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bd99dc85 | 1 | /* Event loop machinery for the remote server for GDB. |
32d0add0 | 2 | Copyright (C) 1999-2015 Free Software Foundation, Inc. |
bd99dc85 PA |
3 | |
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
19 | /* Based on src/gdb/event-loop.c. */ | |
20 | ||
21 | #include "server.h" | |
60f662b0 | 22 | #include "queue.h" |
bd99dc85 PA |
23 | |
24 | #include <sys/types.h> | |
bd99dc85 PA |
25 | #include <sys/time.h> |
26 | ||
27 | #ifdef USE_WIN32API | |
28 | #include <windows.h> | |
29 | #include <io.h> | |
30 | #endif | |
31 | ||
e9464885 | 32 | #include <unistd.h> |
e9464885 | 33 | |
bd99dc85 | 34 | typedef struct gdb_event gdb_event; |
ec48365d | 35 | typedef int (event_handler_func) (gdb_fildes_t); |
bd99dc85 PA |
36 | |
37 | /* Tell create_file_handler what events we are interested in. */ | |
38 | ||
39 | #define GDB_READABLE (1<<1) | |
40 | #define GDB_WRITABLE (1<<2) | |
41 | #define GDB_EXCEPTION (1<<3) | |
42 | ||
60f662b0 YQ |
43 | /* Events are queued by calling 'QUEUE_enque (gdb_event_p, event_queue, |
44 | file_event_ptr)' and serviced later | |
bd99dc85 PA |
45 | on by do_one_event. An event can be, for instance, a file |
46 | descriptor becoming ready to be read. Servicing an event simply | |
47 | means that the procedure PROC will be called. We have 2 queues, | |
48 | one for file handlers that we listen to in the event loop, and one | |
49 | for the file handlers+events that are ready. The procedure PROC | |
50 | associated with each event is always the same (handle_file_event). | |
51 | Its duty is to invoke the handler associated with the file | |
52 | descriptor whose state change generated the event, plus doing other | |
53 | cleanups and such. */ | |
54 | ||
60f662b0 | 55 | typedef struct gdb_event |
bd99dc85 PA |
56 | { |
57 | /* Procedure to call to service this event. */ | |
58 | event_handler_func *proc; | |
59 | ||
60 | /* File descriptor that is ready. */ | |
ec48365d | 61 | gdb_fildes_t fd; |
60f662b0 | 62 | } *gdb_event_p; |
bd99dc85 PA |
63 | |
64 | /* Information about each file descriptor we register with the event | |
65 | loop. */ | |
66 | ||
67 | typedef struct file_handler | |
68 | { | |
69 | /* File descriptor. */ | |
ec48365d | 70 | gdb_fildes_t fd; |
bd99dc85 PA |
71 | |
72 | /* Events we want to monitor. */ | |
73 | int mask; | |
74 | ||
75 | /* Events that have been seen since the last time. */ | |
76 | int ready_mask; | |
77 | ||
78 | /* Procedure to call when fd is ready. */ | |
79 | handler_func *proc; | |
80 | ||
81 | /* Argument to pass to proc. */ | |
82 | gdb_client_data client_data; | |
83 | ||
84 | /* Was an error detected on this fd? */ | |
85 | int error; | |
86 | ||
87 | /* Next registered file descriptor. */ | |
88 | struct file_handler *next_file; | |
89 | } | |
90 | file_handler; | |
91 | ||
60f662b0 YQ |
92 | DECLARE_QUEUE_P(gdb_event_p); |
93 | static QUEUE(gdb_event_p) *event_queue = NULL; | |
94 | DEFINE_QUEUE_P(gdb_event_p); | |
bd99dc85 PA |
95 | |
96 | /* Gdb_notifier is just a list of file descriptors gdb is interested | |
97 | in. These are the input file descriptor, and the target file | |
98 | descriptor. Each of the elements in the gdb_notifier list is | |
99 | basically a description of what kind of events gdb is interested | |
100 | in, for each fd. */ | |
101 | ||
