefslogblamecommitdiffstats
path: root/lib/runtime_tools/src/dbg.erl
blob: f0086e8cc73eed88539e76b887421a0b484bc735 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
                   
  
                                                        
  



                                                                      
  


                                                                         
  
















                                                                              
                                                         

























































































































































































































































































































                                                                                








                                                                         

















                                                                                






                                                                     












































                                                                            
                                                                




















































































































                                                                                  
                                                    





































                                                                              
                                            




























































































                                                                                  




                                                                                 























































































































































































































































                                                                                  
                                                                                 






























                                                                                   



                                     
                                                                  

                                        
                                                                



























                                                                                     











































                                                                                                        



















































                                                                                   
                                                 








                                                                   
                                       






























































































































































































































































































































                                                                      











                                                                  















































































































































































































































































































































                                                                                
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1996-2013. 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(dbg).
-export([p/1,p/2,c/3,c/4,i/0,start/0,stop/0,stop_clear/0,tracer/0,
	 tracer/2, tracer/3, get_tracer/0, get_tracer/1, tp/2, tp/3, tp/4, 
	 ctp/0, ctp/1, ctp/2, ctp/3, tpl/2, tpl/3, tpl/4, ctpl/0, ctpl/1, 
	 ctpl/2, ctpl/3, ctpg/0, ctpg/1, ctpg/2, ctpg/3, ltp/0, wtp/1, rtp/1, 
	 dtp/0, dtp/1, n/1, cn/1, ln/0, h/0, h/1]).

-export([trace_port/2, flush_trace_port/0, flush_trace_port/1,
	 trace_port_control/1, trace_port_control/2, trace_client/2, 
	 trace_client/3, stop_trace_client/1]).

-export([transform_flags/1,dhandler/2]).

-export([fun2ms/1]).

%% Local exports
-export([erlang_trace/3,get_info/0,deliver_and_flush/1]).

%% Debug exports
-export([wrap_presort/2, wrap_sort/2, wrap_postsort/1, wrap_sortfix/2,
	 match_front/2, match_rear/2,
	 match_0_9/1]).


%%% Shell callable utility
fun2ms(ShellFun) when is_function(ShellFun) ->
    % Check that this is really a shell fun...
    case erl_eval:fun_data(ShellFun) of
        {fun_data,ImportList,Clauses} ->
            case ms_transform:transform_from_shell(
                   ?MODULE,Clauses,ImportList) of
                {error,[{_,[{_,_,Code}|_]}|_],_} ->
                    io:format("Error: ~s~n",
                              [ms_transform:format_error(Code)]),
                    {error,transform_error};
                Else ->
                    Else
            end;
        false ->
            exit({badarg,{?MODULE,fun2ms,
                          [function,called,with,real,'fun',
                           should,be,transformed,with,
                           parse_transform,'or',called,with,
                           a,'fun',generated,in,the,
                           shell]}})
    end.


%%% Client functions.

%%
%% n(Node) -> {ok, Node} | {error, Reason}
%% Adds Node to the list of traced nodes.
%%
n(Node) when Node =:= node() ->
    {error, cant_add_local_node};
n(Node) ->
    case (catch net_adm:ping(Node)) of
	{'EXIT',_} ->
	    {error, {bad_node, Node}};
	pang ->
	    {error, {nodedown, Node}};
	pong ->
	    req({add_node, Node});
	Other ->
	    {error, Other}
    end.

%%
%% cn(Node) -> ok
%% Remove Node from the list of traced nodes.
%%    
cn(Node) ->
    req({remove_node, Node}).

%%
%% ln() -> ok
%% List traced nodes
%%
ln() ->
    lists:foreach(fun(X) ->
                          io:format("~p~n",[X])
                  end,
                  req(get_nodes)),
    ok.

%%
%% tp/tpl(Module, Pattern) | tp/tpl(Module,Function,Pattern) |
%% tp/tpl(Module,Function,Arity,Pattern) | tp/tpl({M,F,A},Pattern) 
%% -> {ok, [{matched,Node,N}]} | 
%%    {ok, [{matched,Node,N}, {saved,M}]} | 
%%    {ok, [{saved,M}]} | 
%%    {error, Reason}
%% Set trace pattern for function or group of functions.
%%
tp(Module, Function, Pattern) ->
    do_tp({Module, Function, '_'}, Pattern, []).
tp(Module, Function, Arity, Pattern) ->
    do_tp({Module, Function, Arity}, Pattern, []).
tp(Module, Pattern) when is_atom(Module) ->
    do_tp({Module, '_', '_'}, Pattern, []);
tp({_Module, _Function, _Arity} = X, Pattern) ->
    do_tp(X,Pattern,[]).
tpl(Module, Function, Pattern) ->
    do_tp({Module, Function, '_'}, Pattern, [local]).
tpl(Module, Function, Arity, Pattern) ->
    do_tp({Module, Function, Arity}, Pattern, [local]).
tpl(Module, Pattern) when is_atom(Module) ->
    do_tp({Module, '_', '_'}, Pattern, [local]);
tpl({_Module, _Function, _Arity} = X, Pattern) ->
    do_tp(X,Pattern,[local]).
do_tp({_Module, _Function, _Arity} = X, Pattern, Flags)
  when is_integer(Pattern);
       is_atom(Pattern) ->
    case ets:lookup(get_pattern_table(), Pattern) of
	[{_,NPattern}] ->
	    do_tp(X, binary_to_term(NPattern), Flags);
	_ ->
	    {error, unknown_pattern}
    end;
do_tp({Module, _Function, _Arity} = X, Pattern, Flags) when is_list(Pattern) ->
    Nodes = req(get_nodes),
    case Module of
	'_' -> 
	    ok;
	M when is_atom(M) ->
	    %% Try to load M on all nodes
	    lists:foreach(fun(Node) ->
				  rpc:call(Node, M, module_info, [])
			  end,
			  Nodes)
    end,
    case lint_tp(Pattern) of
	{ok,_} ->
	    SaveInfo = case save_pattern(Pattern) of
			   N when is_integer(N), N > 0;  is_atom(N)  ->
			       [{saved, N}];
			   _ ->
			       []
		       end,
	    {ok, do_tp_on_nodes(Nodes, X, Pattern, Flags) ++ SaveInfo};
	Other ->
	    Other
    end.

%% All nodes are handled the same way - also the local node if it is traced
do_tp_on_nodes(Nodes, MFA, P, Flags) ->
    lists:map(fun(Node) ->
		      case rpc:call(Node,erlang,trace_pattern,[MFA,P, Flags]) of
			  N when is_integer(N) ->
			      {matched, Node, N};
			  Else ->
			      {matched, Node, 0, Else}
		      end
	      end,
	      Nodes).

%%
%% ctp/ctpl(Module) | ctp/ctpl(Module,Function) | 
%% ctp/ctpl(Module,Function,Arity) | ctp/ctpl({M,F,A}) ->
%% {ok, [{matched, N}]} | {error, Reason}
%% Clears trace pattern for function or group of functions.
%%
ctp() ->
    do_ctp({'_','_','_'},[]).
ctp(Module, Function) ->
    do_ctp({Module, Function, '_'}, []).
ctp(Module, Function, Arity) ->
    do_ctp({Module, Function, Arity}, []).
ctp(Module) when is_atom(Module) ->
    do_ctp({Module, '_', '_'}, []);
ctp({_Module, _Function, _Arity} = X) ->
    do_ctp(X,[]).
ctpl() ->
    do_ctp({'_', '_', '_'}, [local]).    
ctpl(Module, Function) ->
    do_ctp({Module, Function, '_'}, [local]).
ctpl(Module, Function, Arity) ->
    do_ctp({Module, Function, Arity}, [local]).
ctpl(Module) when is_atom(Module) ->
    do_ctp({Module, '_', '_'}, [local]);
ctpl({_Module, _Function, _Arity} = X) ->
    do_ctp(X,[local]).
ctpg() ->
    do_ctp({'_', '_', '_'}, [global]).
ctpg(Module, Function) ->
    do_ctp({Module, Function, '_'}, [global]).
ctpg(Module, Function, Arity) ->
    do_ctp({Module, Function, Arity}, [global]).
ctpg(Module) when is_atom(Module) ->
    do_ctp({Module, '_', '_'}, [global]);
ctpg({_Module, _Function, _Arity} = X) ->
    do_ctp(X,[global]).
do_ctp({Module, Function, Arity},[]) ->
    do_ctp({Module, Function, Arity},[global]),
    do_ctp({Module, Function, Arity},[local]);
do_ctp({_Module, _Function, _Arity}=MFA,Flags) ->
    Nodes = req(get_nodes),
    {ok,do_tp_on_nodes(Nodes,MFA,false,Flags)}.

