34292b1d |
1 | /* |
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. |
6 | * |
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. |
12 | * |
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 |
18 | * when one completes. |
8e32bfe0 |
19 | * |
20 | * (It's terribly annoying having to spawn a subthread for each |
21 | * direction of each handle. Technically it isn't necessary for |
22 | * serial ports, since we could use overlapped I/O within the main |
23 | * thread and wait directly on the event objects in the OVERLAPPED |
24 | * structures. However, we can't use this trick for some types of |
25 | * file handle at all - for some reason Windows restricts use of |
26 | * OVERLAPPED to files which were opened with the overlapped flag - |
27 | * and so we must use threads for those. This being the case, it's |
28 | * simplest just to use threads for everything rather than trying |
29 | * to keep track of multiple completely separate mechanisms.) |
34292b1d |
30 | */ |
31 | |
34292b1d |
32 | #include <assert.h> |
33 | |
34 | #include "putty.h" |
35 | |
36 | /* ---------------------------------------------------------------------- |
37 | * Generic definitions. |
38 | */ |
39 | |
40 | /* |
41 | * Maximum amount of backlog we will allow to build up on an input |
42 | * handle before we stop reading from it. |
43 | */ |
44 | #define MAX_BACKLOG 32768 |
45 | |
46 | struct handle_generic { |
47 | /* |
48 | * Initial fields common to both handle_input and handle_output |
49 | * structures. |
50 | * |
51 | * The three HANDLEs are set up at initialisation time and are |
52 | * thereafter read-only to both main thread and subthread. |
53 | * `moribund' is only used by the main thread; `done' is |
54 | * written by the main thread before signalling to the |
55 | * subthread. `defunct' and `busy' are used only by the main |
56 | * thread. |
57 | */ |
58 | HANDLE h; /* the handle itself */ |
59 | HANDLE ev_to_main; /* event used to signal main thread */ |
60 | HANDLE ev_from_main; /* event used to signal back to us */ |
61 | int moribund; /* are we going to kill this soon? */ |
62 | int done; /* request subthread to terminate */ |
63 | int defunct; /* has the subthread already gone? */ |
64 | int busy; /* operation currently in progress? */ |
0e03ceff |
65 | void *privdata; /* for client to remember who they are */ |
34292b1d |
66 | }; |
67 | |
68 | /* ---------------------------------------------------------------------- |
69 | * Input threads. |
70 | */ |
71 | |
72 | /* |
73 | * Data required by an input thread. |
74 | */ |
75 | struct handle_input { |
76 | /* |
77 | * Copy of the handle_generic structure. |
78 | */ |
79 | HANDLE h; /* the handle itself */ |
80 | HANDLE ev_to_main; /* event used to signal main thread */ |
81 | HANDLE ev_from_main; /* event used to signal back to us */ |
82 | int moribund; /* are we going to kill this soon? */ |
83 | int done; /* request subthread to terminate */ |
84 | int defunct; /* has the subthread already gone? */ |
85 | int busy; /* operation currently in progress? */ |
0e03ceff |
86 | void *privdata; /* for client to remember who they are */ |
34292b1d |
87 | |
88 | /* |
bdebd7e9 |
89 | * Data set at initialisation and then read-only. |
90 | */ |
91 | int flags; |
