summaryrefslogtreecommitdiffstats
path: root/win/tclWinConsole.c
blob: 1648ad7e39a8b2e5950de8e0da6ba311e3d534cd (plain)
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
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
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
/* 
 * tclWinConsole.c --
 *
 *	This file implements the Windows-specific console functions,
 *	and the "console" channel driver.
 *
 * Copyright (c) 1999 by Scriptics Corp.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclWinConsole.c,v 1.13 2005/01/27 00:23:33 andreas_kupries Exp $
 */

#include "tclWinInt.h"

#include <fcntl.h>
#include <io.h>
#include <sys/stat.h>

/*
 * The following variable is used to tell whether this module has been
 * initialized.
 */

static int initialized = 0;

/*
 * The consoleMutex locks around access to the initialized variable, and it is
 * used to protect background threads from being terminated while they are
 * using APIs that hold locks.
 */

TCL_DECLARE_MUTEX(consoleMutex)

/*
 * Bit masks used in the flags field of the ConsoleInfo structure below.
 */

#define CONSOLE_PENDING	(1<<0)	/* Message is pending in the queue. */
#define CONSOLE_ASYNC	(1<<1)	/* Channel is non-blocking. */

/*
 * Bit masks used in the sharedFlags field of the ConsoleInfo structure below.
 */

#define CONSOLE_EOF	  (1<<2)  /* Console has reached EOF. */
#define CONSOLE_BUFFERED  (1<<3)  /* data was read into a buffer by the reader
				     thread */

#define CONSOLE_BUFFER_SIZE (8*1024)
/*
 * This structure describes per-instance data for a console based channel.
 */

typedef struct ConsoleInfo {
    HANDLE handle;
    int type;
    struct ConsoleInfo *nextPtr;/* Pointer to next registered console. */
    Tcl_Channel channel;	/* Pointer to channel structure. */
    int validMask;		/* OR'ed combination of TCL_READABLE,
				 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
				 * which operations are valid on the file. */
    int watchMask;		/* OR'ed combination of TCL_READABLE,
				 * TCL_WRITABLE, or TCL_EXCEPTION: indicates
				 * which events should be reported. */
    int flags;			/* State flags, see above for a list. */
    Tcl_ThreadId threadId;	/* Thread to which events should be reported.
				 * This value is used by the reader/writer
				 * threads. */
    HANDLE writeThread;		/* Handle to writer thread. */
    HANDLE readThread;		/* Handle to reader thread. */
    HANDLE writable;		/* Manual-reset event to signal when the
				 * writer thread has finished waiting for
				 * the current buffer to be written. */
    HANDLE readable;		/* Manual-reset event to signal when the
				 * reader thread has finished waiting for
				 * input. */
    HANDLE startWriter;		/* Auto-reset event used by the main thread to
				 * signal when the writer thread should attempt
				 * to write to the console. */
    HANDLE stopWriter;		/* Auto-reset event used by the main thread to
				 * signal when the writer thread should exit.
				 */
    HANDLE startReader;		/* Auto-reset event used by the main thread to
				 * signal when the reader thread should attempt
				 * to read from the console. */
    HANDLE stopReader;		/* Auto-reset event used by the main thread to
				 * signal when the reader thread should exit.
				 */
    DWORD writeError;		/* An error caused by the last background
				 * write.  Set to 0 if no error has been
				 * detected.  This word is shared with the
				 * writer thread so access must be
				 * synchronized with the writable object.
				 */
    char *writeBuf;		/* Current background output buffer.
				 * Access is synchronized with the writable
				 * object. */
    int writeBufLen;		/* Size of write buffer.  Access is
				 * synchronized with the writable
				 * object. */
    int toWrite;		/* Current amount to be written.  Access is
				 * synchronized with the writable object. */
    int readFlags;		/* Flags that are shared with the reader
				 * thread.  Access is synchronized with the
				 * readable object.  */
    int bytesRead;              /* number of bytes in the buffer */
    int offset;                 /* number of bytes read out of the buffer */
    char buffer[CONSOLE_BUFFER_SIZE];
                                /* Data consumed by reader thread. */
} ConsoleInfo;

typedef struct ThreadSpecificData {
    /*
     * The following pointer refers to the head of the list of consoles
     * that are being watched for file events.
     */
    
    ConsoleInfo *firstConsolePtr;
} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;

/*
 * The following structure is what is added to the Tcl event queue when
 * console events are generated.
 */

typedef struct ConsoleEvent {
    Tcl_Event header;		/* Information that is standard for
				 * all events. */
    ConsoleInfo *infoPtr;	/* Pointer to console info structure.  Note
				 * that we still have to verify that the
				 * console exists before dereferencing this
				 * pointer. */
} ConsoleEvent;