%%
%% ltp() -> ok
%% List saved and built-in trace patterns.
%%
ltp() ->
    pt_doforall(fun({X, El},_Ignore) -> 
			io:format("~p: ~p~n", [X,El]) 
		end,[]).

%%
%% dtp() | dtp(N) -> ok
%% Delete saved pattern with number N or all saved patterns
%%
%% Do not delete built-in trace patterns.
dtp() ->
    pt_doforall(fun ({Key, _}, _) when is_integer(Key) ->
			dtp(Key);
		    ({_, _}, _) ->
			ok
		end,
		[]).
dtp(N) when is_integer(N) ->
    ets:delete(get_pattern_table(), N),
    ok;
dtp(_) ->
    ok.

%%
%% wtp(FileName) -> ok | {error, Reason}
%% Writes all current saved trace patterns to a file.
%%
%% Actually write the built-in trace patterns too.
wtp(FileName) ->
    case file:open(FileName,[write]) of
	{error, Reason} ->
	    {error, Reason};
	{ok, File} ->
	    pt_doforall(fun ({_, Val}, _) when is_list(Val) ->
				io:format(File, "~p.~n", [Val]);
			    ({_, _}, _) ->
				ok
			end,
			[]),
	    file:close(File),
	    ok
    end.

%%
%% rtp(FileName) -> ok | {error, Reason}
%% Reads in previously saved pattern file and merges the contents
%% with what's there now.
%%
%% So the saved built-in trace patterns will merge with
%% the already existing, which should be the same.
rtp(FileName) ->
    T = get_pattern_table(),
    case file:consult(FileName) of
	{error, Reason1} ->
	    {error, {read_error, Reason1}};
	{ok, Data} ->
	    case check_list(Data) of
		ok ->
		    lists:foreach(fun(X) ->
					  save_pattern(X,T)
				  end, Data),
		    ok;
		{error, Reason2} ->
		    {error, {file_format_error, Reason2}}
	    end
    end.

tracer() ->
    tracer(process, {fun dhandler/2,user}).

tracer(port, Fun) when is_function(Fun) ->
    start(Fun);

tracer(port, Port) when is_port(Port) ->
    start(fun() -> Port end);

tracer(process, {Handler,HandlerData}) ->
    start(fun() -> start_tracer_process(Handler, HandlerData) end).


remote_tracer(port, Fun) when is_function(Fun) ->
    remote_start(Fun);

remote_tracer(port, Port) when is_port(Port) ->
    remote_start(fun() -> Port end);

remote_tracer(process, {Handler,HandlerData}) ->
    remote_start(fun() -> start_tracer_process(Handler, HandlerData) end).

remote_start(StartTracer) ->
    case (catch StartTracer()) of
	{'EXIT', Reason} ->
	    {error, Reason};
	Tracer ->
	    {ok,Tracer}
    end.

%%
%% tracer(Node,Type,Data) -> {ok, Node} | {error, Reason}
%% Add Node to the list of traced nodes and a trace port defined by
%% Type and Data is started on Node.
%%
tracer(Node,Type,Data) when Node =:= node() ->
    case tracer(Type,Data) of
	{ok,_Dbg} -> {ok,Node};
	Error -> Error
    end;
tracer(Node,Type,Data) ->
    case (catch net_adm:ping(Node)) of
	{'EXIT',_} ->
	    {error, {bad_node, Node}};
	pang ->
	    {error, {nodedown, Node}};
	pong ->
	    req({add_node, Node, Type, Data});
	Other ->
	    {error, Other}
    end.

flush_trace_port() ->
    trace_port_control(flush).
flush_trace_port(Node) ->
    trace_port_control(Node, flush).

trace_port_control(Operation) ->
    trace_port_control(node(), Operation).

trace_port_control(Node, flush) ->
    case get_tracer(Node) of
	{ok, Port} when is_port(Port) ->
	    case catch rpc:call(Node,?MODULE,deliver_and_flush,[Port]) of
		[0] ->
		    ok;
		_ ->
		    {error, not_supported_by_trace_driver}
	    end;
	_ ->
	    {error, no_trace_driver}
    end;
trace_port_control(Node,get_listen_port) ->
    case trace_port_control(Node,$p, "") of
	{ok, <<0, IpPort:16>>} ->
	    {ok, IpPort};
	{ok, _Other} ->
	    {error, not_supported_by_trace_driver};
	Other ->
	    Other
    end.

trace_port_control(Node, Command, Arg) ->
    case get_tracer(Node) of
	{ok, Port} when is_port(Port) ->
	    {ok, catch rpc:call(Node,erlang,port_control,[Port, Command, Arg])};
	_ ->
	    {error, no_trace_driver}
    end.
    
%% A bit more than just flush - it also makes sure all trace messages
%% are delivered first, before flushing the driver.
deliver_and_flush(Port) ->
    Ref = erlang:trace_delivered(all),
    receive
	{trace_delivered,all,Ref} -> ok
    end,
    erlang:port_control(Port, $f, "").
					   

trace_port(file, {Filename, wrap, Tail}) ->
    trace_port(file, {Filename, wrap, Tail, 128*1024});
trace_port(file, {Filename, wrap, Tail, WrapSize}) ->
    trace_port(file, {Filename, wrap, Tail, WrapSize, 8});
trace_port(file, {Filename, wrap, Tail, WrapSize, WrapCnt})
  when is_list(Tail), 
       is_integer(WrapSize), WrapSize >= 0, WrapSize < (1 bsl 32),
       is_integer(WrapCnt), WrapCnt >= 1, WrapCnt < (1 bsl 32) ->
    trace_port1(file, Filename, {wrap, Tail, WrapSize, WrapCnt, 0});
trace_port(file, {Filename, wrap, Tail, {time, WrapTime}, WrapCnt})
  when is_list(Tail), 
       is_integer(WrapTime), WrapTime >= 1, WrapTime < (1 bsl 32),
       is_integer(WrapCnt), WrapCnt >= 1, WrapCnt < (1 bsl 32) ->
    trace_port1(file, Filename, {wrap, Tail, 0, WrapCnt, WrapTime});
trace_port(file, Filename) ->
    trace_port1(file, Filename, nowrap);

trace_port(ip, Portno) when is_integer(Portno) -> 
    trace_port(ip,{Portno,50});

trace_port(ip, {Portno, Qsiz}) when is_integer(Portno), is_integer(Qsiz) -> 
    fun() ->
	    Driver = "trace_ip_drv",
	    Dir1 = filename:join(code:priv_dir(runtime_tools), "lib"),
	    case catch erl_ddll:load_driver(Dir1, Driver) of
		ok ->
		    ok;
		_ ->
		    Dir2 = filename:join(
			     Dir1, 
			     erlang:system_info(system_architecture)),
		    catch erl_ddll:load_driver(Dir2, Driver)
	    end,
	    L = lists:flatten(
		  io_lib:format("~s ~p ~p 2",
				[Driver, Portno, Qsiz])),
	    open_port({spawn, L}, [eof])
    end.

trace_port1(file, Filename, Options) ->
    Driver = "trace_file_drv",
    fun() ->
	    Name = filename:absname(Filename), 
	    %% Absname is needed since the driver uses 
	    %% the supplied name without further investigations.