102 | static struct | |
103 | { | |
104 | /* Ptr to head of file handler list. */ | |
105 | file_handler *first_file_handler; | |
106 | ||
107 | /* Masks to be used in the next call to select. Bits are set in | |
108 | response to calls to create_file_handler. */ | |
109 | fd_set check_masks[3]; | |
110 | ||
111 | /* What file descriptors were found ready by select. */ | |
112 | fd_set ready_masks[3]; | |
113 | ||
114 | /* Number of valid bits (highest fd value + 1). (for select) */ | |
115 | int num_fds; | |
116 | } | |
117 | gdb_notifier; | |
118 | ||
24b066ba DE |
119 | /* Callbacks are just routines that are executed before waiting for the |
120 | next event. In GDB this is struct gdb_timer. We don't need timers | |
121 | so rather than copy all that complexity in gdbserver, we provide what | |
122 | we need, but we do so in a way that if/when the day comes that we need | |
123 | that complexity, it'll be easier to add - replace callbacks with timers | |
124 | and use a delta of zero (which is all gdb currently uses timers for anyway). | |
125 | ||
126 | PROC will be executed before gdbserver goes to sleep to wait for the | |
127 | next event. */ | |
128 | ||
129 | struct callback_event | |
130 | { | |
131 | int id; | |
132 | callback_handler_func *proc; | |
58c1b36c | 133 | gdb_client_data data; |
24b066ba DE |
134 | struct callback_event *next; |
135 | }; | |
136 | ||
137 | /* Table of registered callbacks. */ | |
138 | ||
139 | static struct | |
140 | { | |
141 | struct callback_event *first; | |
142 | struct callback_event *last; | |
143 | ||
144 | /* Id of the last callback created. */ | |
145 | int num_callbacks; | |
146 | } | |
147 | callback_list; | |
148 | ||
60f662b0 | 149 | /* Free EVENT. */ |
bd99dc85 PA |
150 | |
151 | static void | |
60f662b0 | 152 | gdb_event_xfree (struct gdb_event *event) |
bd99dc85 | 153 | { |
60f662b0 YQ |
154 | xfree (event); |
155 | } | |
bd99dc85 | 156 | |
60f662b0 YQ |
157 | void |
158 | initialize_event_loop (void) | |
159 | { | |
160 | event_queue = QUEUE_alloc (gdb_event_p, gdb_event_xfree); | |
bd99dc85 PA |
161 | } |
162 | ||
163 | /* Process one event. If an event was processed, 1 is returned | |
164 | otherwise 0 is returned. Scan the queue from head to tail, | |
165 | processing therefore the high priority events first, by invoking | |
166 | the associated event handler procedure. */ | |
167 | ||
168 | static int | |
169 | process_event (void) | |
170 | { | |
60f662b0 YQ |
171 | /* Let's get rid of the event from the event queue. We need to |
172 | do this now because while processing the event, since the | |
173 | proc function could end up jumping out to the caller of this | |
174 | function. In that case, we would have on the event queue an | |
175 | event which has been processed, but not deleted. */ | |
176 | if (!QUEUE_is_empty (gdb_event_p, event_queue)) | |
bd99dc85 | 177 | { |
60f662b0 YQ |
178 | gdb_event *event_ptr = QUEUE_deque (gdb_event_p, event_queue); |
179 | event_handler_func *proc = event_ptr->proc; | |
180 | gdb_fildes_t fd = event_ptr->fd; | |
bd99dc85 | 181 | |
60f662b0 | 182 | gdb_event_xfree (event_ptr); |
bd99dc85 | 183 | /* Now call the procedure associated with the event. */ |
8336d594 PA |
184 | if ((*proc) (fd)) |
185 | return -1; | |
bd99dc85 PA |
186 | return 1; |
187 | } | |
188 | ||
189 | /* This is the case if there are no event on the event queue. */ | |
