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bd99dc85 | 1 | /* Event loop machinery for the remote server for GDB. |
ecd75fc8 | 2 | Copyright (C) 1999-2014 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> | |
25 | #include <string.h> | |
26 | #include <sys/time.h> | |
27 | ||
28 | #ifdef USE_WIN32API | |
29 | #include <windows.h> | |
30 | #include <io.h> | |
31 | #endif | |
32 | ||
33 | #ifdef HAVE_ERRNO_H | |
34 | #include <errno.h> | |
35 | #endif | |
36 | ||
e9464885 | 37 | #include <unistd.h> |
e9464885 | 38 | |
bd99dc85 | 39 | typedef struct gdb_event gdb_event; |
ec48365d | 40 | typedef int (event_handler_func) (gdb_fildes_t); |
bd99dc85 PA |
41 | |
42 | /* Tell create_file_handler what events we are interested in. */ | |
43 | ||
44 | #define GDB_READABLE (1<<1) | |
45 | #define GDB_WRITABLE (1<<2) | |
46 | #define GDB_EXCEPTION (1<<3) | |
47 | ||
60f662b0 YQ |
48 | /* Events are queued by calling 'QUEUE_enque (gdb_event_p, event_queue, |
49 | file_event_ptr)' and serviced later | |
bd99dc85 PA |
50 | on by do_one_event. An event can be, for instance, a file |
51 | descriptor becoming ready to be read. Servicing an event simply | |
52 | means that the procedure PROC will be called. We have 2 queues, | |
53 | one for file handlers that we listen to in the event loop, and one | |
54 | for the file handlers+events that are ready. The procedure PROC | |
55 | associated with each event is always the same (handle_file_event). | |
56 | Its duty is to invoke the handler associated with the file | |
57 | descriptor whose state change generated the event, plus doing other | |
58 | cleanups and such. */ | |
59 | ||
60f662b0 | 60 | typedef struct gdb_event |
bd99dc85 PA |
61 | { |
62 | /* Procedure to call to service this event. */ | |
63 | event_handler_func *proc; | |
64 | ||
65 | /* File descriptor that is ready. */ | |
ec48365d | 66 | gdb_fildes_t fd; |
60f662b0 | 67 | } *gdb_event_p; |
bd99dc85 PA |
68 | |
69 | /* Information about each file descriptor we register with the event | |
70 | loop. */ | |
71 | ||
72 | typedef struct file_handler | |
73 | { | |
74 | /* File descriptor. */ | |
ec48365d | 75 | gdb_fildes_t fd; |
bd99dc85 PA |
76 | |
77 | /* Events we want to monitor. */ | |
78 | int mask; | |
79 | ||
80 | /* Events that have been seen since the last time. */ | |
81 | int ready_mask; | |
82 | ||
83 | /* Procedure to call when fd is ready. */ | |
84 | handler_func *proc; | |
85 | ||
86 | /* Argument to pass to proc. */ | |
87 | gdb_client_data client_data; | |
88 | ||
89 | /* Was an error detected on this fd? */ | |
90 | int error; | |
91 | ||
92 | /* Next registered file descriptor. */ | |
93 | struct file_handler *next_file; | |
94 | } | |
95 | file_handler; | |
96 | ||
60f662b0 YQ |
97 | DECLARE_QUEUE_P(gdb_event_p); |
98 | static QUEUE(gdb_event_p) *event_queue = NULL; | |
99 | DEFINE_QUEUE_P(gdb_event_p); | |
bd99dc85 PA |
100 | |
101 | /* Gdb_notifier is just a list of file descriptors gdb is interested | |
102 | in. These are the input file descriptor, and the target file | |
103 | descriptor. Each of the elements in the gdb_notifier list is | |
104 | basically a description of what kind of events gdb is interested | |
105 | in, for each fd. */ | |
106 | ||
107 | static struct | |
108 | { | |
109 | /* Ptr to head of file handler list. */ | |