	    %% Also, the absname must be found inside the fun,
	    %% in case the actual node where the port shall be
	    %% started is on another node (or even another host)
	    {Wrap, Tail} =
		case Options of
		    {wrap, T, WrapSize, WrapCnt, WrapTime} ->
			{lists:flatten(
			   io_lib:format("w ~p ~p ~p ~p ", 
					 [WrapSize, WrapCnt, WrapTime, 
					  length(Name)])),
			 T};
		    nowrap ->
			{"", ""}
		end,
	    Command = Driver ++ " " ++ Wrap ++ "n " ++ Name ++ Tail,
	    Dir1 = filename:join(code:priv_dir(runtime_tools), "lib"),
	    case catch erl_ddll:load_driver(Dir1, Driver) of
		ok ->
		    ok;
		_ ->
		    Dir2 = filename:join(
			     Dir1, 
			     erlang:system_info(system_architecture)),
		    catch erl_ddll:load_driver(Dir2, Driver)
	    end,
	    if 	element(1, Options) == wrap ->
		    %% Delete all files from any previous wrap log
		    Files = wrap_postsort(wrap_presort(Name, Tail)),
		    lists:foreach(
		      fun(N) -> file:delete(N) end,
		      Files);
		true -> ok
	    end,
	    open_port({spawn, Command}, [eof])
    end.


trace_client(file, Filename) ->
    trace_client(file, Filename, {fun dhandler/2,user});
trace_client(follow_file, Filename) ->
    trace_client(follow_file, Filename, {fun dhandler/2,user});
trace_client(ip, Portno) when is_integer(Portno) ->
    trace_client1(ip, {"localhost", Portno}, {fun dhandler/2,user});
trace_client(ip, {Host, Portno}) when is_integer(Portno) ->
    trace_client1(ip, {Host, Portno}, {fun dhandler/2,user}).

trace_client(file, {Filename, wrap, Tail}, FD) ->
    trace_client(file, {Filename, wrap, Tail, 128*1024}, FD);
trace_client(file, {Filename, wrap, Tail, WrapSize}, FD) ->
    trace_client(file, {Filename, wrap, Tail, WrapSize, 8}, FD);
trace_client(file, 
	     {_Filename, wrap, Tail, _WrapSize, WrapCnt} = WrapSpec, 
	     {Fun, _Data} = FD)
  when is_list(Tail), is_function(Fun), is_integer(WrapCnt), WrapCnt >= 1 ->
    trace_client1(file, WrapSpec, FD);
trace_client(file, Filename, {Fun, Data} ) when is_function(Fun) ->
    trace_client1(file, Filename, {Fun, Data});
trace_client(follow_file, Filename, {Fun, Data} ) when is_function(Fun) ->
    trace_client1(follow_file, Filename, {Fun, Data});
trace_client(ip, Portno, {Fun, Data}) when is_integer(Portno), is_function(Fun) ->
    trace_client1(ip, {"localhost", Portno}, {Fun, Data});
trace_client(ip, {Host, Portno}, {Fun, Data}) when is_integer(Portno), 
						   is_function(Fun) ->
    trace_client1(ip, {Host, Portno}, {Fun, Data}).

trace_client1(Type, OpenData, {Handler,HData}) ->
    case req({link_to, 
	      spawn(
		fun() ->
			tc_loop(gen_reader(Type, OpenData), Handler, HData)
		end)}) of
	{ok, Pid} ->
	    Pid;
	Other ->
	    Other
    end.

stop_trace_client(Pid) when is_pid(Pid) ->
    process_flag(trap_exit,true),
    link(Pid),
    exit(to_pidspec(Pid),abnormal),
    Res = receive 
	      {'EXIT', Pid, _} ->
		  ok
	  after 5000 ->
		  {error, timeout}
	  end,
    process_flag(trap_exit,false),
    Res.

p(Pid) ->
    p(Pid, [m]).

p(Pid, Flags) when is_atom(Flags) ->
    p(Pid, [Flags]);
p(Pid, Flags) ->
    req({p,Pid,Flags}).

i() -> req(i).
	
c(M, F, A) ->
    c(M, F, A, all).
c(M, F, A, Flags) when is_atom(Flags) ->
    c(M, F, A, [Flags]);
c(M, F, A, Flags) ->
    case transform_flags(Flags) of
	{error,Reason} -> {error,Reason};
	Flags1 ->
	    tracer(),
	    {ok, Tracer} = get_tracer(),
	    S = self(),
	    Pid = spawn(fun() -> c(S, M, F, A, [{tracer, Tracer} | Flags1]) end),
	    Mref = erlang:monitor(process, Pid),
	    receive
		{'DOWN', Mref, _, _, Reason} ->
		    stop_clear(),
		    {error, Reason};
		{Pid, Res} ->
		    erlang:demonitor(Mref, [flush]),
		    %% 'sleep' prevents the tracer (recv_all_traces) from
		    %% receiving garbage {'EXIT',...} when dbg i stopped.
		    timer:sleep(1),
		    stop_clear(),
		    Res
	    end
    end.

c(Parent, M, F, A, Flags) ->
    %% The trace BIF is used directly here instead of the existing function
    %% p/2. The reason is that p/2 (when stopping trace) sends messages which 
    %% we don't want to show up in this simple tracing from the shell.
    erlang:trace(self(), true, Flags),
    Res = apply(M, F, A),
    erlang:trace(self(), false, [all]),
    Parent ! {self(), Res}.

stop() ->
    Mref = erlang:monitor(process, dbg),
    catch dbg ! {self(),stop},
    receive
	{'DOWN',Mref,_,_,_} ->
	    ok
    end.

stop_clear() ->
    ctp(),
    stop().

%%% Calling the server.

req(R) ->
    P = ensure(), % The pid or perhaps the name of the server
    Mref = erlang:monitor(process, P),
    catch P ! {self(), R}, % May crash if P = atom() and server died
    receive
	{'DOWN', Mref, _, _, _} -> % If server died
	    exit(dbg_server_crash);
	{dbg, Reply} ->
	    erlang:demonitor(Mref, [flush]),
	    Reply
    end.

%% Returns the pid of the dbg server, or in worst case the name.
%% Starts a new server if necessary.
ensure() ->
    case whereis(dbg) of
	undefined -> 
	    case start() of
		{ok, P} ->
		    P;
		{error, already_started} ->
		    dbg
	    end;
	Pid -> 
	    Pid
    end.


%%% Server implementation.
start() ->
    start(no_tracer).

start(TracerFun) ->
    S = self(),
    case whereis(dbg) of
	undefined ->
	    Dbg = spawn(fun() -> init(S) end),
	    receive {Dbg,started} -> ok end,
	    case TracerFun of
		no_tracer ->
		    {ok, Dbg};
		Fun when is_function(Fun) ->
		    req({tracer,TracerFun})
	    end;
	Pid when is_pid(Pid), is_function(TracerFun) ->
	    req({tracer,TracerFun})
    end.

init(Parent) ->
    process_flag(trap_exit, true),
    register(dbg, self()),
    Parent ! {self(),started},
    loop({[],[]},[]).