190 | return 0; | |
191 | } | |
192 | ||
24b066ba DE |
193 | /* Append PROC to the callback list. |
194 | The result is the "id" of the callback that can be passed back to | |
195 | delete_callback_event. */ | |
196 | ||
197 | int | |
198 | append_callback_event (callback_handler_func *proc, gdb_client_data data) | |
199 | { | |
200 | struct callback_event *event_ptr; | |
201 | ||
202 | event_ptr = xmalloc (sizeof (*event_ptr)); | |
203 | event_ptr->id = callback_list.num_callbacks++; | |
204 | event_ptr->proc = proc; | |
205 | event_ptr->data = data; | |
206 | event_ptr->next = NULL; | |
207 | if (callback_list.first == NULL) | |
208 | callback_list.first = event_ptr; | |
209 | if (callback_list.last != NULL) | |
210 | callback_list.last->next = event_ptr; | |
211 | callback_list.last = event_ptr; | |
212 | return event_ptr->id; | |
213 | } | |
214 | ||
215 | /* Delete callback ID. | |
216 | It is not an error callback ID doesn't exist. */ | |
217 | ||
218 | void | |
219 | delete_callback_event (int id) | |
220 | { | |
221 | struct callback_event **p; | |
222 | ||
223 | for (p = &callback_list.first; *p != NULL; p = &(*p)->next) | |
224 | { | |
225 | struct callback_event *event_ptr = *p; | |
226 | ||
227 | if (event_ptr->id == id) | |
228 | { | |
229 | *p = event_ptr->next; | |
230 | if (event_ptr == callback_list.last) | |
231 | callback_list.last = NULL; | |
232 | free (event_ptr); | |
233 | break; | |
234 | } | |
235 | } | |
236 | } | |
237 | ||
238 | /* Run the next callback. | |
239 | The result is 1 if a callback was called and event processing | |
240 | should continue, -1 if the callback wants the event loop to exit, | |
241 | and 0 if there are no more callbacks. */ | |
242 | ||
243 | static int | |
244 | process_callback (void) | |
245 | { | |
246 | struct callback_event *event_ptr; | |
247 | ||
248 | event_ptr = callback_list.first; | |
249 | if (event_ptr != NULL) | |
250 | { | |
251 | callback_handler_func *proc = event_ptr->proc; | |
58c1b36c | 252 | gdb_client_data data = event_ptr->data; |
24b066ba DE |
253 | |
254 | /* Remove the event before calling PROC, | |
255 | more events may get added by PROC. */ | |
256 | callback_list.first = event_ptr->next; | |
257 | if (callback_list.first == NULL) | |
258 | callback_list.last = NULL; | |
259 | free (event_ptr); | |
260 | if ((*proc) (data)) | |
261 | return -1; | |
262 | return 1; | |
263 | } | |
264 | ||
265 | return 0; | |
266 | } | |
267 | ||
bd99dc85 PA |
268 | /* Add a file handler/descriptor to the list of descriptors we are |
269 | interested in. FD is the file descriptor for the file/stream to be | |
270 | listened to. MASK is a combination of READABLE, WRITABLE, | |
271 | EXCEPTION. PROC is the procedure that will be called when an event | |
272 | occurs for FD. CLIENT_DATA is the argument to pass to PROC. */ | |
273 | ||
274 | static void | |
ec48365d | 275 | create_file_handler (gdb_fildes_t fd, int mask, handler_func *proc, |
bd99dc85 PA |
276 | gdb_client_data client_data) |
277 | { | |
278 | file_handler *file_ptr; | |
279 | ||
280 | /* Do we already have a file handler for this file? (We may be | |
281 | changing its associated procedure). */ | |
282 | for (file_ptr = gdb_notifier.first_file_handler; | |
283 | file_ptr != NULL; | |
284 | file_ptr = file_ptr->next_file) | |
285 | if (file_ptr->fd == fd) | |