92 | |
93 | /* |
34292b1d |
94 | * Data set by the input thread before signalling ev_to_main, |
95 | * and read by the main thread after receiving that signal. |
96 | */ |
97 | char buffer[4096]; /* the data read from the handle */ |
98 | DWORD len; /* how much data that was */ |
21ae394f |
99 | int readerr; /* lets us know about read errors */ |
34292b1d |
100 | |
101 | /* |
102 | * Callback function called by this module when data arrives on |
103 | * an input handle. |
104 | */ |
105 | handle_inputfn_t gotdata; |
106 | }; |
107 | |
108 | /* |
109 | * The actual thread procedure for an input thread. |
110 | */ |
111 | static DWORD WINAPI handle_input_threadfunc(void *param) |
112 | { |
113 | struct handle_input *ctx = (struct handle_input *) param; |
bdebd7e9 |
114 | OVERLAPPED ovl, *povl; |
758a1377 |
115 | HANDLE oev; |
21ae394f |
116 | int readret, readlen; |
bdebd7e9 |
117 | |
758a1377 |
118 | if (ctx->flags & HANDLE_FLAG_OVERLAPPED) { |
bdebd7e9 |
119 | povl = &ovl; |
758a1377 |
120 | oev = CreateEvent(NULL, TRUE, FALSE, NULL); |
121 | } else { |
bdebd7e9 |
122 | povl = NULL; |
758a1377 |
123 | } |
34292b1d |
124 | |
c606abbc |
125 | if (ctx->flags & HANDLE_FLAG_UNITBUFFER) |
126 | readlen = 1; |
127 | else |
128 | readlen = sizeof(ctx->buffer); |
129 | |
34292b1d |
130 | while (1) { |
758a1377 |
131 | if (povl) { |
bdebd7e9 |
132 | memset(povl, 0, sizeof(OVERLAPPED)); |
758a1377 |
133 | povl->hEvent = oev; |
134 | } |
21ae394f |
135 | readret = ReadFile(ctx->h, ctx->buffer,readlen, &ctx->len, povl); |
136 | if (!readret) |
137 | ctx->readerr = GetLastError(); |
138 | else |
139 | ctx->readerr = 0; |
140 | if (povl && !readret && ctx->readerr == ERROR_IO_PENDING) { |
758a1377 |
141 | WaitForSingleObject(povl->hEvent, INFINITE); |
21ae394f |
142 | readret = GetOverlappedResult(ctx->h, povl, &ctx->len, FALSE); |
143 | if (!readret) |
144 | ctx->readerr = GetLastError(); |
145 | else |
146 | ctx->readerr = 0; |
758a1377 |
147 | } |
bdebd7e9 |
148 | |
21ae394f |
149 | if (!readret) { |
425f5af2 |
150 | /* |
151 | * Windows apparently sends ERROR_BROKEN_PIPE when a |
152 | * pipe we're reading from is closed normally from the |
153 | * writing end. This is ludicrous; if that situation |
154 | * isn't a natural EOF, _nothing_ is. So if we get that |
155 | * particular error, we pretend it's EOF. |
156 | */ |
21ae394f |
157 | if (ctx->readerr == ERROR_BROKEN_PIPE) |
158 | ctx->readerr = 0; |
34292b1d |
159 | ctx->len = 0; |
425f5af2 |
160 | } |
34292b1d |
161 | |
21ae394f |
162 | if (readret && ctx->len == 0 && |
bdebd7e9 |
163 | (ctx->flags & HANDLE_FLAG_IGNOREEOF)) |
164 | continue; |
165 | |
34292b1d |
166 | SetEvent(ctx->ev_to_main); |
167 | |
168 | if (!ctx->len) |
169 | break; |
170 | |
171 | WaitForSingleObject(ctx->ev_from_main, INFINITE); |
172 | if (ctx->done) |
173 | break; /* main thread told us to shut down */ |
174 | } |
175 | |
758a1377 |
176 | if (povl) |
177 | CloseHandle(oev); |
178 | |
34292b1d |
179 | return 0; |
180 | } |
181 | |
182 | /* |
183 | * This is called after a succcessful read, or from the |
184 | * `unthrottle' function. It decides whether or not to begin a new |
185 | * read operation. |
186 | */ |
187 | static void handle_throttle(struct handle_input *ctx, int backlog) |