%
% SurviveLinks = Processes we should take with us while falling, 
%                but not get killed by if they die (i. e. trace clients 
%                and relay processes on other nodes)
%                SurviveLinks = {TraceClients,Relays}
%
loop({C,T}=SurviveLinks, Table) ->
    receive
	{From,i} ->
	    reply(From, display_info(lists:map(fun({N,_}) -> N end,get()))),
	    loop(SurviveLinks, Table);
	{From,{p,Pid,Flags}} ->
	    reply(From, trace_process(Pid, Flags)),
	    loop(SurviveLinks, Table);
	{From,{tracer,TracerFun}} when is_function(TracerFun) ->
	    case get(node()) of
		undefined ->
		    case (catch TracerFun()) of
			{'EXIT', Reason} ->
			    reply(From, {error, Reason});
			Tracer when is_pid(Tracer); is_port(Tracer) ->
			    put(node(),{self(),Tracer}),
			    reply(From, {ok,self()})
		    end;
		{_Relay,_Tracer} ->
		    reply(From, {error, already_started})
	    end,
	    loop(SurviveLinks,Table);
	{From,{get_tracer,Node}} ->
	    case get(Node) of
		undefined -> reply(From,{error, {no_tracer_on_node,Node}});
		{_Relay,Tracer} -> reply(From, {ok,Tracer})
	    end,
	    loop(SurviveLinks, Table);
	{From, get_table} ->
	    Tab = case Table of
		      [] ->
			  new_pattern_table();
		      _exists ->
			  Table
		  end,
	    reply(From, {ok, Tab}),
	    loop(SurviveLinks, Tab);
	{_From,stop} ->
	    %% We want to make sure that all trace messages have been delivered
	    %% on all nodes that might be traced. Since dbg:cn/1 does not turn off
	    %% tracing on the node it removes from the list of active trace nodes,
	    %% we will call erlang:trace_delivered/1 on ALL nodes that we have
	    %% connections to.
	    %% If it is a file trace driver, we will also flush the port.
	    lists:foreach(fun({Node,{_Relay,Port}}) ->
				  rpc:call(Node,?MODULE,deliver_and_flush,[Port])
			  end,
			  get()),
	    exit(done);
	{From, {link_to, Pid}} -> 	    
	    case (catch link(Pid)) of
		{'EXIT', Reason} ->
		    reply(From, {error, Reason}),
		    loop(SurviveLinks, Table);
		_ ->
		    reply(From, {ok, Pid}),
		    loop({[Pid|C],T}, Table)
	    end;
	{From, {add_node, Node}} ->
	    case get(node()) of
		undefined -> 
		    reply(From, {error, no_local_tracer}),
		    loop(SurviveLinks, Table);
		{_LocalRelay,Tracer} when is_port(Tracer) -> 
		    reply(From, {error, cant_trace_remote_pid_to_local_port}),
		    loop(SurviveLinks, Table);
	        {_LocalRelay,Tracer} when is_pid(Tracer) ->
		    case (catch relay(Node, Tracer)) of
			{ok,Relay} ->
			    reply(From, {ok, Node}),
			    loop({C,[Relay|T]}, Table);
			{'EXIT', Something} ->
			    reply(From, {error, Something}),
			    loop(SurviveLinks, Table);
			Error ->
			    reply(From, Error),
			    loop(SurviveLinks, Table)
		    end
	    end;
	{From, {add_node, Node, Type, Data}} ->
	    case (catch relay(Node, {Type,Data})) of
		{ok,Relay} ->
		    reply(From, {ok, Node}),
		    loop({C,[Relay|T]}, Table);
		{'EXIT', Something} ->
		    reply(From, {error, Something}),
		    loop(SurviveLinks, Table);
		Error ->
		    reply(From, Error),
		    loop(SurviveLinks, Table)
	    end;
	{From, {remove_node, Node}} ->
	    erase(Node),
	    reply(From, ok),
	    loop(SurviveLinks, Table);
	{From, get_nodes} ->
	    reply(From, lists:map(fun({N,_}) -> N end, get())),
	    loop(SurviveLinks, Table);
	{'EXIT', Pid, Reason} ->
	    case lists:delete(Pid, C) of
		C ->
		    case lists:delete(Pid,T) of
			T ->
			    io:format(user,"** dbg got EXIT - terminating: ~p~n",
				      [Reason]),
			    exit(done);
			NewT -> 
			    erase(node(Pid)),
			    loop({C,NewT}, Table)
		    end;
		NewC ->
		    loop({NewC,T}, Table)
	    end;
	Other ->
	    io:format(user,"** dbg got garbage: ~p~n", 
		      [{Other,SurviveLinks,Table}]),
	    loop(SurviveLinks, Table)
    end.

reply(Pid, Reply) ->
    Pid ! {dbg,Reply}.


%%% A process-based tracer.

start_tracer_process(Handler, HandlerData) ->
    spawn_opt(fun() -> tracer_init(Handler, HandlerData) end,
	      [link,{priority,max}]).
    

tracer_init(Handler, HandlerData) ->
    process_flag(trap_exit, true),
    tracer_loop(Handler, HandlerData).

tracer_loop(Handler, Hdata) ->
    receive
	Msg ->
	    %% Don't match in receive to avoid giving EXIT message higher
	    %% priority than the trace messages.
	    case Msg of
		{'EXIT',_Pid,_Reason} ->
		    ok;
		Trace ->
		    NewData = recv_all_traces(Trace, Handler, Hdata),
		    tracer_loop(Handler, NewData)
	    end
    end.
    
recv_all_traces(Trace, Handler, Hdata) ->
    Suspended = suspend(Trace, []),
    recv_all_traces(Suspended, Handler, Hdata, [Trace]).

recv_all_traces(Suspended0, Handler, Hdata, Traces) ->
    receive
	Trace when is_tuple(Trace), element(1, Trace) == trace ->
	    Suspended = suspend(Trace, Suspended0),
	    recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
	Trace when is_tuple(Trace), element(1, Trace) == trace_ts ->
	    Suspended = suspend(Trace, Suspended0),
	    recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
	Trace when is_tuple(Trace), element(1, Trace) == seq_trace ->
	    Suspended = suspend(Trace, Suspended0),
	    recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
	Trace when is_tuple(Trace), element(1, Trace) == drop ->
	    Suspended = suspend(Trace, Suspended0),
	    recv_all_traces(Suspended, Handler, Hdata, [Trace|Traces]);
	Other ->
	    %%% Is this really a good idea?
	    io:format(user,"** tracer received garbage: ~p~n", [Other]),
	    recv_all_traces(Suspended0, Handler, Hdata, Traces)
    after 0 ->
	    case catch invoke_handler(Traces, Handler, Hdata) of
		{'EXIT',Reason} -> 
		    resume(Suspended0),
		    exit({trace_handler_crashed,Reason});
		NewHdata ->
		    resume(Suspended0),
		    NewHdata
	    end
    end.

invoke_handler([Tr|Traces], Handler, Hdata0) ->
    Hdata = invoke_handler(Traces, Handler, Hdata0),
    Handler(Tr, Hdata);
invoke_handler([], _Handler, Hdata) ->
    Hdata.

suspend({trace,From,call,_Func}, Suspended) when node(From) == node() ->
    case (catch erlang:suspend_process(From, [unless_suspending,
					      asynchronous])) of
	true ->
	    [From | Suspended];
	_ ->
	    Suspended
    end;
suspend(_Other, Suspended) -> Suspended.

resume([Pid|Pids]) when node(Pid) == node() ->
    (catch erlang:resume_process(Pid)),
    resume(Pids);
resume([]) -> ok.



%%% Utilities.

trac(Proc, How, Flags) when is_atom(Proc) ->
    %% Proc = all | new | existing | RegisteredName
    %% Must go to all nodes
    case get() of
	[] ->
	    {error,no_tracers};
	Nodes ->
	    Matched = [trac(Node, NodeInfo, Proc, How, Flags)
		       || {Node, NodeInfo} <- Nodes],
	    {ok,Matched}
    end;
trac(Proc, How, Flags) ->
    %% Proc = Pid | Integer | {X,Y,Z} | "<X.Y.Z>"
    %% One node only
    Pid = to_pid(Proc),
    case Pid of
	{badpid,_} ->
	    {error,Pid};
	_ ->
	    Node = if is_pid(Pid) -> node(Pid); true -> node() end,
	    case get(Node) of
		undefined ->
		    {error,{no_tracer_on_node,Node}};
		NodeInfo ->
		    Match = trac(Node, NodeInfo, Pid, How, Flags),
		    {ok,[Match]}
	    end
    end.

trac(Node, {_Relay, Tracer}, AtomPid, How, Flags) ->
    case rpc:call(Node, ?MODULE, erlang_trace,
		  [AtomPid, How, [{tracer, Tracer} | Flags]]) of
	N when is_integer(N) ->
	    {matched, Node, N};
	{badrpc,Reason} ->
	    {matched, Node, 0, Reason};
	Else ->
	    {matched, Node, 0, Else}
    end.

erlang_trace(AtomPid, How, Flags) ->
    case to_pidspec(AtomPid) of
	{badpid,_} ->
	    {no_proc,AtomPid};
	P ->
	    erlang:trace(P, How, Flags)
    end.

