| blob | dbcab2b2a7e20ea7d504766a64be0b5c6dd3a313 |
1 /*\r
2 * winhandl.c: Module to give Windows front ends the general\r
3 * ability to deal with consoles, pipes, serial ports, or any other\r
4 * type of data stream accessed through a Windows API HANDLE rather\r
5 * than a WinSock SOCKET.\r
6 *\r
7 * We do this by spawning a subthread to continuously try to read\r
8 * from the handle. Every time a read successfully returns some\r
9 * data, the subthread sets an event object which is picked up by\r
10 * the main thread, and the main thread then sets an event in\r
11 * return to instruct the subthread to resume reading.\r
12 * \r
13 * Output works precisely the other way round, in a second\r
14 * subthread. The output subthread should not be attempting to\r
15 * write all the time, because it hasn't always got data _to_\r
16 * write; so the output thread waits for an event object notifying\r
17 * it to _attempt_ a write, and then it sets an event in return\r
18 * when one completes.\r
19 * \r
20 * (It's terribly annoying having to spawn a subthread for each\r
21 * direction of each handle. Technically it isn't necessary for\r
22 * serial ports, since we could use overlapped I/O within the main\r
23 * thread and wait directly on the event objects in the OVERLAPPED\r
24 * structures. However, we can't use this trick for some types of\r
25 * file handle at all - for some reason Windows restricts use of\r
26 * OVERLAPPED to files which were opened with the overlapped flag -\r
27 * and so we must use threads for those. This being the case, it's\r
28 * simplest just to use threads for everything rather than trying\r
29 * to keep track of multiple completely separate mechanisms.)\r
30 */\r
31 \r
32 #include <assert.h>\r
33 \r
34 #include "putty.h"\r
35 \r
36 /* ----------------------------------------------------------------------\r
37 * Generic definitions.\r
38 */\r
39 \r
40 /*\r
41 * Maximum amount of backlog we will allow to build up on an input\r
42 * handle before we stop reading from it.\r
43 */\r
44 #define MAX_BACKLOG 32768\r
45 \r
46 struct handle_generic {\r
47 /*\r
48 * Initial fields common to both handle_input and handle_output\r
49 * structures.\r
50 * \r
51 * The three HANDLEs are set up at initialisation time and are\r
52 * thereafter read-only to both main thread and subthread.\r
53 * `moribund' is only used by the main thread; `done' is\r
54 * written by the main thread before signalling to the\r
55 * subthread. `defunct' and `busy' are used only by the main\r
56 * thread.\r
57 */\r
58 HANDLE h; /* the handle itself */\r
59 HANDLE ev_to_main; /* event used to signal main thread */\r
60 HANDLE ev_from_main; /* event used to signal back to us */\r
61 int moribund; /* are we going to kill this soon? */\r
62 int done; /* request subthread to terminate */\r
63 int defunct; /* has the subthread already gone? */\r
64 int busy; /* operation currently in progress? */\r
65 void *privdata; /* for client to remember who they are */\r
66 };\r
67 \r
68 /* ----------------------------------------------------------------------\r
69 * Input threads.\r
70 */\r
71 \r
72 /*\r
73 * Data required by an input thread.\r
74 */\r
75 struct handle_input {\r
76 /*\r
77 * Copy of the handle_generic structure.\r
78 */\r
79 HANDLE h; /* the handle itself */\r
80 HANDLE ev_to_main; /* event used to signal main thread */\r
81 HANDLE ev_from_main; /* event used to signal back to us */\r
82 int moribund; /* are we going to kill this soon? */\r
83 int done; /* request subthread to terminate */\r
84 int defunct; /* has the subthread already gone? */\r
85 int busy; /* operation currently in progress? */\r