110 | file_handler *first_file_handler; | |
111 | ||
112 | /* Masks to be used in the next call to select. Bits are set in | |
113 | response to calls to create_file_handler. */ | |
114 | fd_set check_masks[3]; | |
115 | ||
116 | /* What file descriptors were found ready by select. */ | |
117 | fd_set ready_masks[3]; | |
118 | ||
119 | /* Number of valid bits (highest fd value + 1). (for select) */ | |
120 | int num_fds; | |
121 | } | |
122 | gdb_notifier; | |
123 | ||
24b066ba DE |
124 | /* Callbacks are just routines that are executed before waiting for the |
125 | next event. In GDB this is struct gdb_timer. We don't need timers | |
126 | so rather than copy all that complexity in gdbserver, we provide what | |
127 | we need, but we do so in a way that if/when the day comes that we need | |
128 | that complexity, it'll be easier to add - replace callbacks with timers | |
129 | and use a delta of zero (which is all gdb currently uses timers for anyway). | |
130 | ||
131 | PROC will be executed before gdbserver goes to sleep to wait for the | |
132 | next event. */ | |
133 | ||
134 | struct callback_event | |
135 | { | |
136 | int id; | |
137 | callback_handler_func *proc; | |
138 | gdb_client_data *data; | |
139 | struct callback_event *next; | |
140 | }; | |
141 | ||
142 | /* Table of registered callbacks. */ | |
143 | ||
144 | static struct | |
145 | { | |
146 | struct callback_event *first; | |
147 | struct callback_event *last; | |
148 | ||
149 | /* Id of the last callback created. */ | |
150 | int num_callbacks; | |
151 | } | |
152 | callback_list; | |
153 | ||
60f662b0 | 154 | /* Free EVENT. */ |
bd99dc85 PA |
155 | |
156 | static void | |
60f662b0 | 157 | gdb_event_xfree (struct gdb_event *event) |
bd99dc85 | 158 | { |
60f662b0 YQ |
159 | xfree (event); |
160 | } | |
bd99dc85 | 161 | |
60f662b0 YQ |
162 | void |
163 | initialize_event_loop (void) | |
164 | { | |
165 | event_queue = QUEUE_alloc (gdb_event_p, gdb_event_xfree); | |
bd99dc85 PA |
166 | } |
167 | ||
168 | /* Process one event. If an event was processed, 1 is returned | |
169 | otherwise 0 is returned. Scan the queue from head to tail, | |
170 | processing therefore the high priority events first, by invoking | |
171 | the associated event handler procedure. */ | |
172 | ||
173 | static int | |
174 | process_event (void) | |
175 | { | |
60f662b0 YQ |
176 | /* Let's get rid of the event from the event queue. We need to |
177 | do this now because while processing the event, since the | |
178 | proc function could end up jumping out to the caller of this | |
179 | function. In that case, we would have on the event queue an | |
180 | event which has been processed, but not deleted. */ | |
181 | if (!QUEUE_is_empty (gdb_event_p, event_queue)) | |
bd99dc85 | 182 | { |
60f662b0 YQ |
183 | gdb_event *event_ptr = QUEUE_deque (gdb_event_p, event_queue); |
184 | event_handler_func *proc = event_ptr->proc; | |
185 | gdb_fildes_t fd = event_ptr->fd; | |
bd99dc85 | 186 | |
60f662b0 | 187 | gdb_event_xfree (event_ptr); |
bd99dc85 | 188 | /* Now call the procedure associated with the event. */ |
8336d594 PA |
189 | if ((*proc) (fd)) |
190 | return -1; | |
bd99dc85 PA |
191 | return 1; |
192 | } | |
193 | ||
194 | /* This is the case if there are no event on the event queue. */ | |
195 | return 0; | |
196 | } | |
197 | ||
24b066ba DE |