188 | { |
50ab783a |
189 | if (ctx->defunct) |
190 | return; |
34292b1d |
191 | |
192 | /* |
193 | * If there's a read operation already in progress, do nothing: |
194 | * when that completes, we'll come back here and be in a |
195 | * position to make a better decision. |
196 | */ |
197 | if (ctx->busy) |
198 | return; |
199 | |
200 | /* |
201 | * Otherwise, we must decide whether to start a new read based |
202 | * on the size of the backlog. |
203 | */ |
204 | if (backlog < MAX_BACKLOG) { |
205 | SetEvent(ctx->ev_from_main); |
206 | ctx->busy = TRUE; |
207 | } |
208 | } |
209 | |
210 | /* ---------------------------------------------------------------------- |
211 | * Output threads. |
212 | */ |
213 | |
214 | /* |
215 | * Data required by an output thread. |
216 | */ |
217 | struct handle_output { |
218 | /* |
219 | * Copy of the handle_generic structure. |
220 | */ |
221 | HANDLE h; /* the handle itself */ |
222 | HANDLE ev_to_main; /* event used to signal main thread */ |
223 | HANDLE ev_from_main; /* event used to signal back to us */ |
224 | int moribund; /* are we going to kill this soon? */ |
225 | int done; /* request subthread to terminate */ |
226 | int defunct; /* has the subthread already gone? */ |
227 | int busy; /* operation currently in progress? */ |
0e03ceff |
228 | void *privdata; /* for client to remember who they are */ |
34292b1d |
229 | |
230 | /* |
bdebd7e9 |
231 | * Data set at initialisation and then read-only. |
232 | */ |
233 | int flags; |
234 | |
235 | /* |
34292b1d |
236 | * Data set by the main thread before signalling ev_from_main, |
237 | * and read by the input thread after receiving that signal. |
238 | */ |
239 | char *buffer; /* the data to write */ |
240 | DWORD len; /* how much data there is */ |
241 | |
242 | /* |
243 | * Data set by the input thread before signalling ev_to_main, |
244 | * and read by the main thread after receiving that signal. |
245 | */ |
246 | DWORD lenwritten; /* how much data we actually wrote */ |
21ae394f |
247 | int writeerr; /* return value from WriteFile */ |
34292b1d |
248 | |
249 | /* |
250 | * Data only ever read or written by the main thread. |
251 | */ |
252 | bufchain queued_data; /* data still waiting to be written */ |
253 | |
254 | /* |
255 | * Callback function called when the backlog in the bufchain |
256 | * drops. |
257 | */ |
258 | handle_outputfn_t sentdata; |
259 | }; |
260 | |
261 | static DWORD WINAPI handle_output_threadfunc(void *param) |
262 | { |
263 | struct handle_output *ctx = (struct handle_output *) param; |
bdebd7e9 |
264 | OVERLAPPED ovl, *povl; |
ded2f78a |
265 | HANDLE oev; |
21ae394f |
266 | int writeret; |
bdebd7e9 |
267 | |
ded2f78a |
268 | if (ctx->flags & HANDLE_FLAG_OVERLAPPED) { |
bdebd7e9 |
269 | povl = &ovl; |
ded2f78a |
270 | oev = CreateEvent(NULL, TRUE, FALSE, NULL); |
271 | } else { |
bdebd7e9 |
272 | povl = NULL; |
ded2f78a |
273 | } |
34292b1d |
274 | |
275 | while (1) { |
276 | WaitForSingleObject(ctx->ev_from_main, INFINITE); |
277 | if (ctx->done) { |
278 | SetEvent(ctx->ev_to_main); |
279 | break; |
280 | } |
ded2f78a |
281 | if (povl) { |
bdebd7e9 |
282 | memset(povl, 0, sizeof(OVERLAPPED)); |
ded2f78a |
283 | povl->hEvent = oev; |
284 | } |
285 | |
21ae394f |