86 void *privdata; /* for client to remember who they are */\r
87 \r
88 /*\r
89 * Data set at initialisation and then read-only.\r
90 */\r
91 int flags;\r
92 \r
93 /*\r
94 * Data set by the input thread before signalling ev_to_main,\r
95 * and read by the main thread after receiving that signal.\r
96 */\r
97 char buffer[4096]; /* the data read from the handle */\r
98 DWORD len; /* how much data that was */\r
99 int readerr; /* lets us know about read errors */\r
100 \r
101 /*\r
102 * Callback function called by this module when data arrives on\r
103 * an input handle.\r
104 */\r
105 handle_inputfn_t gotdata;\r
106 };\r
107 \r
108 /*\r
109 * The actual thread procedure for an input thread.\r
110 */\r
111 static DWORD WINAPI handle_input_threadfunc(void *param)\r
112 {\r
113 struct handle_input *ctx = (struct handle_input *) param;\r
114 OVERLAPPED ovl, *povl;\r
115 HANDLE oev;\r
116 int readret, readlen;\r
117 \r
118 if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {\r
119 povl = &ovl;\r
120 oev = CreateEvent(NULL, TRUE, FALSE, NULL);\r
121 } else {\r
122 povl = NULL;\r
123 }\r
124 \r
125 if (ctx->flags & HANDLE_FLAG_UNITBUFFER)\r
126 readlen = 1;\r
127 else\r
128 readlen = sizeof(ctx->buffer);\r
129 \r
130 while (1) {\r
131 if (povl) {\r
132 memset(povl, 0, sizeof(OVERLAPPED));\r
133 povl->hEvent = oev;\r
134 }\r
135 readret = ReadFile(ctx->h, ctx->buffer,readlen, &ctx->len, povl);\r
136 if (!readret)\r
137 ctx->readerr = GetLastError();\r
138 else\r
139 ctx->readerr = 0;\r
140 if (povl && !readret && ctx->readerr == ERROR_IO_PENDING) {\r
141 WaitForSingleObject(povl->hEvent, INFINITE);\r
142 readret = GetOverlappedResult(ctx->h, povl, &ctx->len, FALSE);\r
143 if (!readret)\r
144 ctx->readerr = GetLastError();\r
145 else\r
146 ctx->readerr = 0;\r
147 }\r
148 \r
149 if (!readret) {\r
150 /*\r
151 * Windows apparently sends ERROR_BROKEN_PIPE when a\r
152 * pipe we're reading from is closed normally from the\r
153 * writing end. This is ludicrous; if that situation\r
154 * isn't a natural EOF, _nothing_ is. So if we get that\r
155 * particular error, we pretend it's EOF.\r
156 */\r
157 if (ctx->readerr == ERROR_BROKEN_PIPE)\r
158 ctx->readerr = 0;\r
159 ctx->len = 0;\r
160 }\r
161 \r
162 if (readret && ctx->len == 0 &&\r
163 (ctx->flags & HANDLE_FLAG_IGNOREEOF))\r
164 continue;\r
165 \r
166 SetEvent(ctx->ev_to_main);\r
167 \r
168 if (!ctx->len)\r
169 break;\r
170 \r
171 WaitForSingleObject(ctx->ev_from_main, INFINITE);\r
172 if (ctx->done)\r
173 break; /* main thread told us to shut down */\r
174 }\r
175 \r
176 if (povl)\r
177 CloseHandle(oev);\r
178 \r
179 return 0;\r
180 }\r
181 \r
182 /*\r
183 * This is called after a succcessful read, or from the\r
184 * `unthrottle' function. It decides whether or not to begin a new\r
185 * read operation.\r
186 */\r
187 static void handle_throttle(struct handle_input *ctx, int backlog)\r
188 {\r
189 if (ctx->defunct)\r
190 return;\r
191 \r
192 /*\r
193 * If there's a read operation already in progress, do nothing:\r
194 * when that completes, we'll come back here and be in a\r
195 * position to make a better decision.\r
196 */\r
197 if (ctx->busy)\r
198 return;\r
199 \r
200 /*\r
201 * Otherwise, we must decide whether to start a new read based\r
202 * on the size of the backlog.\r
203 */\r
204 if (backlog < MAX_BACKLOG) {\r
205 SetEvent(ctx->ev_from_main);\r
206 ctx->busy = TRUE;\r
207 }\r
208 }\r
209 \r
210 /* ----------------------------------------------------------------------\r
211 * Output threads.\r
212 */\r
213 \r
214 /*\r
215 * Data required by an output thread.\r
216 */\r
