2 * winhandl.c: Module to give Windows front ends the general
3 * ability to deal with consoles, pipes, serial ports, or any other
4 * type of data stream accessed through a Windows API HANDLE rather
5 * than a WinSock SOCKET.
7 * We do this by spawning a subthread to continuously try to read
8 * from the handle. Every time a read successfully returns some
9 * data, the subthread sets an event object which is picked up by
10 * the main thread, and the main thread then sets an event in
11 * return to instruct the subthread to resume reading.
13 * Output works precisely the other way round, in a second
14 * subthread. The output subthread should not be attempting to
15 * write all the time, because it hasn't always got data _to_
16 * write; so the output thread waits for an event object notifying
17 * it to _attempt_ a write, and then it sets an event in return
25 /* ----------------------------------------------------------------------
26 * Generic definitions.
30 * Maximum amount of backlog we will allow to build up on an input
31 * handle before we stop reading from it.
33 #define MAX_BACKLOG 32768
35 struct handle_generic
{
37 * Initial fields common to both handle_input and handle_output
40 * The three HANDLEs are set up at initialisation time and are
41 * thereafter read-only to both main thread and subthread.
42 * `moribund' is only used by the main thread; `done' is
43 * written by the main thread before signalling to the
44 * subthread. `defunct' and `busy' are used only by the main
47 HANDLE h
; /* the handle itself */
48 HANDLE ev_to_main
; /* event used to signal main thread */
49 HANDLE ev_from_main
; /* event used to signal back to us */
50 int moribund
; /* are we going to kill this soon? */
51 int done
; /* request subthread to terminate */
52 int defunct
; /* has the subthread already gone? */
53 int busy
; /* operation currently in progress? */
54 void *privdata
; /* for client to remember who they are */
57 /* ----------------------------------------------------------------------
62 * Data required by an input thread.
66 * Copy of the handle_generic structure.
68 HANDLE h
; /* the handle itself */
69 HANDLE ev_to_main
; /* event used to signal main thread */
70 HANDLE ev_from_main
; /* event used to signal back to us */
71 int moribund
; /* are we going to kill this soon? */
72 int done
; /* request subthread to terminate */
73 int defunct
; /* has the subthread already gone? */
74 int busy
; /* operation currently in progress? */
75 void *privdata
; /* for client to remember who they are */
78 * Data set at initialisation and then read-only.
83 * Data set by the input thread before signalling ev_to_main,
84 * and read by the main thread after receiving that signal.
86 char buffer
[4096]; /* the data read from the handle */
87 DWORD len
; /* how much data that was */
88 int readret
; /* lets us know about read errors */
91 * Callback function called by this module when data arrives on
94 handle_inputfn_t gotdata
;
98 * The actual thread procedure for an input thread.
100 static DWORD WINAPI
handle_input_threadfunc(void *param
)
102 struct handle_input
*ctx
= (struct handle_input
*) param
;
103 OVERLAPPED ovl
, *povl
;
107 if (ctx
->flags
& HANDLE_FLAG_OVERLAPPED
) {
109 oev
= CreateEvent(NULL
, TRUE
, FALSE
, NULL
);
114 if (ctx
->flags
& HANDLE_FLAG_UNITBUFFER
)
117 readlen
= sizeof(ctx
->buffer
);
121 memset(povl
, 0, sizeof(OVERLAPPED
));
124 ctx
->readret
= ReadFile(ctx
->h
, ctx
->buffer
, readlen
,
126 if (povl
&& !ctx
->readret
&& GetLastError() == ERROR_IO_PENDING
) {
127 WaitForSingleObject(povl
->hEvent
, INFINITE
);
128 ctx
->readret
= GetOverlappedResult(ctx
->h
, povl
, &ctx
->len
, FALSE
);
134 if (ctx
->readret
&& ctx
->len
== 0 &&
135 (ctx
->flags
& HANDLE_FLAG_IGNOREEOF
))
138 SetEvent(ctx
->ev_to_main
);
143 WaitForSingleObject(ctx
->ev_from_main
, INFINITE
);
145 break; /* main thread told us to shut down */
155 * This is called after a succcessful read, or from the
156 * `unthrottle' function. It decides whether or not to begin a new
159 static void handle_throttle(struct handle_input
*ctx
, int backlog
)
165 * If there's a read operation already in progress, do nothing:
166 * when that completes, we'll come back here and be in a
167 * position to make a better decision.
173 * Otherwise, we must decide whether to start a new read based
174 * on the size of the backlog.
176 if (backlog
< MAX_BACKLOG
) {
177 SetEvent(ctx
->ev_from_main
);
182 /* ----------------------------------------------------------------------
187 * Data required by an output thread.
189 struct handle_output
{
191 * Copy of the handle_generic structure.