286 | writeret = WriteFile(ctx->h, ctx->buffer, ctx->len, |
287 | &ctx->lenwritten, povl); |
288 | if (!writeret) |
289 | ctx->writeerr = GetLastError(); |
290 | else |
291 | ctx->writeerr = 0; |
292 | if (povl && !writeret && GetLastError() == ERROR_IO_PENDING) { |
293 | writeret = GetOverlappedResult(ctx->h, povl, |
294 | &ctx->lenwritten, TRUE); |
295 | if (!writeret) |
296 | ctx->writeerr = GetLastError(); |
297 | else |
298 | ctx->writeerr = 0; |
299 | } |
bdebd7e9 |
300 | |
34292b1d |
301 | SetEvent(ctx->ev_to_main); |
21ae394f |
302 | if (!writeret) |
34292b1d |
303 | break; |
304 | } |
305 | |
ded2f78a |
306 | if (povl) |
307 | CloseHandle(oev); |
308 | |
34292b1d |
309 | return 0; |
310 | } |
311 | |
312 | static void handle_try_output(struct handle_output *ctx) |
313 | { |
314 | void *senddata; |
315 | int sendlen; |
316 | |
317 | if (!ctx->busy && bufchain_size(&ctx->queued_data)) { |
318 | bufchain_prefix(&ctx->queued_data, &senddata, &sendlen); |
319 | ctx->buffer = senddata; |
320 | ctx->len = sendlen; |
321 | SetEvent(ctx->ev_from_main); |
322 | ctx->busy = TRUE; |
323 | } |
324 | } |
325 | |
326 | /* ---------------------------------------------------------------------- |
327 | * Unified code handling both input and output threads. |
328 | */ |
329 | |
330 | struct handle { |
331 | int output; |
332 | union { |
333 | struct handle_generic g; |
334 | struct handle_input i; |
335 | struct handle_output o; |
336 | } u; |
337 | }; |
338 | |
339 | static tree234 *handles_by_evtomain; |
340 | |
341 | static int handle_cmp_evtomain(void *av, void *bv) |
342 | { |
343 | struct handle *a = (struct handle *)av; |
344 | struct handle *b = (struct handle *)bv; |
345 | |
346 | if ((unsigned)a->u.g.ev_to_main < (unsigned)b->u.g.ev_to_main) |
347 | return -1; |
348 | else if ((unsigned)a->u.g.ev_to_main > (unsigned)b->u.g.ev_to_main) |
349 | return +1; |
350 | else |
351 | return 0; |
352 | } |
353 | |
354 | static int handle_find_evtomain(void *av, void *bv) |
355 | { |
356 | HANDLE *a = (HANDLE *)av; |
357 | struct handle *b = (struct handle *)bv; |
358 | |
359 | if ((unsigned)*a < (unsigned)b->u.g.ev_to_main) |
360 | return -1; |
361 | else if ((unsigned)*a > (unsigned)b->u.g.ev_to_main) |
362 | return +1; |
363 | else |
364 | return 0; |
365 | } |
366 | |
0e03ceff |
367 | struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata, |
bdebd7e9 |
368 | void *privdata, int flags) |
34292b1d |
369 | { |
370 | struct handle *h = snew(struct handle); |
600f6499 |
371 | DWORD in_threadid; /* required for Win9x */ |
34292b1d |
372 | |
373 | h->output = FALSE; |
374 | h->u.i.h = handle; |
375 | h->u.i.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
376 | h->u.i.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
377 | h->u.i.gotdata = gotdata; |
34292b1d |
378 | h->u.i.defunct = FALSE; |
379 | h->u.i.moribund = FALSE; |
380 | h->u.i.done = FALSE; |
0e03ceff |
381 | h->u.i.privdata = privdata; |
bdebd7e9 |
382 | h->u.i.flags = flags; |
34292b1d |
383 | |
384 | if (!handles_by_evtomain) |
385 | handles_by_evtomain = newtree234(handle_cmp_evtomain); |
386 | add234(handles_by_evtomain, h); |
387 | |
388 | CreateThread(NULL, 0, handle_input_threadfunc, |
600f6499 |
389 | &h->u.i, 0, &in_threadid); |