286 | break; | |
287 | ||
288 | /* It is a new file descriptor. Add it to the list. Otherwise, | |
289 | just change the data associated with it. */ | |
290 | if (file_ptr == NULL) | |
291 | { | |
292 | file_ptr = xmalloc (sizeof (*file_ptr)); | |
293 | file_ptr->fd = fd; | |
294 | file_ptr->ready_mask = 0; | |
295 | file_ptr->next_file = gdb_notifier.first_file_handler; | |
296 | gdb_notifier.first_file_handler = file_ptr; | |
297 | ||
298 | if (mask & GDB_READABLE) | |
299 | FD_SET (fd, &gdb_notifier.check_masks[0]); | |
300 | else | |
301 | FD_CLR (fd, &gdb_notifier.check_masks[0]); | |
302 | ||
303 | if (mask & GDB_WRITABLE) | |
304 | FD_SET (fd, &gdb_notifier.check_masks[1]); | |
305 | else | |
306 | FD_CLR (fd, &gdb_notifier.check_masks[1]); | |
307 | ||
308 | if (mask & GDB_EXCEPTION) | |
309 | FD_SET (fd, &gdb_notifier.check_masks[2]); | |
310 | else | |
311 | FD_CLR (fd, &gdb_notifier.check_masks[2]); | |
312 | ||
313 | if (gdb_notifier.num_fds <= fd) | |
314 | gdb_notifier.num_fds = fd + 1; | |
315 | } | |
316 | ||
317 | file_ptr->proc = proc; | |
318 | file_ptr->client_data = client_data; | |
319 | file_ptr->mask = mask; | |
320 | } | |
321 | ||
322 | /* Wrapper function for create_file_handler. */ | |
323 | ||
324 | void | |
ec48365d PA |
325 | add_file_handler (gdb_fildes_t fd, |
326 | handler_func *proc, gdb_client_data client_data) | |
bd99dc85 PA |
327 | { |
328 | create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION, proc, client_data); | |
329 | } | |
330 | ||
331 | /* Remove the file descriptor FD from the list of monitored fd's: | |
332 | i.e. we don't care anymore about events on the FD. */ | |
333 | ||
334 | void | |
ec48365d | 335 | delete_file_handler (gdb_fildes_t fd) |
bd99dc85 PA |
336 | { |
337 | file_handler *file_ptr, *prev_ptr = NULL; | |
338 | int i; | |
339 | ||
340 | /* Find the entry for the given file. */ | |
341 | ||
342 | for (file_ptr = gdb_notifier.first_file_handler; | |
343 | file_ptr != NULL; | |
344 | file_ptr = file_ptr->next_file) | |
345 | if (file_ptr->fd == fd) | |
346 | break; | |
347 | ||
348 | if (file_ptr == NULL) | |
349 | return; | |
350 | ||
351 | if (file_ptr->mask & GDB_READABLE) | |
352 | FD_CLR (fd, &gdb_notifier.check_masks[0]); | |
353 | if (file_ptr->mask & GDB_WRITABLE) | |
354 | FD_CLR (fd, &gdb_notifier.check_masks[1]); | |
355 | if (file_ptr->mask & GDB_EXCEPTION) | |
356 | FD_CLR (fd, &gdb_notifier.check_masks[2]); | |
357 | ||
358 | /* Find current max fd. */ | |
359 | ||
360 | if ((fd + 1) == gdb_notifier.num_fds) | |
361 | { | |
362 | gdb_notifier.num_fds--; | |
363 | for (i = gdb_notifier.num_fds; i; i--) | |
364 | { | |
365 | if (FD_ISSET (i - 1, &gdb_notifier.check_masks[0]) | |
366 | || FD_ISSET (i - 1, &gdb_notifier.check_masks[1]) | |
367 | || FD_ISSET (i - 1, &gdb_notifier.check_masks[2])) | |
368 | break; | |
369 | } | |
370 | gdb_notifier.num_fds = i; | |
371 | } | |
372 | ||
373 | /* Deactivate the file descriptor, by clearing its mask, so that it | |
374 | will not fire again. */ | |
375 | ||
376 | file_ptr->mask = 0; | |
377 | ||
378 | /* Get rid of the file handler in the file handler list. */ | |
379 | if (file_ptr == gdb_notifier.first_file_handler) | |
380 | gdb_notifier.first_file_handler = file_ptr->next_file; | |
381 | else | |
382 | { | |
383 | for (prev_ptr = gdb_notifier.first_file_handler; | |