217 struct handle_output {\r
218 /*\r
219 * Copy of the handle_generic structure.\r
220 */\r
221 HANDLE h; /* the handle itself */\r
222 HANDLE ev_to_main; /* event used to signal main thread */\r
223 HANDLE ev_from_main; /* event used to signal back to us */\r
224 int moribund; /* are we going to kill this soon? */\r
225 int done; /* request subthread to terminate */\r
226 int defunct; /* has the subthread already gone? */\r
227 int busy; /* operation currently in progress? */\r
228 void *privdata; /* for client to remember who they are */\r
229 \r
230 /*\r
231 * Data set at initialisation and then read-only.\r
232 */\r
233 int flags;\r
234 \r
235 /*\r
236 * Data set by the main thread before signalling ev_from_main,\r
237 * and read by the input thread after receiving that signal.\r
238 */\r
239 char *buffer; /* the data to write */\r
240 DWORD len; /* how much data there is */\r
241 \r
242 /*\r
243 * Data set by the input thread before signalling ev_to_main,\r
244 * and read by the main thread after receiving that signal.\r
245 */\r
246 DWORD lenwritten; /* how much data we actually wrote */\r
247 int writeerr; /* return value from WriteFile */\r
248 \r
249 /*\r
250 * Data only ever read or written by the main thread.\r
251 */\r
252 bufchain queued_data; /* data still waiting to be written */\r
253 \r
254 /*\r
255 * Callback function called when the backlog in the bufchain\r
256 * drops.\r
257 */\r
258 handle_outputfn_t sentdata;\r
259 };\r
260 \r
261 static DWORD WINAPI handle_output_threadfunc(void *param)\r
262 {\r
263 struct handle_output *ctx = (struct handle_output *) param;\r
264 OVERLAPPED ovl, *povl;\r
265 HANDLE oev;\r
266 int writeret;\r
267 \r
268 if (ctx->flags & HANDLE_FLAG_OVERLAPPED) {\r
269 povl = &ovl;\r
270 oev = CreateEvent(NULL, TRUE, FALSE, NULL);\r
271 } else {\r
272 povl = NULL;\r
273 }\r
274 \r
275 while (1) {\r
276 WaitForSingleObject(ctx->ev_from_main, INFINITE);\r
277 if (ctx->done) {\r
278 SetEvent(ctx->ev_to_main);\r
279 break;\r
280 }\r
281 if (povl) {\r
282 memset(povl, 0, sizeof(OVERLAPPED));\r
283 povl->hEvent = oev;\r
284 }\r
285 \r
286 writeret = WriteFile(ctx->h, ctx->buffer, ctx->len,\r
287 &ctx->lenwritten, povl);\r
288 if (!writeret)\r
289 ctx->writeerr = GetLastError();\r
290 else\r
291 ctx->writeerr = 0;\r
292 if (povl && !writeret && GetLastError() == ERROR_IO_PENDING) {\r
293 writeret = GetOverlappedResult(ctx->h, povl,\r
294 &ctx->lenwritten, TRUE);\r
295 if (!writeret)\r
296 ctx->writeerr = GetLastError();\r
297 else\r
298 ctx->writeerr = 0;\r
299 }\r
300 \r
301 SetEvent(ctx->ev_to_main);\r
302 if (!writeret)\r
303 break;\r
304 }\r
305 \r
306 if (povl)\r
307 CloseHandle(oev);\r
308 \r
309 return 0;\r
310 }\r
311 \r
312 static void handle_try_output(struct handle_output *ctx)\r
313 {\r
314 void *senddata;\r
315 int sendlen;\r
316 \r
317 if (!ctx->busy && bufchain_size(&ctx->queued_data)) {\r
318 bufchain_prefix(&ctx->queued_data, &senddata, &sendlen);\r
319 ctx->buffer = senddata;\r
320 ctx->len = sendlen;\r
321 SetEvent(ctx->ev_from_main);\r
322 ctx->busy = TRUE;\r
323 }\r
324 }\r
325 \r
326 /* ----------------------------------------------------------------------\r
327 * Unified code handling both input and output threads.\r
328 */\r
329 \r
330 struct handle {\r
331 int output;\r
332 union {\r
333 struct handle_generic g;\r
334 struct handle_input i;\r
335 struct handle_output o;\r
336 } u;\r
337 };\r
338 \r
339 static tree234 *handles_by_evtomain;\r
340 \r
341 static int handle_cmp_evtomain(void *av, void *bv)\r
342 {\r
343 struct handle *a = (struct handle *)av;\r
344 struct handle *b = (struct handle *)bv;\r