2ceabd36 |
390 | h->u.i.busy = TRUE; |
34292b1d |
391 | |
392 | return h; |
393 | } |
394 | |
0e03ceff |
395 | struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata, |
bdebd7e9 |
396 | void *privdata, int flags) |
34292b1d |
397 | { |
398 | struct handle *h = snew(struct handle); |
600f6499 |
399 | DWORD out_threadid; /* required for Win9x */ |
34292b1d |
400 | |
401 | h->output = TRUE; |
402 | h->u.o.h = handle; |
403 | h->u.o.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
404 | h->u.o.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL); |
405 | h->u.o.busy = FALSE; |
406 | h->u.o.defunct = FALSE; |
407 | h->u.o.moribund = FALSE; |
408 | h->u.o.done = FALSE; |
0e03ceff |
409 | h->u.o.privdata = privdata; |
34292b1d |
410 | bufchain_init(&h->u.o.queued_data); |
411 | h->u.o.sentdata = sentdata; |
bdebd7e9 |
412 | h->u.o.flags = flags; |
34292b1d |
413 | |
414 | if (!handles_by_evtomain) |
415 | handles_by_evtomain = newtree234(handle_cmp_evtomain); |
416 | add234(handles_by_evtomain, h); |
417 | |
418 | CreateThread(NULL, 0, handle_output_threadfunc, |
ded2f78a |
419 | &h->u.o, 0, &out_threadid); |
34292b1d |
420 | |
421 | return h; |
422 | } |
423 | |
424 | int handle_write(struct handle *h, const void *data, int len) |
425 | { |
426 | assert(h->output); |
427 | bufchain_add(&h->u.o.queued_data, data, len); |
428 | handle_try_output(&h->u.o); |
429 | return bufchain_size(&h->u.o.queued_data); |
430 | } |
431 | |
432 | HANDLE *handle_get_events(int *nevents) |
433 | { |
434 | HANDLE *ret; |
435 | struct handle *h; |
436 | int i, n, size; |
437 | |
438 | /* |
439 | * Go through our tree counting the handle objects currently |
440 | * engaged in useful activity. |
441 | */ |
442 | ret = NULL; |
443 | n = size = 0; |
444 | if (handles_by_evtomain) { |
445 | for (i = 0; (h = index234(handles_by_evtomain, i)) != NULL; i++) { |
446 | if (h->u.g.busy) { |
447 | if (n >= size) { |
448 | size += 32; |
449 | ret = sresize(ret, size, HANDLE); |
450 | } |
451 | ret[n++] = h->u.g.ev_to_main; |
452 | } |
453 | } |
454 | } |
455 | |
456 | *nevents = n; |
457 | return ret; |
458 | } |
459 | |
460 | static void handle_destroy(struct handle *h) |
461 | { |
462 | if (h->output) |
463 | bufchain_clear(&h->u.o.queued_data); |
464 | CloseHandle(h->u.g.ev_from_main); |
465 | CloseHandle(h->u.g.ev_to_main); |
466 | del234(handles_by_evtomain, h); |
467 | sfree(h); |
468 | } |
469 | |
470 | void handle_free(struct handle *h) |
471 | { |
472 | /* |
473 | * If the handle is currently busy, we cannot immediately free |
474 | * it. Instead we must wait until it's finished its current |
475 | * operation, because otherwise the subthread will write to |
476 | * invalid memory after we free its context from under it. |
477 | */ |
478 | assert(h && !h->u.g.moribund); |
479 | if (h->u.g.busy) { |
480 | /* |
481 | * Just set the moribund flag, which will be noticed next |
482 | * time an operation completes. |
483 | */ |
484 | h->u.g.moribund = TRUE; |
485 | } else if (h->u.g.defunct) { |
486 | /* |
487 | * There isn't even a subthread; we can go straight to |
488 | * handle_destroy. |
489 | */ |
490 | handle_destroy(h); |
491 | } else { |
492 | /* |
493 | * The subthread is alive but not busy, so we now signal it |