%% Since we are not allowed to do erlang:trace/3 on a remote
%% process, we create a relay process at the remote node.

relay(Node,To) when Node /= node() ->
    case get(Node) of
	undefined -> 
	    S = self(),
	    Pid = spawn_link(Node, fun() -> do_relay(S,To) end),
	    receive {started,Remote} -> put(Node, {Pid,Remote}) end,
	    {ok,Pid};
	{_Relay,PortOrPid} ->
	    {error, {already_started, PortOrPid}}
    end.

do_relay(Parent,RelP) ->
    process_flag(trap_exit, true),
    case RelP of
	{Type,Data} -> 
	    {ok,Tracer} = remote_tracer(Type,Data),
	    Parent ! {started,Tracer};
	Pid when is_pid(Pid) ->
	    Parent ! {started,self()}
    end,
    do_relay_1(RelP).

do_relay_1(RelP) ->
    %% In the case of a port tracer, this process exists only so that
    %% dbg know that the node is alive... should maybe use monitor instead?
    receive
	{'EXIT', _P, _} ->
	    exit(normal);
	TraceInfo when is_pid(RelP) ->  % Here is the normal case for trace i/o
	    RelP ! TraceInfo, 
	    do_relay_1(RelP);
	Other ->
	    io:format(user,"** relay got garbage: ~p~n", [Other]),
	    do_relay_1(RelP)
    end.

dhandler(end_of_trace, Out) ->
    Out;
dhandler(Trace, Out) when element(1, Trace) == trace, tuple_size(Trace) >= 3 ->
    dhandler1(Trace, tuple_size(Trace), Out);
dhandler(Trace, Out) when element(1, Trace) == trace_ts, tuple_size(Trace) >= 4 ->
    dhandler1(Trace, tuple_size(Trace)-1, element(tuple_size(Trace),Trace), Out);
dhandler(Trace, Out) when element(1, Trace) == drop, tuple_size(Trace) =:= 2 ->
    io:format(Out, "*** Dropped ~p messages.~n", [element(2,Trace)]),
    Out;
dhandler(Trace, Out) when element(1, Trace) == seq_trace, tuple_size(Trace) >= 3 ->
    SeqTraceInfo = case Trace of
		       {seq_trace, Lbl, STI, TS} ->
			   io:format(Out, "SeqTrace ~p [~p]: ",
				     [TS, Lbl]),
			   STI;
		       {seq_trace, Lbl, STI} ->
			  io:format(Out, "SeqTrace [~p]: ",
				     [Lbl]),
			   STI 
		   end,
    case SeqTraceInfo of
	{send, Ser, Fr, To, Mes} ->
	    io:format(Out, "(~p) ~p ! ~p [Serial: ~p]~n",
		      [Fr, To, Mes, Ser]);
	{'receive', Ser, Fr, To, Mes} ->
	    io:format(Out, "(~p) << ~p [Serial: ~p, From: ~p]~n",
		      [To, Mes, Ser, Fr]);
	{print, Ser, Fr, _, Info} ->
	    io:format(Out, "-> ~p [Serial: ~p, From: ~p]~n",
		      [Info, Ser, Fr]);
	Else ->
	    io:format(Out, "~p~n", [Else])
    end,
    Out;
dhandler(_Trace, Out) ->
    Out.

dhandler1(Trace, Size, Out) ->
    From = element(2, Trace),
    case element(3, Trace) of
	'receive' ->
	    case element(4, Trace) of
		{dbg,ok} -> ok;
		Message ->
		    io:format(Out, "(~p) << ~p~n", [From,Message])
	    end;
	'send' ->
	    Message = element(4, Trace),
	    To = element(5, Trace),
	    io:format(Out, "(~p) ~p ! ~p~n", [From,To,Message]);
	call ->
	    case element(4, Trace) of
		MFA when Size == 5 ->
		    Message = element(5, Trace),
		    io:format(Out, "(~p) call ~s (~p)~n", [From,ffunc(MFA),Message]);
		MFA ->
		    io:format(Out, "(~p) call ~s~n", [From,ffunc(MFA)])
	    end;
	return -> %% To be deleted...
	    case element(4, Trace) of
		MFA when Size == 5 ->
		    Ret = element(5, Trace),
		    io:format(Out, "(~p) old_ret ~s -> ~p~n", [From,ffunc(MFA),Ret]);
		MFA ->
		    io:format(Out, "(~p) old_ret ~s~n", [From,ffunc(MFA)])
	    end;
	return_from ->
	    MFA = element(4, Trace),
	    Ret = element(5, Trace),
	    io:format(Out, "(~p) returned from ~s -> ~p~n", [From,ffunc(MFA),Ret]);
	return_to ->
	    MFA = element(4, Trace),
	    io:format(Out, "(~p) returning to ~s~n", [From,ffunc(MFA)]);
	spawn when Size == 5 ->
	    Pid = element(4, Trace),
	    MFA = element(5, Trace),
	    io:format(Out, "(~p) spawn ~p as ~s~n", [From,Pid,ffunc(MFA)]);
	Op ->
	    io:format(Out, "(~p) ~p ~s~n", [From,Op,ftup(Trace,4,Size)])
    end,
    Out.

dhandler1(Trace, Size, TS, Out) ->
    From = element(2, Trace),
    case element(3, Trace) of
	'receive' ->
	    case element(4, Trace) of
		{dbg,ok} -> ok;
		Message ->
		    io:format(Out, "(~p) << ~p (Timestamp: ~p)~n", [From,Message,TS])
	    end;
	'send' ->
	    Message = element(4, Trace),
	    To = element(5, Trace),
	    io:format(Out, "(~p) ~p ! ~p (Timestamp: ~p)~n", [From,To,Message,TS]);
	call ->
	    case element(4, Trace) of
		MFA when Size == 5 ->
		    Message = element(5, Trace),
		    io:format(Out, "(~p) call ~s (~p) (Timestamp: ~p)~n", [From,ffunc(MFA),Message,TS]);
		MFA ->
		    io:format(Out, "(~p) call ~s (Timestamp: ~p)~n", [From,ffunc(MFA),TS])
	    end;
	return -> %% To be deleted...
	    case element(4, Trace) of
		MFA when Size == 5 ->
		    Ret = element(5, Trace),
		    io:format(Out, "(~p) old_ret ~s -> ~p (Timestamp: ~p)~n", [From,ffunc(MFA),Ret,TS]);
		MFA ->
		    io:format(Out, "(~p) old_ret ~s (Timestamp: ~p)~n", [From,ffunc(MFA),TS])
	    end;
	return_from ->
	    MFA = element(4, Trace),
	    Ret = element(5, Trace),
	    io:format(Out, "(~p) returned from ~s -> ~p (Timestamp: ~p)~n", [From,ffunc(MFA),Ret,TS]);
	return_to ->
	    MFA = element(4, Trace),
	    io:format(Out, "(~p) returning to ~s (Timestamp: ~p)~n", [From,ffunc(MFA),TS]);
	spawn when Size == 5 ->
	    Pid = element(4, Trace),
	    MFA = element(5, Trace),
	    io:format(Out, "(~p) spawn ~p as ~s (Timestamp: ~p)~n", [From,Pid,ffunc(MFA),TS]);
	Op ->
	    io:format(Out, "(~p) ~p ~s (Timestamp: ~p)~n", [From,Op,ftup(Trace,4,Size),TS])
    end,
    Out.



%%% These f* functions returns non-flat strings

%% {M,F,[A1, A2, ..., AN]} -> "M:F(A1, A2, ..., AN)"
%% {M,F,A}                 -> "M:F/A"
ffunc({M,F,Argl}) when is_list(Argl) ->
    io_lib:format("~p:~p(~s)", [M, F, fargs(Argl)]);
ffunc({M,F,Arity}) ->
    io_lib:format("~p:~p/~p", [M,F,Arity]);
ffunc(X) -> io_lib:format("~p", [X]).

%% Integer           -> "Integer"
%% [A1, A2, ..., AN] -> "A1, A2, ..., AN"
fargs(Arity) when is_integer(Arity) -> integer_to_list(Arity);
fargs([]) -> [];
fargs([A]) -> io_lib:format("~p", [A]);  %% last arg
fargs([A|Args]) -> [io_lib:format("~p,", [A]) | fargs(Args)];
fargs(A) -> io_lib:format("~p", [A]). % last or only arg

%% {A_1, A_2, ..., A_N} -> "A_Index A_Index+1 ... A_Size"
ftup(Trace, Index, Index) -> 
    io_lib:format("~p", [element(Index, Trace)]);
ftup(Trace, Index, Size) -> 
    [io_lib:format("~p ", [element(Index, Trace)]) 
     | ftup(Trace, Index+1, Size)].



trace_process(Pid, [clear]) ->
    trac(Pid, false, all());
trace_process(Pid, Flags0) ->
    case transform_flags(Flags0) of
	{error,Reason} -> {error,Reason};
	Flags -> trac(Pid, true, Flags)
    end.