345 \r
346 if ((unsigned)a->u.g.ev_to_main < (unsigned)b->u.g.ev_to_main)\r
347 return -1;\r
348 else if ((unsigned)a->u.g.ev_to_main > (unsigned)b->u.g.ev_to_main)\r
349 return +1;\r
350 else\r
351 return 0;\r
352 }\r
353 \r
354 static int handle_find_evtomain(void *av, void *bv)\r
355 {\r
356 HANDLE *a = (HANDLE *)av;\r
357 struct handle *b = (struct handle *)bv;\r
358 \r
359 if ((unsigned)*a < (unsigned)b->u.g.ev_to_main)\r
360 return -1;\r
361 else if ((unsigned)*a > (unsigned)b->u.g.ev_to_main)\r
362 return +1;\r
363 else\r
364 return 0;\r
365 }\r
366 \r
367 struct handle *handle_input_new(HANDLE handle, handle_inputfn_t gotdata,\r
368 void *privdata, int flags)\r
369 {\r
370 struct handle *h = snew(struct handle);\r
371 DWORD in_threadid; /* required for Win9x */\r
372 \r
373 h->output = FALSE;\r
374 h->u.i.h = handle;\r
375 h->u.i.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);\r
376 h->u.i.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);\r
377 h->u.i.gotdata = gotdata;\r
378 h->u.i.defunct = FALSE;\r
379 h->u.i.moribund = FALSE;\r
380 h->u.i.done = FALSE;\r
381 h->u.i.privdata = privdata;\r
382 h->u.i.flags = flags;\r
383 \r
384 if (!handles_by_evtomain)\r
385 handles_by_evtomain = newtree234(handle_cmp_evtomain);\r
386 add234(handles_by_evtomain, h);\r
387 \r
388 CreateThread(NULL, 0, handle_input_threadfunc,\r
389 &h->u.i, 0, &in_threadid);\r
390 h->u.i.busy = TRUE;\r
391 \r
392 return h;\r
393 }\r
394 \r
395 struct handle *handle_output_new(HANDLE handle, handle_outputfn_t sentdata,\r
396 void *privdata, int flags)\r
397 {\r
398 struct handle *h = snew(struct handle);\r
399 DWORD out_threadid; /* required for Win9x */\r
400 \r
401 h->output = TRUE;\r
402 h->u.o.h = handle;\r
403 h->u.o.ev_to_main = CreateEvent(NULL, FALSE, FALSE, NULL);\r
404 h->u.o.ev_from_main = CreateEvent(NULL, FALSE, FALSE, NULL);\r
405 h->u.o.busy = FALSE;\r
406 h->u.o.defunct = FALSE;\r
407 h->u.o.moribund = FALSE;\r
408 h->u.o.done = FALSE;\r
409 h->u.o.privdata = privdata;\r
410 bufchain_init(&h->u.o.queued_data);\r
411 h->u.o.sentdata = sentdata;\r
412 h->u.o.flags = flags;\r
413 \r
414 if (!handles_by_evtomain)\r
415 handles_by_evtomain = newtree234(handle_cmp_evtomain);\r
416 add234(handles_by_evtomain, h);\r
417 \r
418 CreateThread(NULL, 0, handle_output_threadfunc,\r
419 &h->u.o, 0, &out_threadid);\r
420 \r
421 return h;\r
422 }\r
423 \r
424 int handle_write(struct handle *h, const void *data, int len)\r
425 {\r
426 assert(h->output);\r
427 bufchain_add(&h->u.o.queued_data, data, len);\r
428 handle_try_output(&h->u.o);\r
429 return bufchain_size(&h->u.o.queued_data);\r
430 }\r
431 \r
432 HANDLE *handle_get_events(int *nevents)\r
433 {\r
434 HANDLE *ret;\r
435 struct handle *h;\r
436 int i, n, size;\r
437 \r
438 /*\r
439 * Go through our tree counting the handle objects currently\r
440 * engaged in useful activity.\r
441 */\r
442 ret = NULL;\r
443 n = size = 0;\r
444 if (handles_by_evtomain) {\r
445 for (i = 0; (h = index234(handles_by_evtomain, i)) != NULL; i++) {\r
446 if (h->u.g.busy) {\r
447 if (n >= size) {\r
448 size += 32;\r
449 ret = sresize(ret, size, HANDLE);\r
450 }\r
451 ret[n++] = h->u.g.ev_to_main;\r
452 }\r
453 }\r
454 }\r
455 \r
456 *nevents = n;\r
457 return ret;\r
458 }\r
459 \r
460 static void handle_destroy(struct handle *h)\r
461 {\r
462 if (h->output)\r
463 bufchain_clear(&h->u.o.queued_data);\r
464 CloseHandle(h->u.g.ev_from_main);\r
465 CloseHandle(h->u.g.ev_to_main);\r
466 del234(handles_by_evtomain, h);\r
467 sfree(h);\r
468 }\r
469 \r
470 void handle_free(struct handle *h)\r
471 {\r
472 /*\r
473 * If the handle is currently busy, we cannot immediately free\r