198 | /* Append PROC to the callback list. |
199 | The result is the "id" of the callback that can be passed back to | |
200 | delete_callback_event. */ | |
201 | ||
202 | int | |
203 | append_callback_event (callback_handler_func *proc, gdb_client_data data) | |
204 | { | |
205 | struct callback_event *event_ptr; | |
206 | ||
207 | event_ptr = xmalloc (sizeof (*event_ptr)); | |
208 | event_ptr->id = callback_list.num_callbacks++; | |
209 | event_ptr->proc = proc; | |
210 | event_ptr->data = data; | |
211 | event_ptr->next = NULL; | |
212 | if (callback_list.first == NULL) | |
213 | callback_list.first = event_ptr; | |
214 | if (callback_list.last != NULL) | |
215 | callback_list.last->next = event_ptr; | |
216 | callback_list.last = event_ptr; | |
217 | return event_ptr->id; | |
218 | } | |
219 | ||
220 | /* Delete callback ID. | |
221 | It is not an error callback ID doesn't exist. */ | |
222 | ||
223 | void | |
224 | delete_callback_event (int id) | |
225 | { | |
226 | struct callback_event **p; | |
227 | ||
228 | for (p = &callback_list.first; *p != NULL; p = &(*p)->next) | |
229 | { | |
230 | struct callback_event *event_ptr = *p; | |
231 | ||
232 | if (event_ptr->id == id) | |
233 | { | |
234 | *p = event_ptr->next; | |
235 | if (event_ptr == callback_list.last) | |
236 | callback_list.last = NULL; | |
237 | free (event_ptr); | |
238 | break; | |
239 | } | |
240 | } | |
241 | } | |
242 | ||
243 | /* Run the next callback. | |
244 | The result is 1 if a callback was called and event processing | |
245 | should continue, -1 if the callback wants the event loop to exit, | |
246 | and 0 if there are no more callbacks. */ | |
247 | ||
248 | static int | |
249 | process_callback (void) | |
250 | { | |
251 | struct callback_event *event_ptr; | |
252 | ||
253 | event_ptr = callback_list.first; | |
254 | if (event_ptr != NULL) | |
255 | { | |
256 | callback_handler_func *proc = event_ptr->proc; | |
257 | gdb_client_data *data = event_ptr->data; | |
258 | ||
259 | /* Remove the event before calling PROC, | |
260 | more events may get added by PROC. */ | |
261 | callback_list.first = event_ptr->next; | |
262 | if (callback_list.first == NULL) | |
263 | callback_list.last = NULL; | |
264 | free (event_ptr); | |
265 | if ((*proc) (data)) | |
266 | return -1; | |
267 | return 1; | |
268 | } | |
269 | ||
270 | return 0; | |
271 | } | |
272 | ||
bd99dc85 PA |
273 | /* Add a file handler/descriptor to the list of descriptors we are |
274 | interested in. FD is the file descriptor for the file/stream to be | |
275 | listened to. MASK is a combination of READABLE, WRITABLE, | |
276 | EXCEPTION. PROC is the procedure that will be called when an event | |
277 | occurs for FD. CLIENT_DATA is the argument to pass to PROC. */ | |
278 | ||
279 | static void | |
ec48365d | 280 | create_file_handler (gdb_fildes_t fd, int mask, handler_func *proc, |
bd99dc85 PA |
281 | gdb_client_data client_data) |
282 | { | |
283 | file_handler *file_ptr; | |
284 | ||
285 | /* Do we already have a file handler for this file? (We may be | |
286 | changing its associated procedure). */ | |
287 | for (file_ptr = gdb_notifier.first_file_handler; | |
288 | file_ptr != NULL; | |
289 | file_ptr = file_ptr->next_file) | |
290 | if (file_ptr->fd == fd) | |
291 | break; | |
292 | ||
293 | /* It is a new file descriptor. Add it to the list. Otherwise, | |