transform_flags(Flags0) ->
    transform_flags(Flags0,[]).
transform_flags([],Acc) -> Acc;
transform_flags([m|Tail],Acc) -> transform_flags(Tail,[send,'receive'|Acc]);
transform_flags([s|Tail],Acc) -> transform_flags(Tail,[send|Acc]);
transform_flags([r|Tail],Acc) -> transform_flags(Tail,['receive'|Acc]);
transform_flags([c|Tail],Acc) -> transform_flags(Tail,[call|Acc]);
transform_flags([call|Tail],Acc) -> transform_flags(Tail,[call|Acc]);
transform_flags([p|Tail],Acc) -> transform_flags(Tail,[procs|Acc]);
transform_flags([sos|Tail],Acc) -> transform_flags(Tail,[set_on_spawn|Acc]);
transform_flags([sol|Tail],Acc) -> transform_flags(Tail,[set_on_link|Acc]);
transform_flags([sofs|Tail],Acc) -> transform_flags(Tail,[set_on_first_spawn|Acc]);
transform_flags([sofl|Tail],Acc) -> transform_flags(Tail,[set_on_first_link|Acc]);
transform_flags([all|_],_Acc) -> all()--[silent];
transform_flags([F|Tail]=List,Acc) when is_atom(F) ->
    case lists:member(F, all()) of
	true -> transform_flags(Tail,[F|Acc]);
	false -> {error,{bad_flags,List}}
    end;
transform_flags(Bad,_Acc) -> {error,{bad_flags,Bad}}.

all() ->
    [send,'receive',call,procs,garbage_collection,running,
     set_on_spawn,set_on_first_spawn,set_on_link,set_on_first_link,
     timestamp,arity,return_to,silent].

display_info([Node|Nodes]) ->
    io:format("~nNode ~w:~n",[Node]),
    io:format("~-12s ~-21s Trace ~n", ["Pid", "Initial call"]),
    List = rpc:call(Node,?MODULE,get_info,[]),
    display_info1(List),
    display_info(Nodes);
display_info([]) ->
    ok.

display_info1([{Pid,Call,Flags}|T]) ->
    io:format("~-12s ~-21s ~s~n",
	      [io_lib:format("~w",[Pid]),
	       io_lib:format("~p", [Call]),
	       format_trace(Flags)]),
    display_info1(T); 
display_info1([]) ->
    ok.

get_info() ->
    get_info(processes(),[]).

get_info([Pid|T],Acc) ->
    case pinfo(Pid, initial_call) of
        undefined ->
            get_info(T,Acc);
        {initial_call, Call} ->
	    case tinfo(Pid, flags) of
		undefined ->
		    get_info(T,Acc);
		{flags,[]} ->
		    get_info(T,Acc);
		{flags,Flags} ->
		    get_info(T,[{Pid,Call,Flags}|Acc])
	    end
    end;
get_info([],Acc) -> Acc.

format_trace([]) -> [];
format_trace([Item]) -> [ts(Item)];
format_trace([Item|T]) -> [ts(Item) ," | ", format_trace(T)].

ts(send) -> "s";
ts('receive') -> "r";
ts(call) -> "c";
ts(procs) -> "p";
ts(set_on_spawn) -> "sos";
ts(set_on_first_spawn) -> "sofs";
ts(set_on_link) -> "sol";
ts(set_on_first_link) -> "sofl";
ts(Other) -> atom_to_list(Other).

%%
%% Turn (pid or) atom into a PidSpec for erlang:trace,
%% return {badpid,X} on failure 
%%

to_pidspec(X) when is_pid(X) -> 
    case erlang:is_process_alive(X) of
	true -> X;
	false -> {badpid,X}
    end;
to_pidspec(new) -> new;
to_pidspec(all) -> all;
to_pidspec(existing) -> existing;
to_pidspec(X) when is_atom(X) ->
    case whereis(X) of
	undefined -> {badpid,X};
	Pid -> Pid
    end;
to_pidspec(X) -> {badpid,X}.

%%
%% Turn (pid or) integer or tuple or list into pid
%%

to_pid(X) when is_pid(X) -> X;
to_pid(X) when is_integer(X) -> to_pid({0,X,0});
to_pid({X,Y,Z}) ->
    to_pid(lists:concat(["<",integer_to_list(X),".",
			 integer_to_list(Y),".",
			 integer_to_list(Z),">"]));
to_pid(X) when is_list(X) ->
    try list_to_pid(X) of
	Pid -> Pid
    catch
	error:badarg -> {badpid,X}
    end;
to_pid(X) -> {badpid,X}.


pinfo(P, X) when node(P) == node() -> erlang:process_info(P, X);
pinfo(P, X) -> check(rpc:call(node(P), erlang, process_info, [P, X])).

tinfo(P, X) when node(P) == node() -> erlang:trace_info(P, X);
tinfo(P, X) -> check(rpc:call(node(P), erlang, trace_info, [P, X])).

check({badrpc, _}) -> undefined;
check(X) -> X.

%% Process loop that processes a trace. Reads the trace with 
%% the reader Reader, and feeds the trace terms 
%% to handler Handler, keeping a state variable for the 
%% handler.
%%
%% Exits 'normal' at end of trace, other exits due to errors.
%%
%% Reader is a lazy list, i.e either a list or a fun/0. 
%% If it is a fun, it is evaluated for rest of the lazy list.
%% A list head is considered to be a trace term. End of list 
%% is interpreted as end of trace.

tc_loop([Term|Tail], Handler, HData0) ->
    HData = Handler(Term, HData0),
    tc_loop(Tail, Handler, HData);
tc_loop([], Handler, HData) ->
    Handler(end_of_trace, HData),
    exit(normal);
tc_loop(Reader, Handler, HData) when is_function(Reader) ->
    tc_loop(Reader(), Handler, HData);
tc_loop(Other, _Handler, _HData) ->
    io:format("~p:tc_loop ~p~n", [?MODULE, Other]),
    exit({unknown_term_from_reader, Other}).



%% Returns a reader (lazy list of trace terms) for tc_loop/2.
gen_reader(ip, {Host, Portno}) ->
    case gen_tcp:connect(Host, Portno, [{active, false}, binary]) of
        {ok, Sock} ->    
	    mk_reader(fun ip_read/2, Sock);
	Error ->
	    exit(Error)
    end;
gen_reader(file, {Filename, wrap, Tail, _, WrapCnt}) ->
    mk_reader_wrap(wrap_sort(wrap_presort(Filename, Tail), WrapCnt));
gen_reader(file, Filename) ->
    gen_reader_file(fun file_read/2, Filename);
gen_reader(follow_file, Filename) ->
    gen_reader_file(fun follow_read/2, Filename).

%% Opens a file and returns a reader (lazy list).
gen_reader_file(ReadFun, Filename) ->
    case file:open(Filename, [read, raw, binary]) of
	{ok, File} ->
	    mk_reader(ReadFun, File);
	Error ->
	    exit({client_cannot_open, Error})
    end.

%% Creates and returns a reader (lazy list).
mk_reader(ReadFun, Source) ->
    fun() ->
	    case read_term(ReadFun, Source) of
		{ok, Term} ->
		    [Term | mk_reader(ReadFun, Source)];
		eof ->
		    [] % end_of_trace
	    end
    end.

%% Creates and returns a reader (lazy list) for a wrap log.
%% The argument is a sorted list of sort converted 
%% wrap log file names, see wrap_presort/2.

mk_reader_wrap([]) ->
    [];
mk_reader_wrap([Hd | _] = WrapFiles) ->
    case file:open(wrap_name(Hd), [read, raw, binary]) of
	{ok, File} ->
	    mk_reader_wrap(WrapFiles, File);
	Error ->
	    exit({client_cannot_open, Error})
    end.

mk_reader_wrap([_Hd | Tail] = WrapFiles, File) ->
    fun() ->
	    case read_term(fun file_read/2, File) of
		{ok, Term} ->
		    [Term | mk_reader_wrap(WrapFiles, File)];
		eof ->
		    file:close(File),
		    case Tail of
			[_|_] ->
			    mk_reader_wrap(Tail);
			[] ->
			    [] % end_of_trace
		    end
	    end
    end.



%% Generic read term function. 
%% Returns {ok, Term} | 'eof'. Exits on errors.

read_term(ReadFun, Source) ->
    case ReadFun(Source, 5) of
	Bin when is_binary(Bin) ->
	    read_term(ReadFun, Source, Bin);
	List when is_list(List) ->
	    read_term(ReadFun, Source, list_to_binary(List));
	eof ->
	    eof
    end.

read_term(ReadFun, Source, <<Op, Size:32>> = Tag) ->
    case Op of
	0 ->
	    case ReadFun(Source, Size) of
		eof ->
		    exit({'trace term missing', 
			  binary_to_list(Tag)});
		Bin when is_binary(Bin) ->
		    {ok, binary_to_term(Bin)};
		List when is_list(List) ->
		    {ok, binary_to_term(list_to_binary(List))}
	    end;
	1 ->
	    {ok, {drop, Size}};
	Junk ->
	    exit({'bad trace tag', Junk})
    end.
    