474 * it. Instead we must wait until it's finished its current\r
475 * operation, because otherwise the subthread will write to\r
476 * invalid memory after we free its context from under it.\r
477 */\r
478 assert(h && !h->u.g.moribund);\r
479 if (h->u.g.busy) {\r
480 /*\r
481 * Just set the moribund flag, which will be noticed next\r
482 * time an operation completes.\r
483 */\r
484 h->u.g.moribund = TRUE;\r
485 } else if (h->u.g.defunct) {\r
486 /*\r
487 * There isn't even a subthread; we can go straight to\r
488 * handle_destroy.\r
489 */\r
490 handle_destroy(h);\r
491 } else {\r
492 /*\r
493 * The subthread is alive but not busy, so we now signal it\r
494 * to die. Set the moribund flag to indicate that it will\r
495 * want destroying after that.\r
496 */\r
497 h->u.g.moribund = TRUE;\r
498 h->u.g.done = TRUE;\r
499 h->u.g.busy = TRUE;\r
500 SetEvent(h->u.g.ev_from_main);\r
501 }\r
502 }\r
503 \r
504 void handle_got_event(HANDLE event)\r
505 {\r
506 struct handle *h;\r
507 \r
508 assert(handles_by_evtomain);\r
509 h = find234(handles_by_evtomain, &event, handle_find_evtomain);\r
510 if (!h) {\r
511 /*\r
512 * This isn't an error condition. If two or more event\r
513 * objects were signalled during the same select operation,\r
514 * and processing of the first caused the second handle to\r
515 * be closed, then it will sometimes happen that we receive\r
516 * an event notification here for a handle which is already\r
517 * deceased. In that situation we simply do nothing.\r
518 */\r
519 return;\r
520 }\r
521 \r
522 if (h->u.g.moribund) {\r
523 /*\r
524 * A moribund handle is already treated as dead from the\r
525 * external user's point of view, so do nothing with the\r
526 * actual event. Just signal the thread to die if\r
527 * necessary, or destroy the handle if not.\r
528 */\r
529 if (h->u.g.done) {\r
530 handle_destroy(h);\r
531 } else {\r
532 h->u.g.done = TRUE;\r
533 h->u.g.busy = TRUE;\r
534 SetEvent(h->u.g.ev_from_main);\r
535 }\r
536 return;\r
537 }\r
538 \r
539 if (!h->output) {\r
540 int backlog;\r
541 \r
542 h->u.i.busy = FALSE;\r
543 \r
544 /*\r
545 * A signal on an input handle means data has arrived.\r
546 */\r
547 if (h->u.i.len == 0) {\r
548 /*\r
549 * EOF, or (nearly equivalently) read error.\r
550 */\r
551 h->u.i.gotdata(h, NULL, -h->u.i.readerr);\r
552 h->u.i.defunct = TRUE;\r
553 } else {\r
554 backlog = h->u.i.gotdata(h, h->u.i.buffer, h->u.i.len);\r
555 handle_throttle(&h->u.i, backlog);\r
556 }\r
557 } else {\r
558 h->u.o.busy = FALSE;\r
559 \r
560 /*\r
561 * A signal on an output handle means we have completed a\r
562 * write. Call the callback to indicate that the output\r
563 * buffer size has decreased, or to indicate an error.\r
564 */\r
565 if (h->u.o.writeerr) {\r
566 /*\r
567 * Write error. Send a negative value to the callback,\r
568 * and mark the thread as defunct (because the output\r
569 * thread is terminating by now).\r
570 */\r
571 h->u.o.sentdata(h, -h->u.o.writeerr);\r
572 h->u.o.defunct = TRUE;\r
573 } else {\r
574 bufchain_consume(&h->u.o.queued_data, h->u.o.lenwritten);\r
575 h->u.o.sentdata(h, bufchain_size(&h->u.o.queued_data));\r
576 handle_try_output(&h->u.o);\r
577 }\r
578 }\r
579 }\r
580 \r
581 void handle_unthrottle(struct handle *h, int backlog)\r
582 {\r
583 assert(!h->output);\r
584 handle_throttle(&h->u.i, backlog);\r
585 }\r
586 \r
587 int handle_backlog(struct handle *h)\r
588 {\r
589 assert(h->output);\r
590 return bufchain_size(&h->u.o.queued_data);\r
591 }\r
592 \r
593 void *handle_get_privdata(struct handle *h)\r
594 {\r
595 return h->u.g.privdata;\r
596 }\r