/*
 * Declarations for functions used only in this file.
 */

static int		ConsoleBlockModeProc(ClientData instanceData, int mode);
static void		ConsoleCheckProc(ClientData clientData, int flags);
static int		ConsoleCloseProc(ClientData instanceData,
			    Tcl_Interp *interp);
static int		ConsoleEventProc(Tcl_Event *evPtr, int flags);
static void		ConsoleExitHandler(ClientData clientData);
static int		ConsoleGetHandleProc(ClientData instanceData,
			    int direction, ClientData *handlePtr);
static void             ConsoleInit(void);
static int		ConsoleInputProc(ClientData instanceData, char *buf,
			    int toRead, int *errorCode);
static int		ConsoleOutputProc(ClientData instanceData,
			    CONST char *buf, int toWrite, int *errorCode);
static DWORD WINAPI	ConsoleReaderThread(LPVOID arg);
static void		ConsoleSetupProc(ClientData clientData, int flags);
static void		ConsoleWatchProc(ClientData instanceData, int mask);
static DWORD WINAPI	ConsoleWriterThread(LPVOID arg);
static void		ProcExitHandler(ClientData clientData);
static int		WaitForRead(ConsoleInfo *infoPtr, int blocking);

static void             ConsoleThreadActionProc _ANSI_ARGS_ ((
			   ClientData instanceData, int action));

/*
 * This structure describes the channel type structure for command console
 * based IO.
 */

static Tcl_ChannelType consoleChannelType = {
    "console",			/* Type name. */
    TCL_CHANNEL_VERSION_4,	/* v4 channel */
    ConsoleCloseProc,		/* Close proc. */
    ConsoleInputProc,		/* Input proc. */
    ConsoleOutputProc,		/* Output proc. */
    NULL,			/* Seek proc. */
    NULL,			/* Set option proc. */
    NULL,			/* Get option proc. */
    ConsoleWatchProc,		/* Set up notifier to watch the channel. */
    ConsoleGetHandleProc,	/* Get an OS handle from channel. */
    NULL,			/* close2proc. */
    ConsoleBlockModeProc,	/* Set blocking or non-blocking mode.*/
    NULL,			/* flush proc. */
    NULL,			/* handler proc. */
    NULL,                       /* wide seek proc */
    ConsoleThreadActionProc,    /* thread action proc */
};

/*
 *----------------------------------------------------------------------
 *
 * ConsoleInit --
 *
 *	This function initializes the static variables for this file.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Creates a new event source.
 *
 *----------------------------------------------------------------------
 */

static void
ConsoleInit()
{
    ThreadSpecificData *tsdPtr;

    /*
     * Check the initialized flag first, then check again in the mutex.
     * This is a speed enhancement.
     */

    if (!initialized) {
	Tcl_MutexLock(&consoleMutex);
	if (!initialized) {
	    initialized = 1;
	    Tcl_CreateExitHandler(ProcExitHandler, NULL);
	}
	Tcl_MutexUnlock(&consoleMutex);
    }

    tsdPtr = (ThreadSpecificData *)TclThreadDataKeyGet(&dataKey);
    if (tsdPtr == NULL) {
	tsdPtr = TCL_TSD_INIT(&dataKey);
	tsdPtr->firstConsolePtr = NULL;
	Tcl_CreateEventSource(ConsoleSetupProc, ConsoleCheckProc, NULL);
	Tcl_CreateThreadExitHandler(ConsoleExitHandler, NULL);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleExitHandler --
 *
 *	This function is called to cleanup the console module before
 *	Tcl is unloaded.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Removes the console event source.
 *
 *----------------------------------------------------------------------
 */

static void
ConsoleExitHandler(
    ClientData clientData)	/* Old window proc */
{
    Tcl_DeleteEventSource(ConsoleSetupProc, ConsoleCheckProc, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * ProcExitHandler --
 *
 *	This function is called to cleanup the process list before
 *	Tcl is unloaded.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Resets the process list.
 *
 *----------------------------------------------------------------------
 */

static void
ProcExitHandler(
    ClientData clientData)	/* Old window proc */
{
    Tcl_MutexLock(&consoleMutex);
    initialized = 0;
    Tcl_MutexUnlock(&consoleMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleSetupProc --
 *
 *	This procedure is invoked before Tcl_DoOneEvent blocks waiting
 *	for an event.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Adjusts the block time if needed.
 *
 *----------------------------------------------------------------------
 */

void
ConsoleSetupProc(
    ClientData data,		/* Not used. */
    int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
{
    ConsoleInfo *infoPtr;
    Tcl_Time blockTime = { 0, 0 };
    int block = 1;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
	return;
    }
    