%% Read functions for different source types, for read_term/2.
%%
%% Returns a binary of length N, an I/O-list of 
%% effective length N or 'eof'. Exits on errors.

file_read(File, N) ->
    case file:read(File, N) of
	{ok, Bin} when byte_size(Bin) =:= N -> 
	    Bin;
	{ok, Bin} when is_binary(Bin) ->
	    exit({'truncated file', binary_to_list(Bin)});
	eof ->
	    eof;
	{error, Reason} ->
	    exit({'file read error', Reason})
    end.

follow_read(File, N) ->
    follow_read(File, N, cur).

follow_read(File, N, Pos) ->
    case file:position(File, Pos) of
	{ok, Offset} ->
	    case file:read(File, N) of
		{ok, Bin} when byte_size(Bin) =:= N -> 
		    Bin;
		{ok, Bin} when is_binary(Bin) ->
		    follow_read(File, N, Offset);
		eof ->
		    follow_read(File, N, Offset);
		{error, Reason} ->
		    exit({'file read error', Reason})
	    end;
	{error, Reason} ->
	    exit({'file position error', Reason})
    end.

ip_read(Socket, N) ->
    case gen_tcp:recv(Socket, N) of
	{ok, Bin} when byte_size(Bin) < N ->
	    [Bin | ip_read(Socket, N-byte_size(Bin))];
	{ok, Bin} when byte_size(Bin) == N ->
	    [Bin];
	{ok, Bin} when is_binary(Bin) ->
	    exit({'socket read too much data', Bin});
	{error, closed} ->
	    eof;
	{error, _Reason} = Error ->
	    exit({'socket read error', Error})
    end.

get_tracer() ->
    req({get_tracer,node()}).
get_tracer(Node) ->
    req({get_tracer,Node}).

save_pattern([]) ->
    0;
save_pattern(P) ->
    (catch save_pattern(P, get_pattern_table())).

save_pattern(Pattern, PT) ->
    Last = last_pattern(ets:last(PT), PT),
    BPattern = term_to_binary(Pattern),
    case ets:match_object(PT, {'_', BPattern}) of
	[] ->
	    ets:insert(PT, {Last + 1, BPattern}),
	    Last + 1;
	[{N, BPattern}] ->
	    N
    end.

last_pattern('$end_of_table', _PT) ->
    0;
last_pattern(I, PT) when is_atom(I) ->
    last_pattern(ets:prev(PT, I), PT);
last_pattern(I, _PT) when is_integer(I) ->
    I;
last_pattern(_, _) ->
    throw({error, badtable}).


get_pattern_table() ->
    {ok, Ret} = req(get_table),
    Ret.

new_pattern_table() ->
    PT = ets:new(dbg_tab, [ordered_set, public]),
    ets:insert(PT, 
	       {x, 
		term_to_binary([{'_',[],[{exception_trace}]}])}),
    ets:insert(PT, 
	       {exception_trace, 
		term_to_binary(x)}),
    ets:insert(PT,
	       {c,
		term_to_binary([{'_',[],[{message,{caller}}]}])}),
    ets:insert(PT,
	       {caller_trace,
		term_to_binary(c)}),
    ets:insert(PT,
	       {cx,
		term_to_binary([{'_',[],[{exception_trace},
					 {message,{caller}}]}])}),
    ets:insert(PT,
	       {caller_exception_trace,
		term_to_binary(cx)}),
    PT.


pt_doforall(Fun, Ld) ->
    T = get_pattern_table(),
    pt_doforall(T, Fun, ets:first(T), Ld).

pt_doforall(_, _, '$end_of_table', _Ld) -> 
    ok;
pt_doforall(T, Fun, Key, Ld) ->
    [{A,B}] = ets:lookup(T,Key),
    NLd = Fun({A,binary_to_term(B)},Ld),
    pt_doforall(T,Fun,ets:next(T,Key),NLd).

lint_tp([]) ->
    {ok,[]};
lint_tp(Pattern) ->
    case erlang:match_spec_test([],Pattern,trace) of
	{ok,_Res,Warnings,_Flags} ->
	    {ok, Warnings};
	{error, Reasons} ->
	    {error, Reasons}
    end.

check_list(T) ->
    case (catch lists:foldl(
		  fun(Val,_) ->
			  {ok,_,_,_} = 
			      erlang:match_spec_test([],Val,trace),
			  ok
		  end,
		  ok, T)) of
	{'EXIT',_} ->
	    {error, bad_match_spec};
	ok ->
	    ok;
	_Else ->
	    {error, badfile}
    end.



%% Find all possible wrap log files.
%% Returns: a list of sort converted filenames.
%%
%% The sort conversion is done by extracting the wrap sequence counter
%% from the filename, and calling wrap_encode/2.
wrap_presort(Filename, Tail) ->
    Name = filename:basename(Filename),
    Dirname = filename:dirname(Filename),
    case file:list_dir(Dirname) of
	{ok, Files} ->
	    lists:zf(
	      fun(N) ->
		      case match_front(N, Name) of
			  false ->
			      false;
			  X ->
			      case match_rear(X, Tail) of
				  false ->
				      false;
				  C -> % Counter
				      case match_0_9(C) of
					  true ->
					      {true, 
					       wrap_encode(
						 filename:join(Dirname, N),
						 C)};
					  false ->
					      false
				      end
			      end
		      end
	      end,
	      Files);
	_ ->
	    []
    end.



%% Sorts a list of sort converted files
wrap_sort(Files, N) ->
    wrap_sortfix(lists:sort(Files), N).

%% Finish the sorting, since the lists:sort order is not the correct order.
%% Cut the list of files at the gap (at least one file is supposed
%% to be 'missing') and create a new list by cons'ing the two parts
%% in the right order.
wrap_sortfix([], N) when N >= 1 ->
    [];
wrap_sortfix([], _N) ->
    exit(inconsistent_wrap_file_trace_set);
%% file 0, gap 1..N
wrap_sortfix([{0, _}] = Files, N) when N >= 1 ->
    Files;
wrap_sortfix([{0, _}], _N) ->
    exit(inconsistent_wrap_file_trace_set);
%% files 0, ...
wrap_sortfix([{0, _} | _] = Files, N) when N >= 1->
    wrap_sortfix_1(Files, N, [], Files);
%% gap 0, files 1, ...
wrap_sortfix([{1, _} | _] = Files, N) when N >= 1 ->
    wrap_sortfix_2(Files, N, [], Files);
wrap_sortfix([{_C, _} | _], _N) ->
    exit(inconsistent_wrap_file_trace_set).

%% files 0..C, gap C+1..N
wrap_sortfix_1([{C, _}], N, _R, Files) 
  when C < N ->
    Files;
%% files 0..C1, C1+1==C2, ...
wrap_sortfix_1([{C1, _} = F1 | [{C2, _} | _] = Tail], N, R, Files) 
  when C1+1 == C2, C2 < N ->
    wrap_sortfix_1(Tail, N, [F1 | R], Files);
%% files 0..C1, gap C1+1, files C1+2==C2, ...
wrap_sortfix_1([{C1, _} = F1 | [{C2, _} | _] = Tail], N, R, _Files) 
  when C1+2 == C2, C2 =< N ->
    wrap_sortfix_2(Tail, N, lists:reverse([F1 | R]), Tail);
wrap_sortfix_1([_F1 | [_F2 | _]], _N, _R, _Files) ->
    exit(inconsistent_wrap_file_trace_set).

%% M == length(R); files 0..M-1, gap M, files M+1..N
wrap_sortfix_2([{N, _}], N, R, Files) ->
    Files ++ R;
wrap_sortfix_2([{_C, _}], _N, _R, _Files) ->
    exit(inconsistent_wrap_file_trace_set);
%% M == length(R); files 0..M-1, gap M, files M+1..C1, C1+1==C2, ...
wrap_sortfix_2([{C1, _} | [{C2, _} | _] = Tail], N, R, Files)
  when C1+1 == C2, C2 =< N ->
    wrap_sortfix_2(Tail, N, R, Files);
wrap_sortfix_2([{_C1, _} | [{_C2, _} | _]], _N, _R, _Files) ->
    exit(inconsistent_wrap_file_trace_set).