384 | prev_ptr->next_file != file_ptr; | |
385 | prev_ptr = prev_ptr->next_file) | |
386 | ; | |
387 | prev_ptr->next_file = file_ptr->next_file; | |
388 | } | |
389 | free (file_ptr); | |
390 | } | |
391 | ||
392 | /* Handle the given event by calling the procedure associated to the | |
393 | corresponding file handler. Called by process_event indirectly, | |
394 | through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the | |
395 | event in the front of the event queue. */ | |
396 | ||
8336d594 | 397 | static int |
ec48365d | 398 | handle_file_event (gdb_fildes_t event_file_desc) |
bd99dc85 PA |
399 | { |
400 | file_handler *file_ptr; | |
401 | int mask; | |
402 | ||
403 | /* Search the file handler list to find one that matches the fd in | |
404 | the event. */ | |
405 | for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL; | |
406 | file_ptr = file_ptr->next_file) | |
407 | { | |
408 | if (file_ptr->fd == event_file_desc) | |
409 | { | |
410 | /* See if the desired events (mask) match the received | |
411 | events (ready_mask). */ | |
412 | ||
413 | if (file_ptr->ready_mask & GDB_EXCEPTION) | |
414 | { | |
ec48365d PA |
415 | fprintf (stderr, "Exception condition detected on fd %s\n", |
416 | pfildes (file_ptr->fd)); | |
bd99dc85 PA |
417 | file_ptr->error = 1; |
418 | } | |
419 | else | |
420 | file_ptr->error = 0; | |
421 | mask = file_ptr->ready_mask & file_ptr->mask; | |
422 | ||
423 | /* Clear the received events for next time around. */ | |
424 | file_ptr->ready_mask = 0; | |
425 | ||
426 | /* If there was a match, then call the handler. */ | |
427 | if (mask != 0) | |
8336d594 PA |
428 | { |
429 | if ((*file_ptr->proc) (file_ptr->error, | |
430 | file_ptr->client_data) < 0) | |
431 | return -1; | |
432 | } | |
bd99dc85 PA |
433 | break; |
434 | } | |
435 | } | |
8336d594 PA |
436 | |
437 | return 0; | |
bd99dc85 PA |
438 | } |
439 | ||
440 | /* Create a file event, to be enqueued in the event queue for | |
441 | processing. The procedure associated to this event is always | |
442 | handle_file_event, which will in turn invoke the one that was | |
443 | associated to FD when it was registered with the event loop. */ | |
444 | ||
445 | static gdb_event * | |
ec48365d | 446 | create_file_event (gdb_fildes_t fd) |
bd99dc85 PA |
447 | { |
448 | gdb_event *file_event_ptr; | |
449 | ||
450 | file_event_ptr = xmalloc (sizeof (gdb_event)); | |
451 | file_event_ptr->proc = handle_file_event; | |
452 | file_event_ptr->fd = fd; | |
453 | return file_event_ptr; | |
454 | } | |
455 | ||
456 | /* Called by do_one_event to wait for new events on the monitored file | |
457 | descriptors. Queue file events as they are detected by the poll. | |
458 | If there are no events, this function will block in the call to | |
459 | select. Return -1 if there are no files descriptors to monitor, | |
460 | otherwise return 0. */ | |
461 | ||
462 | static int | |
463 | wait_for_event (void) | |
464 | { | |
465 | file_handler *file_ptr; | |
bd99dc85 PA |
466 | int num_found = 0; |
467 | ||
468 | /* Make sure all output is done before getting another event. */ | |
469 | fflush (stdout); | |
470 | fflush (stderr); | |
471 | ||
472 | if (gdb_notifier.num_fds == 0) | |
473 | return -1; | |
474 | ||
475 | gdb_notifier.ready_masks[0] = gdb_notifier.check_masks[0]; | |
476 | gdb_notifier.ready_masks[1] = gdb_notifier.check_masks[1]; | |