    /*
     * Look to see if any events are already pending.  If they are, poll.
     */

    for (infoPtr = tsdPtr->firstConsolePtr; infoPtr != NULL; 
	    infoPtr = infoPtr->nextPtr) {
	if (infoPtr->watchMask & TCL_WRITABLE) {
	    if (WaitForSingleObject(infoPtr->writable, 0) != WAIT_TIMEOUT) {
		block = 0;
	    }
	}
	if (infoPtr->watchMask & TCL_READABLE) {
	    if (WaitForRead(infoPtr, 0) >= 0) {
		block = 0;
	    }
	}
    }
    if (!block) {
	Tcl_SetMaxBlockTime(&blockTime);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleCheckProc --
 *
 *	This procedure is called by Tcl_DoOneEvent to check the console
 *	event source for events. 
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May queue an event.
 *
 *----------------------------------------------------------------------
 */

static void
ConsoleCheckProc(
    ClientData data,		/* Not used. */
    int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
{
    ConsoleInfo *infoPtr;
    ConsoleEvent *evPtr;
    int needEvent;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
	return;
    }
    
    /*
     * Queue events for any ready consoles that don't already have events
     * queued.
     */

    for (infoPtr = tsdPtr->firstConsolePtr; infoPtr != NULL; 
	    infoPtr = infoPtr->nextPtr) {
	if (infoPtr->flags & CONSOLE_PENDING) {
	    continue;
	}
	
	/*
	 * Queue an event if the console is signaled for reading or writing.
	 */

	needEvent = 0;
	if (infoPtr->watchMask & TCL_WRITABLE) {
	    if (WaitForSingleObject(infoPtr->writable, 0) != WAIT_TIMEOUT) {
		needEvent = 1;
	    }
	}
	
	if (infoPtr->watchMask & TCL_READABLE) {
	    if (WaitForRead(infoPtr, 0) >= 0) {
		needEvent = 1;
	    }
	}

	if (needEvent) {
	    infoPtr->flags |= CONSOLE_PENDING;
	    evPtr = (ConsoleEvent *) ckalloc(sizeof(ConsoleEvent));
	    evPtr->header.proc = ConsoleEventProc;
	    evPtr->infoPtr = infoPtr;
	    Tcl_QueueEvent((Tcl_Event *) evPtr, TCL_QUEUE_TAIL);
	}
    }
}


/*
 *----------------------------------------------------------------------
 *
 * ConsoleBlockModeProc --
 *
 *	Set blocking or non-blocking mode on channel.
 *
 * Results:
 *	0 if successful, errno when failed.
 *
 * Side effects:
 *	Sets the device into blocking or non-blocking mode.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleBlockModeProc(
    ClientData instanceData,	/* Instance data for channel. */
    int mode)			/* TCL_MODE_BLOCKING or
                                 * TCL_MODE_NONBLOCKING. */
{
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;
    
    /*
     * Consoles on Windows can not be switched between blocking and nonblocking,
     * hence we have to emulate the behavior. This is done in the input
     * function by checking against a bit in the state. We set or unset the
     * bit here to cause the input function to emulate the correct behavior.
     */

    if (mode == TCL_MODE_NONBLOCKING) {
	infoPtr->flags |= CONSOLE_ASYNC;
    } else {
	infoPtr->flags &= ~(CONSOLE_ASYNC);
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleCloseProc --
 *
 *	Closes a console based IO channel.
 *
 * Results:
 *	0 on success, errno otherwise.
 *
 * Side effects:
 *	Closes the physical channel.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleCloseProc(
    ClientData instanceData,	/* Pointer to ConsoleInfo structure. */
    Tcl_Interp *interp)		/* For error reporting. */
{
    ConsoleInfo *consolePtr = (ConsoleInfo *) instanceData;
    int errorCode;
    ConsoleInfo *infoPtr, **nextPtrPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    DWORD exitCode;

    errorCode = 0;
    
    /*
     * Clean up the background thread if necessary.  Note that this
     * must be done before we can close the file, since the 
     * thread may be blocking trying to read from the console.
     */
    
    if (consolePtr->readThread) {

	/*
	 * The thread may already have closed on it's own.  Check it's
	 * exit code.
	 */

	GetExitCodeThread(consolePtr->readThread, &exitCode);

	if (exitCode == STILL_ACTIVE) {

	    /*
	     * Set the stop event so that if the reader thread is blocked
	     * in ConsoleReaderThread on WaitForMultipleEvents, it will exit
	     * cleanly.
	     */

	    SetEvent(consolePtr->stopReader);

	    /*
	     * Wait at most 20 milliseconds for the reader thread to close.
	     */

	    if (WaitForSingleObject(consolePtr->readThread, 20)
		    == WAIT_TIMEOUT) {
		/*
		 * Forcibly terminate the background thread as a last
		 * resort.  Note that we need to guard against
		 * terminating the thread while it is in the middle of
		 * Tcl_ThreadAlert because it won't be able to release
		 * the notifier lock.
		 */

		Tcl_MutexLock(&consoleMutex);

		/* BUG: this leaks memory. */
		TerminateThread(consolePtr->readThread, 0);
		Tcl_MutexUnlock(&consoleMutex);
	    }
	}