%% Extract the filenames from a list of sort converted ones.
wrap_postsort(Files) ->    
    lists:map(fun wrap_name/1, Files).

wrap_encode(N, C) ->
    {list_to_integer(C), N}.

wrap_name({_C, N}) ->
    N.

%% Returns what is left of ListA when removing all matching
%% elements from ListB, or false if some element did not match,
%% or if ListA runs out of elements before ListB.
match_front(ListA, []) when is_list(ListA) ->
    ListA;
match_front([], ListB) when is_list(ListB) ->
    false;
match_front([Hd|TlA], [Hd|TlB]) ->
    match_front(TlA,TlB);
match_front([_HdA|_], [_HdB|_]) ->
    false.

%% Reversed version of match_front/2
match_rear(ListA, ListB) when is_list(ListA), is_list(ListB) ->
    case match_front(lists:reverse(ListA), lists:reverse(ListB)) of
	false ->
	    false;
	List ->
	    lists:reverse(List)
    end.

%% Returns true if the non-empty list arguments contains all
%% characters $0 .. $9.
match_0_9([]) ->
    false;
match_0_9([H]) when is_integer(H), $0 =< H, H =< $9 ->
    true;
match_0_9([H|T]) when is_integer(H), $0 =< H, H =< $9 ->
    match_0_9(T);
match_0_9(L) when is_list(L) ->
    false.

%%%%%%%%%%%%%%%%%%
%% Help...
%%%%%%%%%%%%%%%%%%

help_display([]) ->
    io:format("~n",[]),
    ok;
help_display([H|T]) ->
    io:format("~s~n",[H]),
    help_display(T).

h() ->
    help_display(
      [
       "The following help items are available:",
       "   p, c",
       "       - Set trace flags for processes",
       "   tp, tpl, ctp, ctpl, ctpg, ltp, dtp, wtp, rtp",
       "       - Manipulate trace patterns for functions",
       "   n, cn, ln",
       "       - Add/remove traced nodes.",
       "   tracer, trace_port, trace_client, get_tracer, stop, stop_clear", 
       "       - Manipulate tracer process/port",
       "   i",
       "       - Info", 
       "",
       "call dbg:h(Item) for brief help a brief description",
       "of one of the items above."]).
h(p) ->
    help_display(["p(Item) -> {ok, MatchDesc} | {error, term()}",
		  " - Traces messages to and from Item.",
		  "p(Item, Flags) -> {ok, MatchDesc} | {error, term()}",
		  " - Traces Item according to Flags.",
		  "   Flags can be one of s,r,m,c,p,sos,sol,sofs,",
		  "   sofl,all,clear or any flag accepted by erlang:trace/3"]);
h(c) ->
    help_display(["c(Mod, Fun, Args)",
		  " - Evaluates apply(M,F,Args) with all trace flags set.",
		  "c(Mod, Fun, Args, Flags)",
		  " - Evaluates apply(M,F,Args) with Flags trace flags set."]);
h(i) ->
    help_display(["i() -> ok",
		  " - Displays information about all traced processes."]);
h(tp) ->
    help_display(
      ["tp(Module,MatchSpec)",
       " - Same as tp({Module, '_', '_'}, MatchSpec)",
       "tp(Module,Function,MatchSpec)",
       " - Same as tp({Module, Function, '_'}, MatchSpec)",
       "tp(Module, Function, Arity, MatchSpec)",
       " - Same as tp({Module, Function, Arity}, MatchSpec)",
       "tp({Module, Function, Arity}, MatchSpec) -> {ok, MatchDesc} "
       "| {error, term()}",
       " - Set pattern for traced global function calls."]);
h(tpl) ->
    help_display(
      ["tpl(Module,MatchSpec)",
       " - Same as tpl({Module, '_', '_'}, MatchSpec)",
       "tpl(Module,Function,MatchSpec)",
       " - Same as tpl({Module, Function, '_'}, MatchSpec)",
       "tpl(Module, Function, Arity, MatchSpec)",
       " - Same as tpl({Module, Function, Arity}, MatchSpec)",
       "tpl({Module, Function, Arity}, MatchSpec) -> {ok, MatchDesc} "
       "| {error, term()}",
       " - Set pattern for traced local (as well as global) function calls."]);
h(ctp) ->
    help_display(
      ["ctp()",
       " - Same as ctp({'_', '_', '_'})",
       "ctp(Module)",
       " - Same as ctp({Module, '_', '_'})",
       "ctp(Module, Function)",
       " - Same as ctp({Module, Function, '_'})",
       "ctp(Module, Function, Arity)",
       " - Same as ctp({Module, Function, Arity})",
       "ctp({Module, Function, Arity}) -> {ok, MatchDesc} | {error, term()}",
       " - Clear call trace pattern for the specified functions"]);
h(ctpl) ->
    help_display(
      ["ctpl()",
       " - Same as ctpl({'_', '_', '_'})",
       "ctpl(Module)",
       " - Same as ctpl({Module, '_', '_'})",
       "ctpl(Module, Function)",
       " - Same as ctpl({Module, Function, '_'})",
       "ctpl(Module, Function, Arity)",
       " - Same as ctpl({Module, Function, Arity})",
       "ctpl({Module, Function, Arity}) -> {ok, MatchDesc} | {error, term()}",
       " - Clear local call trace pattern for the specified functions"]);
h(ctpg) ->
    help_display(
      ["ctpg()",
       " - Same as ctpg({'_', '_', '_'})",
       "ctpg(Module)",
       " - Same as ctpg({Module, '_', '_'})",
       "ctpg(Module, Function)",
       " - Same as ctpg({Module, Function, '_'})",
       "ctpg(Module, Function, Arity)",
       " - Same as ctpg({Module, Function, Arity})",
       "ctpg({Module, Function, Arity}) -> {ok, MatchDesc} | {error, term()}",
       " - Clear global call trace pattern for the specified functions"]);
h(ltp) ->
    help_display(["ltp() -> ok",
		  " - Lists saved and built-in match_spec's on the console."]);
h(dtp) ->
    help_display(["dtp() -> ok",
		  " - Deletes all saved match_spec's.",
		  "dtp(N) -> ok",
		  " - Deletes a specific saved match_spec."]);
h(wtp) ->
    help_display(["wtp(Name) -> ok | {error, IOError}",
		  " - Writes all saved match_spec's to a file"]);
h(rtp) ->
    help_display(["rtp(Name) -> ok | {error, Error}",
		  " - Read saved match specifications from file."]);
h(n) ->
    help_display(
      ["n(Nodename) -> {ok, Nodename} | {error, Reason}",
       " - Starts a tracer server on the given node.",
       "n(Nodename,Type,Data) -> {ok, Nodename} | {error, Reason}",
       " - Starts a tracer server with additional args on the given node."]);
h(cn) ->
    help_display(["cn(Nodename) -> ok",
		  " - Clears a node from the list of traced nodes."]);
h(ln) ->
    help_display(["ln() -> ok",
		  " - Shows the list of traced nodes on the console."]);
h(tracer) ->
    help_display(["tracer() -> {ok, pid()} | {error, already_started}",
		  " - Starts a tracer server that handles trace messages.",
		  "tracer(Type, Data) -> {ok, pid()} | {error, Error}",
		  " - Starts a tracer server with additional parameters"]);
h(trace_port) ->
    help_display(["trace_port(Type, Parameters) -> fun()",
		  " - Creates and returns a trace port generating fun"]);
h(trace_client) ->
    help_display(["trace_client(Type, Parameters) -> pid()",
		  " - Starts a trace client that reads messages created by "
		  "a trace port driver",
		  "trace_client(Type, Parameters, HandlerSpec) -> pid()",
		  " - Starts a trace client that reads messages created by a",
		  "   trace port driver, with a user defined handler"]);
h(get_tracer) ->
    help_display(
      ["get_tracer() -> {ok, Tracer}",
       " - Returns the process or port to which all trace messages are sent.",
      "get_tracer(Node) -> {ok, Tracer}",
       " - Returns the process or port to which all trace messages are sent."]);
h(stop) ->
    help_display(
      ["stop() -> stopped",
       " - Stops the dbg server and the tracing of all processes.",
       "   Does not clear any trace patterns."]);
h(stop_clear) ->
    help_display(
      ["stop_clear() -> stopped",
       " - Stops the dbg server and the tracing of all processes,",
       "   and clears all trace patterns."]).