477 | gdb_notifier.ready_masks[2] = gdb_notifier.check_masks[2]; | |
478 | num_found = select (gdb_notifier.num_fds, | |
479 | &gdb_notifier.ready_masks[0], | |
480 | &gdb_notifier.ready_masks[1], | |
481 | &gdb_notifier.ready_masks[2], | |
482 | NULL); | |
483 | ||
484 | /* Clear the masks after an error from select. */ | |
485 | if (num_found == -1) | |
486 | { | |
487 | FD_ZERO (&gdb_notifier.ready_masks[0]); | |
488 | FD_ZERO (&gdb_notifier.ready_masks[1]); | |
489 | FD_ZERO (&gdb_notifier.ready_masks[2]); | |
490 | #ifdef EINTR | |
491 | /* Dont print anything if we got a signal, let gdb handle | |
492 | it. */ | |
493 | if (errno != EINTR) | |
494 | perror_with_name ("select"); | |
495 | #endif | |
496 | } | |
497 | ||
498 | /* Enqueue all detected file events. */ | |
499 | ||
500 | for (file_ptr = gdb_notifier.first_file_handler; | |
501 | file_ptr != NULL && num_found > 0; | |
502 | file_ptr = file_ptr->next_file) | |
503 | { | |
504 | int mask = 0; | |
505 | ||
506 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[0])) | |
507 | mask |= GDB_READABLE; | |
508 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[1])) | |
509 | mask |= GDB_WRITABLE; | |
510 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[2])) | |
511 | mask |= GDB_EXCEPTION; | |
512 | ||
513 | if (!mask) | |
514 | continue; | |
515 | else | |
516 | num_found--; | |
517 | ||
518 | /* Enqueue an event only if this is still a new event for this | |
519 | fd. */ | |
520 | ||
521 | if (file_ptr->ready_mask == 0) | |
522 | { | |
60f662b0 YQ |
523 | gdb_event *file_event_ptr = create_file_event (file_ptr->fd); |
524 | ||
525 | QUEUE_enque (gdb_event_p, event_queue, file_event_ptr); | |
bd99dc85 PA |
526 | } |
527 | file_ptr->ready_mask = mask; | |
528 | } | |
529 | ||
530 | return 0; | |
531 | } | |
532 | ||
533 | /* Start up the event loop. This is the entry point to the event | |
534 | loop. */ | |
535 | ||
536 | void | |
537 | start_event_loop (void) | |
538 | { | |
539 | /* Loop until there is nothing to do. This is the entry point to | |
540 | the event loop engine. If nothing is ready at this time, wait | |
541 | for something to happen (via wait_for_event), then process it. | |
542 | Return when there are no longer event sources to wait for. */ | |
543 | ||
544 | while (1) | |
545 | { | |
546 | /* Any events already waiting in the queue? */ | |
8336d594 PA |
547 | int res = process_event (); |
548 | ||
549 | /* Did the event handler want the event loop to stop? */ | |
550 | if (res == -1) | |
551 | return; | |
552 | ||
553 | if (res) | |
bd99dc85 PA |
554 | continue; |
555 | ||
24b066ba DE |
556 | /* Process any queued callbacks before we go to sleep. */ |
557 | res = process_callback (); | |
558 | ||
559 | /* Did the callback want the event loop to stop? */ | |
560 | if (res == -1) | |
561 | return; | |
562 | ||
563 | if (res) | |
564 | continue; | |
565 | ||
bd99dc85 PA |
566 | /* Wait for a new event. If wait_for_event returns -1, we |
567 | should get out because this means that there are no event | |
568 | sources left. This will make the event loop stop, and the | |
569 | application exit. */ | |
570 | ||
571 | if (wait_for_event () < 0) | |
572 | return; | |
573 | } | |
574 | ||
575 | /* We are done with the event loop. There are no more event sources | |
576 | to listen to. So we exit gdbserver. */ | |
577 | } |