	CloseHandle(consolePtr->readThread);
	CloseHandle(consolePtr->readable);
	CloseHandle(consolePtr->startReader);
	CloseHandle(consolePtr->stopReader);
	consolePtr->readThread = NULL;
    }
    consolePtr->validMask &= ~TCL_READABLE;

    /*
     * Wait for the writer thread to finish the current buffer, then
     * terminate the thread and close the handles.  If the channel is
     * nonblocking, there should be no pending write operations.
     */
    
    if (consolePtr->writeThread) {
	if (consolePtr->toWrite) {
	    /*
	     * We only need to wait if there is something to write.
	     * This may prevent infinite wait on exit. [python bug 216289]
	     */
	    WaitForSingleObject(consolePtr->writable, INFINITE);
	}

	/*
	 * The thread may already have closed on it's own.  Check it's
	 * exit code.
	 */

	GetExitCodeThread(consolePtr->writeThread, &exitCode);

	if (exitCode == STILL_ACTIVE) {
	    /*
	     * Set the stop event so that if the reader thread is blocked
	     * in ConsoleWriterThread on WaitForMultipleEvents, it will
	     * exit cleanly.
	     */

	    SetEvent(consolePtr->stopWriter);

	    /*
	     * Wait at most 20 milliseconds for the writer thread to close.
	     */

	    if (WaitForSingleObject(consolePtr->writeThread, 20)
		    == WAIT_TIMEOUT) {
		/*
		 * Forcibly terminate the background thread as a last
		 * resort.  Note that we need to guard against
		 * terminating the thread while it is in the middle of
		 * Tcl_ThreadAlert because it won't be able to release
		 * the notifier lock.
		 */

		Tcl_MutexLock(&consoleMutex);

		/* BUG: this leaks memory. */
		TerminateThread(consolePtr->writeThread, 0);
		Tcl_MutexUnlock(&consoleMutex);
	    }
	}

	CloseHandle(consolePtr->writeThread);
	CloseHandle(consolePtr->writable);
	CloseHandle(consolePtr->startWriter);
	CloseHandle(consolePtr->stopWriter);
	consolePtr->writeThread = NULL;
    }
    consolePtr->validMask &= ~TCL_WRITABLE;


    /*
     * Don't close the Win32 handle if the handle is a standard channel
     * during the thread exit process.  Otherwise, one thread may kill
     * the stdio of another.
     */

    if (!TclInThreadExit() 
	    || ((GetStdHandle(STD_INPUT_HANDLE) != consolePtr->handle)
		&& (GetStdHandle(STD_OUTPUT_HANDLE) != consolePtr->handle)
		&& (GetStdHandle(STD_ERROR_HANDLE) != consolePtr->handle))) {
	if (CloseHandle(consolePtr->handle) == FALSE) {
	    TclWinConvertError(GetLastError());
	    errorCode = errno;
	}
    }
    
    consolePtr->watchMask &= consolePtr->validMask;

    /*
     * Remove the file from the list of watched files.
     */

    for (nextPtrPtr = &(tsdPtr->firstConsolePtr), infoPtr = *nextPtrPtr;
	    infoPtr != NULL;
	    nextPtrPtr = &infoPtr->nextPtr, infoPtr = *nextPtrPtr) {
	if (infoPtr == (ConsoleInfo *)consolePtr) {
	    *nextPtrPtr = infoPtr->nextPtr;
	    break;
	}
    }
    if (consolePtr->writeBuf != NULL) {
	ckfree(consolePtr->writeBuf);
	consolePtr->writeBuf = 0;
    }
    ckfree((char*) consolePtr);

    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleInputProc --
 *
 *	Reads input from the IO channel into the buffer given. Returns
 *	count of how many bytes were actually read, and an error indication.
 *
 * Results:
 *	A count of how many bytes were read is returned and an error
 *	indication is returned in an output argument.
 *
 * Side effects:
 *	Reads input from the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleInputProc(
    ClientData instanceData,		/* Console state. */
    char *buf,				/* Where to store data read. */
    int bufSize,			/* How much space is available
                                         * in the buffer? */
    int *errorCode)			/* Where to store error code. */
{
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;
    DWORD count, bytesRead = 0;
    int result;

    *errorCode = 0;

    /*
     * Synchronize with the reader thread.
     */
    
    result = WaitForRead(infoPtr, (infoPtr->flags & CONSOLE_ASYNC) ? 0 : 1);
    
    /*
     * If an error occurred, return immediately.
     */
    
    if (result == -1) {
	*errorCode = errno;
	return -1;
    }

    if (infoPtr->readFlags & CONSOLE_BUFFERED) {
	/*
	 * Data is stored in the buffer.
	 */

	if (bufSize < (infoPtr->bytesRead - infoPtr->offset)) {
	    memcpy(buf, &infoPtr->buffer[infoPtr->offset], (size_t) bufSize);
	    bytesRead = bufSize;
	    infoPtr->offset += bufSize;
	} else {
	    memcpy(buf, &infoPtr->buffer[infoPtr->offset], (size_t) bufSize);
	    bytesRead = infoPtr->bytesRead - infoPtr->offset;