294 | just change the data associated with it. */ | |
295 | if (file_ptr == NULL) | |
296 | { | |
297 | file_ptr = xmalloc (sizeof (*file_ptr)); | |
298 | file_ptr->fd = fd; | |
299 | file_ptr->ready_mask = 0; | |
300 | file_ptr->next_file = gdb_notifier.first_file_handler; | |
301 | gdb_notifier.first_file_handler = file_ptr; | |
302 | ||
303 | if (mask & GDB_READABLE) | |
304 | FD_SET (fd, &gdb_notifier.check_masks[0]); | |
305 | else | |
306 | FD_CLR (fd, &gdb_notifier.check_masks[0]); | |
307 | ||
308 | if (mask & GDB_WRITABLE) | |
309 | FD_SET (fd, &gdb_notifier.check_masks[1]); | |
310 | else | |
311 | FD_CLR (fd, &gdb_notifier.check_masks[1]); | |
312 | ||
313 | if (mask & GDB_EXCEPTION) | |
314 | FD_SET (fd, &gdb_notifier.check_masks[2]); | |
315 | else | |
316 | FD_CLR (fd, &gdb_notifier.check_masks[2]); | |
317 | ||
318 | if (gdb_notifier.num_fds <= fd) | |
319 | gdb_notifier.num_fds = fd + 1; | |
320 | } | |
321 | ||
322 | file_ptr->proc = proc; | |
323 | file_ptr->client_data = client_data; | |
324 | file_ptr->mask = mask; | |
325 | } | |
326 | ||
327 | /* Wrapper function for create_file_handler. */ | |
328 | ||
329 | void | |
ec48365d PA |
330 | add_file_handler (gdb_fildes_t fd, |
331 | handler_func *proc, gdb_client_data client_data) | |
bd99dc85 PA |
332 | { |
333 | create_file_handler (fd, GDB_READABLE | GDB_EXCEPTION, proc, client_data); | |
334 | } | |
335 | ||
336 | /* Remove the file descriptor FD from the list of monitored fd's: | |
337 | i.e. we don't care anymore about events on the FD. */ | |
338 | ||
339 | void | |
ec48365d | 340 | delete_file_handler (gdb_fildes_t fd) |
bd99dc85 PA |
341 | { |
342 | file_handler *file_ptr, *prev_ptr = NULL; | |
343 | int i; | |
344 | ||
345 | /* Find the entry for the given file. */ | |
346 | ||
347 | for (file_ptr = gdb_notifier.first_file_handler; | |
348 | file_ptr != NULL; | |
349 | file_ptr = file_ptr->next_file) | |
350 | if (file_ptr->fd == fd) | |
351 | break; | |
352 | ||
353 | if (file_ptr == NULL) | |
354 | return; | |
355 | ||
356 | if (file_ptr->mask & GDB_READABLE) | |
357 | FD_CLR (fd, &gdb_notifier.check_masks[0]); | |
358 | if (file_ptr->mask & GDB_WRITABLE) | |
359 | FD_CLR (fd, &gdb_notifier.check_masks[1]); | |
360 | if (file_ptr->mask & GDB_EXCEPTION) | |
361 | FD_CLR (fd, &gdb_notifier.check_masks[2]); | |
362 | ||
363 | /* Find current max fd. */ | |
364 | ||
365 | if ((fd + 1) == gdb_notifier.num_fds) | |
366 | { | |
367 | gdb_notifier.num_fds--; | |
368 | for (i = gdb_notifier.num_fds; i; i--) | |
369 | { | |
370 | if (FD_ISSET (i - 1, &gdb_notifier.check_masks[0]) | |
371 | || FD_ISSET (i - 1, &gdb_notifier.check_masks[1]) | |
372 | || FD_ISSET (i - 1, &gdb_notifier.check_masks[2])) | |
373 | break; | |
374 | } | |
375 | gdb_notifier.num_fds = i; | |
376 | } | |
377 | ||
378 | /* Deactivate the file descriptor, by clearing its mask, so that it | |
379 | will not fire again. */ | |
380 | ||
381 | file_ptr->mask = 0; | |
382 | ||
383 | /* Get rid of the file handler in the file handler list. */ | |
384 | if (file_ptr == gdb_notifier.first_file_handler) | |
385 | gdb_notifier.first_file_handler = file_ptr->next_file; | |
386 | else | |
387 | { | |
388 | for (prev_ptr = gdb_notifier.first_file_handler; | |
389 | prev_ptr->next_file != file_ptr; | |
390 | prev_ptr = prev_ptr->next_file) | |