193 HANDLE h
; /* the handle itself */
194 HANDLE ev_to_main
; /* event used to signal main thread */
195 HANDLE ev_from_main
; /* event used to signal back to us */
196 int moribund
; /* are we going to kill this soon? */
197 int done
; /* request subthread to terminate */
198 int defunct
; /* has the subthread already gone? */
199 int busy
; /* operation currently in progress? */
200 void *privdata
; /* for client to remember who they are */
203 * Data set at initialisation and then read-only.
208 * Data set by the main thread before signalling ev_from_main,
209 * and read by the input thread after receiving that signal.
211 char *buffer
; /* the data to write */
212 DWORD len
; /* how much data there is */
215 * Data set by the input thread before signalling ev_to_main,
216 * and read by the main thread after receiving that signal.
218 DWORD lenwritten
; /* how much data we actually wrote */
219 int writeret
; /* return value from WriteFile */
222 * Data only ever read or written by the main thread.
224 bufchain queued_data
; /* data still waiting to be written */
227 * Callback function called when the backlog in the bufchain
230 handle_outputfn_t sentdata
;
233 static DWORD WINAPI
handle_output_threadfunc(void *param
)
235 struct handle_output
*ctx
= (struct handle_output
*) param
;
236 OVERLAPPED ovl
, *povl
;
238 if (ctx
->flags
& HANDLE_FLAG_OVERLAPPED
)
244 WaitForSingleObject(ctx
->ev_from_main
, INFINITE
);
246 SetEvent(ctx
->ev_to_main
);
250 memset(povl
, 0, sizeof(OVERLAPPED
));
251 ctx
->writeret
= WriteFile(ctx
->h
, ctx
->buffer
, ctx
->len
,
252 &ctx
->lenwritten
, povl
);
253 if (povl
&& !ctx
->writeret
&& GetLastError() == ERROR_IO_PENDING
)
254 ctx
->writeret
= GetOverlappedResult(ctx
->h
, povl
,
255 &ctx
->lenwritten
, TRUE
);
257 SetEvent(ctx
->ev_to_main
);
265 static void handle_try_output(struct handle_output
*ctx
)
270 if (!ctx
->busy
&& bufchain_size(&ctx
->queued_data
)) {
271 bufchain_prefix(&ctx
->queued_data
, &senddata
, &sendlen
);
272 ctx
->buffer
= senddata
;
274 SetEvent(ctx
->ev_from_main
);
279 /* ----------------------------------------------------------------------
280 * Unified code handling both input and output threads.
286 struct handle_generic g
;
287 struct handle_input i
;
288 struct handle_output o
;
292 static tree234
*handles_by_evtomain
;
294 static int handle_cmp_evtomain(void *av
, void *bv
)
296 struct handle
*a
= (struct handle
*)av
;
297 struct handle
*b
= (struct handle
*)bv
;
299 if ((unsigned)a
->u
.g
.ev_to_main
< (unsigned)b
->u
.g
.ev_to_main
)
301 else if ((unsigned)a
->u
.g
.ev_to_main
> (unsigned)b
->u
.g
.ev_to_main
)
307 static int handle_find_evtomain(void *av
, void *bv
)
309 HANDLE
*a
= (HANDLE
*)av
;
310 struct handle
*b
= (struct handle
*)bv
;
312 if ((unsigned)*a
< (unsigned)b
->u
.g
.ev_to_main
)
314 else if ((unsigned)*a
> (unsigned)b
->u
.g
.ev_to_main
)
320 struct handle
*handle_input_new(HANDLE handle
, handle_inputfn_t gotdata
,
321 void *privdata
, int flags
)
323 struct handle
*h
= snew(struct handle
);
327 h
->u
.i
.ev_to_main
= CreateEvent(NULL
, FALSE
, FALSE
, NULL
);
328 h
->u
.i
.ev_from_main
= CreateEvent(NULL
, FALSE
, FALSE
, NULL
);
329 h
->u
.i
.gotdata
= gotdata
;
330 h
->u
.i
.defunct
= FALSE
;
331 h
->u
.i
.moribund
= FALSE
;
333 h
->u
.i
.privdata
= privdata
;
334 h
->u
.i
.flags
= flags
;
336 if (!handles_by_evtomain
)
337 handles_by_evtomain
= newtree234(handle_cmp_evtomain
);
338 add234(handles_by_evtomain
, h
);
340 CreateThread(NULL
, 0, handle_input_threadfunc
,
347 struct handle
*handle_output_new(HANDLE handle
, handle_outputfn_t sentdata
,
348 void *privdata
, int flags
)
350 struct handle
*h
= snew(struct handle
);
354 h
->u
.o
.ev_to_main
= CreateEvent(NULL
, FALSE
, FALSE
, NULL
);
355 h
->u
.o
.ev_from_main
= CreateEvent(NULL
, FALSE
, FALSE
, NULL
);
357 h
->u
.o
.defunct
= FALSE
;
358 h
->u
.o
.moribund
= FALSE
;
360 h
->u
.o
.privdata
= privdata
;
361 bufchain_init(&h
->u
.o
.queued_data
);
362 h
->u
.o
.sentdata
= sentdata
;
363 h
->u
.o
.flags
= flags
;
365 if (!handles_by_evtomain
)
366 handles_by_evtomain
= newtree234(handle_cmp_evtomain
);
367 add234(handles_by_evtomain
, h
);
369 CreateThread(NULL
, 0, handle_output_threadfunc
,
375 int handle_write(struct handle
*h
, const void *data
, int len
)
378 bufchain_add(&h
->u
.o
.queued_data
, data
, len
);
379 handle_try_output(&h
->u
.o
);
380 return bufchain_size(&h
->u
.o
.queued_data
);
383 HANDLE
*handle_get_events(int *nevents
)
390 * Go through our tree counting the handle objects currently
391 * engaged in useful activity.