	    /*
	     * Reset the buffer
	     */
	    
	    infoPtr->readFlags &= ~CONSOLE_BUFFERED;
	    infoPtr->offset = 0;
	}

	return bytesRead;
    }
    
    /*
     * Attempt to read bufSize bytes.  The read will return immediately
     * if there is any data available.  Otherwise it will block until
     * at least one byte is available or an EOF occurs.
     */

    if (ReadConsole(infoPtr->handle, (LPVOID) buf, (DWORD) bufSize, &count,
		    (LPOVERLAPPED) NULL) == TRUE) {
	buf[count] = '\0';
	return count;
    }

    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleOutputProc --
 *
 *	Writes the given output on the IO channel. Returns count of how
 *	many characters were actually written, and an error indication.
 *
 * Results:
 *	A count of how many characters were written is returned and an
 *	error indication is returned in an output argument.
 *
 * Side effects:
 *	Writes output on the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleOutputProc(
    ClientData instanceData,		/* Console state. */
    CONST char *buf,			/* The data buffer. */
    int toWrite,			/* How many bytes to write? */
    int *errorCode)			/* Where to store error code. */
{
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;
    DWORD bytesWritten, timeout;

    *errorCode = 0;
    timeout = (infoPtr->flags & CONSOLE_ASYNC) ? 0 : INFINITE;
    if (WaitForSingleObject(infoPtr->writable, timeout) == WAIT_TIMEOUT) {
	/*
	 * The writer thread is blocked waiting for a write to complete
	 * and the channel is in non-blocking mode.
	 */

	errno = EAGAIN;
	goto error;
    }

    /*
     * Check for a background error on the last write.
     */

    if (infoPtr->writeError) {
	TclWinConvertError(infoPtr->writeError);
	infoPtr->writeError = 0;
	goto error;
    }

    if (infoPtr->flags & CONSOLE_ASYNC) {
	/*
	 * The console is non-blocking, so copy the data into the output
	 * buffer and restart the writer thread.
	 */

	if (toWrite > infoPtr->writeBufLen) {
	    /*
	     * Reallocate the buffer to be large enough to hold the data.
	     */

	    if (infoPtr->writeBuf) {
		ckfree(infoPtr->writeBuf);
	    }
	    infoPtr->writeBufLen = toWrite;
	    infoPtr->writeBuf = ckalloc(toWrite);
	}
	memcpy(infoPtr->writeBuf, buf, toWrite);
	infoPtr->toWrite = toWrite;
	ResetEvent(infoPtr->writable);
	SetEvent(infoPtr->startWriter);
	bytesWritten = toWrite;
    } else {
	/*
	 * In the blocking case, just try to write the buffer directly.
	 * This avoids an unnecessary copy.
	 */

	if (WriteConsole(infoPtr->handle, buf, toWrite, &bytesWritten,
		NULL) == FALSE) {
	    TclWinConvertError(GetLastError());
	    goto error;
	}
    }
    return bytesWritten;

error:
    *errorCode = errno;
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleEventProc --
 *
 *	This function is invoked by Tcl_ServiceEvent when a file event
 *	reaches the front of the event queue.  This procedure invokes
 *	Tcl_NotifyChannel on the console.
 *
 * Results:
 *	Returns 1 if the event was handled, meaning it should be removed
 *	from the queue.  Returns 0 if the event was not handled, meaning
 *	it should stay on the queue.  The only time the event isn't
 *	handled is if the TCL_FILE_EVENTS flag bit isn't set.
 *
 * Side effects:
 *	Whatever the notifier callback does.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleEventProc(
    Tcl_Event *evPtr,		/* Event to service. */
    int flags)			/* Flags that indicate what events to
				 * handle, such as TCL_FILE_EVENTS. */
{
    ConsoleEvent *consoleEvPtr = (ConsoleEvent *)evPtr;
    ConsoleInfo *infoPtr;
    int mask;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
	return 0;
    }

    /*
     * Search through the list of watched consoles for the one whose handle
     * matches the event.  We do this rather than simply dereferencing
     * the handle in the event so that consoles can be deleted while the
     * event is in the queue.
     */

    for (infoPtr = tsdPtr->firstConsolePtr; infoPtr != NULL;
	    infoPtr = infoPtr->nextPtr) {
	if (consoleEvPtr->infoPtr == infoPtr) {
	    infoPtr->flags &= ~(CONSOLE_PENDING);
	    break;
	}
    }

