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