391 | ; | |
392 | prev_ptr->next_file = file_ptr->next_file; | |
393 | } | |
394 | free (file_ptr); | |
395 | } | |
396 | ||
397 | /* Handle the given event by calling the procedure associated to the | |
398 | corresponding file handler. Called by process_event indirectly, | |
399 | through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the | |
400 | event in the front of the event queue. */ | |
401 | ||
8336d594 | 402 | static int |
ec48365d | 403 | handle_file_event (gdb_fildes_t event_file_desc) |
bd99dc85 PA |
404 | { |
405 | file_handler *file_ptr; | |
406 | int mask; | |
407 | ||
408 | /* Search the file handler list to find one that matches the fd in | |
409 | the event. */ | |
410 | for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL; | |
411 | file_ptr = file_ptr->next_file) | |
412 | { | |
413 | if (file_ptr->fd == event_file_desc) | |
414 | { | |
415 | /* See if the desired events (mask) match the received | |
416 | events (ready_mask). */ | |
417 | ||
418 | if (file_ptr->ready_mask & GDB_EXCEPTION) | |
419 | { | |
ec48365d PA |
420 | fprintf (stderr, "Exception condition detected on fd %s\n", |
421 | pfildes (file_ptr->fd)); | |
bd99dc85 PA |
422 | file_ptr->error = 1; |
423 | } | |
424 | else | |
425 | file_ptr->error = 0; | |
426 | mask = file_ptr->ready_mask & file_ptr->mask; | |
427 | ||
428 | /* Clear the received events for next time around. */ | |
429 | file_ptr->ready_mask = 0; | |
430 | ||
431 | /* If there was a match, then call the handler. */ | |
432 | if (mask != 0) | |
8336d594 PA |
433 | { |
434 | if ((*file_ptr->proc) (file_ptr->error, | |
435 | file_ptr->client_data) < 0) | |
436 | return -1; | |
437 | } | |
bd99dc85 PA |
438 | break; |
439 | } | |
440 | } | |
8336d594 PA |
441 | |
442 | return 0; | |
bd99dc85 PA |
443 | } |
444 | ||
445 | /* Create a file event, to be enqueued in the event queue for | |
446 | processing. The procedure associated to this event is always | |
447 | handle_file_event, which will in turn invoke the one that was | |
448 | associated to FD when it was registered with the event loop. */ | |
449 | ||
450 | static gdb_event * | |
ec48365d | 451 | create_file_event (gdb_fildes_t fd) |
bd99dc85 PA |
452 | { |
453 | gdb_event *file_event_ptr; | |
454 | ||
455 | file_event_ptr = xmalloc (sizeof (gdb_event)); | |
456 | file_event_ptr->proc = handle_file_event; | |
457 | file_event_ptr->fd = fd; | |
458 | return file_event_ptr; | |
459 | } | |
460 | ||
461 | /* Called by do_one_event to wait for new events on the monitored file | |
462 | descriptors. Queue file events as they are detected by the poll. | |
463 | If there are no events, this function will block in the call to | |
464 | select. Return -1 if there are no files descriptors to monitor, | |
465 | otherwise return 0. */ | |
466 | ||
467 | static int | |
468 | wait_for_event (void) | |
469 | { | |
470 | file_handler *file_ptr; | |
bd99dc85 PA |
471 | int num_found = 0; |
472 | ||
473 | /* Make sure all output is done before getting another event. */ | |
474 | fflush (stdout); | |
475 | fflush (stderr); | |
476 | ||
477 | if (gdb_notifier.num_fds == 0) | |
478 | return -1; | |
479 | ||
480 | gdb_notifier.ready_masks[0] = gdb_notifier.check_masks[0]; | |
481 | gdb_notifier.ready_masks[1] = gdb_notifier.check_masks[1]; | |