    /*
     * Remove stale events.
     */

    if (!infoPtr) {
	return 1;
    }

    /*
     * Check to see if the console is readable.  Note
     * that we can't tell if a console is writable, so we always report it
     * as being writable unless we have detected EOF.
     */

    mask = 0;
    if (infoPtr->watchMask & TCL_WRITABLE) {
	if (WaitForSingleObject(infoPtr->writable, 0) != WAIT_TIMEOUT) {
	    mask = TCL_WRITABLE;
	}
    }

    if (infoPtr->watchMask & TCL_READABLE) {
	if (WaitForRead(infoPtr, 0) >= 0) {
	    if (infoPtr->readFlags & CONSOLE_EOF) {
		mask = TCL_READABLE;
	    } else {
		mask |= TCL_READABLE;
	    }
	} 
    }

    /*
     * Inform the channel of the events.
     */

    Tcl_NotifyChannel(infoPtr->channel, infoPtr->watchMask & mask);
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleWatchProc --
 *
 *	Called by the notifier to set up to watch for events on this
 *	channel.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static void
ConsoleWatchProc(
    ClientData instanceData,		/* Console state. */
    int mask)				/* What events to watch for, OR-ed
                                         * combination of TCL_READABLE,
                                         * TCL_WRITABLE and TCL_EXCEPTION. */
{
    ConsoleInfo **nextPtrPtr, *ptr;
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;
    int oldMask = infoPtr->watchMask;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    /*
     * Since most of the work is handled by the background threads,
     * we just need to update the watchMask and then force the notifier
     * to poll once. 
     */

    infoPtr->watchMask = mask & infoPtr->validMask;
    if (infoPtr->watchMask) {
	Tcl_Time blockTime = { 0, 0 };
	if (!oldMask) {
	    infoPtr->nextPtr = tsdPtr->firstConsolePtr;
	    tsdPtr->firstConsolePtr = infoPtr;
	}
	Tcl_SetMaxBlockTime(&blockTime);
    } else {
	if (oldMask) {
	    /*
	     * Remove the console from the list of watched consoles.
	     */

	    for (nextPtrPtr = &(tsdPtr->firstConsolePtr), ptr = *nextPtrPtr;
		 ptr != NULL;
		 nextPtrPtr = &ptr->nextPtr, ptr = *nextPtrPtr) {
		if (infoPtr == ptr) {
		    *nextPtrPtr = ptr->nextPtr;
		    break;
		}
	    }
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleGetHandleProc --
 *
 *	Called from Tcl_GetChannelHandle to retrieve OS handles from
 *	inside a command consoleline based channel.
 *
 * Results:
 *	Returns TCL_OK with the fd in handlePtr, or TCL_ERROR if
 *	there is no handle for the specified direction. 
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
ConsoleGetHandleProc(
    ClientData instanceData,	/* The console state. */
    int direction,		/* TCL_READABLE or TCL_WRITABLE */
    ClientData *handlePtr)	/* Where to store the handle.  */
{
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;

    *handlePtr = (ClientData) infoPtr->handle;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * WaitForRead --
 *
 *	Wait until some data is available, the console is at
 *	EOF or the reader thread is blocked waiting for data (if the
 *	channel is in non-blocking mode).
 *
 * Results:
 *	Returns 1 if console is readable.  Returns 0 if there is no data
 *	on the console, but there is buffered data.  Returns -1 if an
 *	error occurred.  If an error occurred, the threads may not
 *	be synchronized.
 *
 * Side effects:
 *	Updates the shared state flags.  If no error occurred,
 *      the reader thread is blocked waiting for a signal from the 
 *      main thread.
 *
 *----------------------------------------------------------------------
 */

static int
WaitForRead(
    ConsoleInfo *infoPtr,		/* Console state. */
    int blocking)		/* Indicates whether call should be
				 * blocking or not. */
{
    DWORD timeout, count;
    HANDLE *handle = infoPtr->handle;
    INPUT_RECORD input;
    
    while (1) {
	/*
	 * Synchronize with the reader thread.
	 */
       
	timeout = blocking ? INFINITE : 0;
	if (WaitForSingleObject(infoPtr->readable, timeout) == WAIT_TIMEOUT) {
	    /*
	     * The reader thread is blocked waiting for data and the channel
	     * is in non-blocking mode.
	     */
	    errno = EAGAIN;
	    return -1;
	}
	
	/*
	 * At this point, the two threads are synchronized, so it is safe
	 * to access shared state.
	 */
	
	/*
	 * If the console has hit EOF, it is always readable.
	 */
	
	if (infoPtr->readFlags & CONSOLE_EOF) {
	    return 1;
	}
	
	if (PeekConsoleInput(handle, &input, 1, &count) == FALSE) {
            /*
	     * Check to see if the peek failed because of EOF.
	     */
	    
