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