482 | gdb_notifier.ready_masks[2] = gdb_notifier.check_masks[2]; | |
483 | num_found = select (gdb_notifier.num_fds, | |
484 | &gdb_notifier.ready_masks[0], | |
485 | &gdb_notifier.ready_masks[1], | |
486 | &gdb_notifier.ready_masks[2], | |
487 | NULL); | |
488 | ||
489 | /* Clear the masks after an error from select. */ | |
490 | if (num_found == -1) | |
491 | { | |
492 | FD_ZERO (&gdb_notifier.ready_masks[0]); | |
493 | FD_ZERO (&gdb_notifier.ready_masks[1]); | |
494 | FD_ZERO (&gdb_notifier.ready_masks[2]); | |
495 | #ifdef EINTR | |
496 | /* Dont print anything if we got a signal, let gdb handle | |
497 | it. */ | |
498 | if (errno != EINTR) | |
499 | perror_with_name ("select"); | |
500 | #endif | |
501 | } | |
502 | ||
503 | /* Enqueue all detected file events. */ | |
504 | ||
505 | for (file_ptr = gdb_notifier.first_file_handler; | |
506 | file_ptr != NULL && num_found > 0; | |
507 | file_ptr = file_ptr->next_file) | |
508 | { | |
509 | int mask = 0; | |
510 | ||
511 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[0])) | |
512 | mask |= GDB_READABLE; | |
513 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[1])) | |
514 | mask |= GDB_WRITABLE; | |
515 | if (FD_ISSET (file_ptr->fd, &gdb_notifier.ready_masks[2])) | |
516 | mask |= GDB_EXCEPTION; | |
517 | ||
518 | if (!mask) | |
519 | continue; | |
520 | else | |
521 | num_found--; | |
522 | ||
523 | /* Enqueue an event only if this is still a new event for this | |
524 | fd. */ | |
525 | ||
526 | if (file_ptr->ready_mask == 0) | |
527 | { | |
60f662b0 YQ |
528 | gdb_event *file_event_ptr = create_file_event (file_ptr->fd); |
529 | ||
530 | QUEUE_enque (gdb_event_p, event_queue, file_event_ptr); | |
bd99dc85 PA |
531 | } |
532 | file_ptr->ready_mask = mask; | |
533 | } | |
534 | ||
535 | return 0; | |
536 | } | |
537 | ||
538 | /* Start up the event loop. This is the entry point to the event | |
539 | loop. */ | |
540 | ||
541 | void | |
542 | start_event_loop (void) | |
543 | { | |
544 | /* Loop until there is nothing to do. This is the entry point to | |
545 | the event loop engine. If nothing is ready at this time, wait | |
546 | for something to happen (via wait_for_event), then process it. | |
547 | Return when there are no longer event sources to wait for. */ | |
548 | ||
549 | while (1) | |
550 | { | |
551 | /* Any events already waiting in the queue? */ | |
8336d594 PA |
552 | int res = process_event (); |
553 | ||
554 | /* Did the event handler want the event loop to stop? */ | |
555 | if (res == -1) | |
556 | return; | |
557 | ||
558 | if (res) | |
bd99dc85 PA |
559 | continue; |
560 | ||
24b066ba DE |
561 | /* Process any queued callbacks before we go to sleep. */ |
562 | res = process_callback (); | |
563 | ||
564 | /* Did the callback want the event loop to stop? */ | |
565 | if (res == -1) | |
566 | return; | |
567 | ||
568 | if (res) | |
569 | continue; | |
570 | ||
bd99dc85 PA |
571 | /* Wait for a new event. If wait_for_event returns -1, we |
572 | should get out because this means that there are no event | |
573 | sources left. This will make the event loop stop, and the | |
574 | application exit. */ | |
575 | ||
576 | if (wait_for_event () < 0) | |
577 | return; | |
578 | } | |
579 | ||
580 | /* We are done with the event loop. There are no more event sources | |
581 | to listen to. So we exit gdbserver. */ | |
582 | } |