	    TclWinConvertError(GetLastError());
	    
	    if (errno == EOF) {
		infoPtr->readFlags |= CONSOLE_EOF;
		return 1;
	    }

	    /*
	     * Ignore errors if there is data in the buffer.
	     */
	    
	    if (infoPtr->readFlags & CONSOLE_BUFFERED) {
		return 0;
	    } else {
		return -1;
	    }
	}

	/*
	 * If there is data in the buffer, the console must be
	 * readable (since it is a line-oriented device).
	 */

	if (infoPtr->readFlags & CONSOLE_BUFFERED) {
	    return 1;
	}

	
	/*
	 * There wasn't any data available, so reset the thread and
	 * try again.
	 */
    
	ResetEvent(infoPtr->readable);
	SetEvent(infoPtr->startReader);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleReaderThread --
 *
 *	This function runs in a separate thread and waits for input
 *	to become available on a console.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Signals the main thread when input become available.  May
 *	cause the main thread to wake up by posting a message.  May
 *	one line from the console for each wait operation.
 *
 *----------------------------------------------------------------------
 */

static DWORD WINAPI
ConsoleReaderThread(LPVOID arg)
{
    ConsoleInfo *infoPtr = (ConsoleInfo *)arg;
    HANDLE *handle = infoPtr->handle;
    DWORD count, waitResult;
    HANDLE wEvents[2];

    /* The first event takes precedence. */
    wEvents[0] = infoPtr->stopReader;
    wEvents[1] = infoPtr->startReader;

    for (;;) {
	/*
	 * Wait for the main thread to signal before attempting to wait.
	 */

	waitResult = WaitForMultipleObjects(2, wEvents, FALSE, INFINITE);

	if (waitResult != (WAIT_OBJECT_0 + 1)) {
	    /*
	     * The start event was not signaled.  It must be the stop event
	     * or an error, so exit this thread.
	     */

	    break;
	}

	count = 0;

	/* 
	 * Look for data on the console, but first ignore any events
	 * that are not KEY_EVENTs 
	 */
	if (ReadConsoleA(handle, infoPtr->buffer, CONSOLE_BUFFER_SIZE,
		(LPDWORD) &infoPtr->bytesRead, NULL) != FALSE) {
	    /*
	     * Data was stored in the buffer.
	     */
	    
	    infoPtr->readFlags |= CONSOLE_BUFFERED;
	} else {
	    DWORD err;
	    err = GetLastError();
	    
	    if (err == EOF) {
		infoPtr->readFlags = CONSOLE_EOF;
	    }
	}

	/*
	 * Signal the main thread by signalling the readable event and
	 * then waking up the notifier thread.
	 */

	SetEvent(infoPtr->readable);

	/*
	 * Alert the foreground thread.  Note that we need to treat this like
	 * a critical section so the foreground thread does not terminate
	 * this thread while we are holding a mutex in the notifier code.
	 */

	Tcl_MutexLock(&consoleMutex);
	if (infoPtr->threadId != NULL) {
	    /* TIP #218. When in flight ignore the event, no one will receive it anyway */
	    Tcl_ThreadAlert(infoPtr->threadId);
	}
	Tcl_MutexUnlock(&consoleMutex);
    }

    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleWriterThread --
 *
 *	This function runs in a separate thread and writes data
 *	onto a console.
 *
 * Results:
 *	Always returns 0.
 *
 * Side effects:
 *	Signals the main thread when an output operation is completed.
 *	May cause the main thread to wake up by posting a message.  
 *
 *----------------------------------------------------------------------
 */

static DWORD WINAPI
ConsoleWriterThread(LPVOID arg)
{

    ConsoleInfo *infoPtr = (ConsoleInfo *)arg;
    HANDLE *handle = infoPtr->handle;
    DWORD count, toWrite, waitResult;
    char *buf;
    HANDLE wEvents[2];

    /* The first event takes precedence. */
    wEvents[0] = infoPtr->stopWriter;
    wEvents[1] = infoPtr->startWriter;

    for (;;) {
	/*
	 * Wait for the main thread to signal before attempting to write.
	 */

	waitResult = WaitForMultipleObjects(2, wEvents, FALSE, INFINITE);

	if (waitResult != (WAIT_OBJECT_0 + 1)) {
	    /*
	     * The start event was not signaled.  It must be the stop event
	     * or an error, so exit this thread.
	     */

	    break;
	}

	buf = infoPtr->writeBuf;
	toWrite = infoPtr->toWrite;

	/*
	 * Loop until all of the bytes are written or an error occurs.
	 */

	while (toWrite > 0) {
	    if (WriteConsole(handle, buf, toWrite, &count, NULL) == FALSE) {
		infoPtr->writeError = GetLastError();
		break;
	    } else {
		toWrite -= count;
		buf += count;
	    }
	}

	/*
	 * Signal the main thread by signalling the writable event and
	 * then waking up the notifier thread.
	 */
	
	SetEvent(infoPtr->writable);