395 if (handles_by_evtomain
) {
396 for (i
= 0; (h
= index234(handles_by_evtomain
, i
)) != NULL
; i
++) {
400 ret
= sresize(ret
, size
, HANDLE
);
402 ret
[n
++] = h
->u
.g
.ev_to_main
;
411 static void handle_destroy(struct handle
*h
)
414 bufchain_clear(&h
->u
.o
.queued_data
);
415 CloseHandle(h
->u
.g
.ev_from_main
);
416 CloseHandle(h
->u
.g
.ev_to_main
);
417 del234(handles_by_evtomain
, h
);
421 void handle_free(struct handle
*h
)
424 * If the handle is currently busy, we cannot immediately free
425 * it. Instead we must wait until it's finished its current
426 * operation, because otherwise the subthread will write to
427 * invalid memory after we free its context from under it.
429 assert(h
&& !h
->u
.g
.moribund
);
432 * Just set the moribund flag, which will be noticed next
433 * time an operation completes.
435 h
->u
.g
.moribund
= TRUE
;
436 } else if (h
->u
.g
.defunct
) {
438 * There isn't even a subthread; we can go straight to
444 * The subthread is alive but not busy, so we now signal it
445 * to die. Set the moribund flag to indicate that it will
446 * want destroying after that.
448 h
->u
.g
.moribund
= TRUE
;
451 SetEvent(h
->u
.g
.ev_from_main
);
455 void handle_got_event(HANDLE event
)
459 assert(handles_by_evtomain
);
460 h
= find234(handles_by_evtomain
, &event
, handle_find_evtomain
);
463 * This isn't an error condition. If two or more event
464 * objects were signalled during the same select operation,
465 * and processing of the first caused the second handle to
466 * be closed, then it will sometimes happen that we receive
467 * an event notification here for a handle which is already
468 * deceased. In that situation we simply do nothing.
473 if (h
->u
.g
.moribund
) {
475 * A moribund handle is already treated as dead from the
476 * external user's point of view, so do nothing with the
477 * actual event. Just signal the thread to die if
478 * necessary, or destroy the handle if not.
485 SetEvent(h
->u
.g
.ev_from_main
);
496 * A signal on an input handle means data has arrived.
498 if (h
->u
.i
.len
== 0) {
500 * EOF, or (nearly equivalently) read error.
502 h
->u
.i
.gotdata(h
, NULL
, (h
->u
.i
.readret ?
0 : -1));
503 h
->u
.i
.defunct
= TRUE
;
505 backlog
= h
->u
.i
.gotdata(h
, h
->u
.i
.buffer
, h
->u
.i
.len
);
506 handle_throttle(&h
->u
.i
, backlog
);
512 * A signal on an output handle means we have completed a
513 * write. Call the callback to indicate that the output
514 * buffer size has decreased, or to indicate an error.
516 if (!h
->u
.o
.writeret
) {
518 * Write error. Send a negative value to the callback,
519 * and mark the thread as defunct (because the output
520 * thread is terminating by now).
522 h
->u
.o
.sentdata(h
, -1);
523 h
->u
.o
.defunct
= TRUE
;
525 bufchain_consume(&h
->u
.o
.queued_data
, h
->u
.o
.lenwritten
);
526 h
->u
.o
.sentdata(h
, bufchain_size(&h
->u
.o
.queued_data
));
527 handle_try_output(&h
->u
.o
);
532 void handle_unthrottle(struct handle
*h
, int backlog
)
535 handle_throttle(&h
->u
.i
, backlog
);
538 int handle_backlog(struct handle
*h
)
541 return bufchain_size(&h
->u
.o
.queued_data
);
544 void *handle_get_privdata(struct handle
*h
)
546 return h
->u
.g
.privdata
;