494 | * to die. Set the moribund flag to indicate that it will |
495 | * want destroying after that. |
496 | */ |
497 | h->u.g.moribund = TRUE; |
498 | h->u.g.done = TRUE; |
c969e831 |
499 | h->u.g.busy = TRUE; |
34292b1d |
500 | SetEvent(h->u.g.ev_from_main); |
501 | } |
502 | } |
503 | |
504 | void handle_got_event(HANDLE event) |
505 | { |
506 | struct handle *h; |
507 | |
508 | assert(handles_by_evtomain); |
509 | h = find234(handles_by_evtomain, &event, handle_find_evtomain); |
510 | if (!h) { |
511 | /* |
512 | * This isn't an error condition. If two or more event |
513 | * objects were signalled during the same select operation, |
514 | * and processing of the first caused the second handle to |
515 | * be closed, then it will sometimes happen that we receive |
516 | * an event notification here for a handle which is already |
517 | * deceased. In that situation we simply do nothing. |
518 | */ |
519 | return; |
520 | } |
521 | |
522 | if (h->u.g.moribund) { |
523 | /* |
524 | * A moribund handle is already treated as dead from the |
525 | * external user's point of view, so do nothing with the |
526 | * actual event. Just signal the thread to die if |
527 | * necessary, or destroy the handle if not. |
528 | */ |
529 | if (h->u.g.done) { |
530 | handle_destroy(h); |
531 | } else { |
532 | h->u.g.done = TRUE; |
c969e831 |
533 | h->u.g.busy = TRUE; |
34292b1d |
534 | SetEvent(h->u.g.ev_from_main); |
535 | } |
536 | return; |
537 | } |
538 | |
539 | if (!h->output) { |
540 | int backlog; |
541 | |
542 | h->u.i.busy = FALSE; |
543 | |
544 | /* |
545 | * A signal on an input handle means data has arrived. |
546 | */ |
547 | if (h->u.i.len == 0) { |
548 | /* |
549 | * EOF, or (nearly equivalently) read error. |
550 | */ |
21ae394f |
551 | h->u.i.gotdata(h, NULL, -h->u.i.readerr); |
34292b1d |
552 | h->u.i.defunct = TRUE; |
553 | } else { |
554 | backlog = h->u.i.gotdata(h, h->u.i.buffer, h->u.i.len); |
555 | handle_throttle(&h->u.i, backlog); |
556 | } |
557 | } else { |
558 | h->u.o.busy = FALSE; |
559 | |
560 | /* |
561 | * A signal on an output handle means we have completed a |
562 | * write. Call the callback to indicate that the output |
563 | * buffer size has decreased, or to indicate an error. |
564 | */ |
21ae394f |
565 | if (h->u.o.writeerr) { |
34292b1d |
566 | /* |
567 | * Write error. Send a negative value to the callback, |
568 | * and mark the thread as defunct (because the output |
569 | * thread is terminating by now). |
570 | */ |
21ae394f |
571 | h->u.o.sentdata(h, -h->u.o.writeerr); |
34292b1d |
572 | h->u.o.defunct = TRUE; |
573 | } else { |
574 | bufchain_consume(&h->u.o.queued_data, h->u.o.lenwritten); |
575 | h->u.o.sentdata(h, bufchain_size(&h->u.o.queued_data)); |
576 | handle_try_output(&h->u.o); |
577 | } |
578 | } |
579 | } |
580 | |
581 | void handle_unthrottle(struct handle *h, int backlog) |
582 | { |
583 | assert(!h->output); |
584 | handle_throttle(&h->u.i, backlog); |
585 | } |
586 | |
587 | int handle_backlog(struct handle *h) |
588 | { |
589 | assert(h->output); |
590 | return bufchain_size(&h->u.o.queued_data); |
591 | } |
0e03ceff |
592 | |
593 | void *handle_get_privdata(struct handle *h) |
594 | { |
595 | return h->u.g.privdata; |
596 | } |