	/*
	 * Alert the foreground thread.  Note that we need to treat this like
	 * a critical section so the foreground thread does not terminate
	 * this thread while we are holding a mutex in the notifier code.
	 */

	Tcl_MutexLock(&consoleMutex);
	if (infoPtr->threadId != NULL) {
	    /* TIP #218. When in flight ignore the event, no one will receive it anyway */
	    Tcl_ThreadAlert(infoPtr->threadId);
	}
	Tcl_MutexUnlock(&consoleMutex);
    }

    return 0;
}



/*
 *----------------------------------------------------------------------
 *
 * TclWinOpenConsoleChannel --
 *
 *	Constructs a Console channel for the specified standard OS handle.
 *      This is a helper function to break up the construction of 
 *      channels into File, Console, or Serial.
 *
 * Results:
 *	Returns the new channel, or NULL.
 *
 * Side effects:
 *	May open the channel
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
TclWinOpenConsoleChannel(handle, channelName, permissions)
    HANDLE handle;
    char *channelName;
    int permissions;
{
    char encoding[4 + TCL_INTEGER_SPACE];
    ConsoleInfo *infoPtr;
    DWORD id, modes;

    ConsoleInit();

    /*
     * See if a channel with this handle already exists.
     */
    
    infoPtr = (ConsoleInfo *) ckalloc((unsigned) sizeof(ConsoleInfo));
    memset(infoPtr, 0, sizeof(ConsoleInfo));

    infoPtr->validMask = permissions;
    infoPtr->handle = handle;
    infoPtr->channel = (Tcl_Channel) NULL;

    wsprintfA(encoding, "cp%d", GetConsoleCP());

    infoPtr->threadId = Tcl_GetCurrentThread();

    /*
     * Use the pointer for the name of the result channel.
     * This keeps the channel names unique, since some may share
     * handles (stdin/stdout/stderr for instance).
     */

    wsprintfA(channelName, "file%lx", (int) infoPtr);
    
    infoPtr->channel = Tcl_CreateChannel(&consoleChannelType, channelName,
            (ClientData) infoPtr, permissions);

    if (permissions & TCL_READABLE) {
	/*
	 * Make sure the console input buffer is ready for only character
	 * input notifications and the buffer is set for line buffering.
	 * IOW, we only want to catch when complete lines are ready for
	 * reading.
	 */
	GetConsoleMode(infoPtr->handle, &modes);
	modes &= ~(ENABLE_WINDOW_INPUT | ENABLE_MOUSE_INPUT);
	modes |= ENABLE_LINE_INPUT;
	SetConsoleMode(infoPtr->handle, modes);

	infoPtr->readable = CreateEvent(NULL, TRUE, TRUE, NULL);
	infoPtr->startReader = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->stopReader = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->readThread = CreateThread(NULL, 256, ConsoleReaderThread,
	        infoPtr, 0, &id);
	SetThreadPriority(infoPtr->readThread, THREAD_PRIORITY_HIGHEST);
    }

    if (permissions & TCL_WRITABLE) {
	infoPtr->writable = CreateEvent(NULL, TRUE, TRUE, NULL);
	infoPtr->startWriter = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->stopWriter = CreateEvent(NULL, FALSE, FALSE, NULL);
	infoPtr->writeThread = CreateThread(NULL, 256, ConsoleWriterThread,
	        infoPtr, 0, &id);
	SetThreadPriority(infoPtr->writeThread, THREAD_PRIORITY_HIGHEST);
    }

    /*
     * Files have default translation of AUTO and ^Z eof char, which
     * means that a ^Z will be accepted as EOF when reading.
     */
    
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-translation", "auto");
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-eofchar", "\032 {}");
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-encoding", encoding);

    return infoPtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * ConsoleThreadActionProc --
 *
 *	Insert or remove any thread local refs to this channel.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Changes thread local list of valid channels.
 *
 *----------------------------------------------------------------------
 */

static void
ConsoleThreadActionProc (instanceData, action)
     ClientData instanceData;
     int action;
{
    ConsoleInfo *infoPtr = (ConsoleInfo *) instanceData;

    /* We do not access firstConsolePtr in the thread structures. This is
     * not for all serials managed by the thread, but only those we are
     * watching. Removal of the filevent handlers before transfer thus
     * takes care of this structure.
     */

    Tcl_MutexLock(&consoleMutex);
    if (action == TCL_CHANNEL_THREAD_INSERT) {
        /* We can't copy the thread information from the channel when
	 * the channel is created. At this time the channel back
	 * pointer has not been set yet. However in that case the
	 * threadId has already been set by TclpCreateCommandChannel
	 * itself, so the structure is still good.
	 */

        ConsoleInit ();
        if (infoPtr->channel != NULL) {
	    infoPtr->threadId = Tcl_GetChannelThread (infoPtr->channel);
	}
    } else {
	infoPtr->threadId = NULL;
    }
    Tcl_MutexUnlock(&consoleMutex);
}