1 /* Event loop machinery for GDB, the GNU debugger.
2 Copyright 1999 Free Software Foundation, Inc.
3 Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 #include "event-loop.h"
22 #include <readline/readline.h>
26 /* For config.h which may define HAVE_POLL */
35 - the first event in the queue is the head of the queue.
36 It will be the next to be serviced.
37 - the last event in the queue
39 Events can be inserted at the front of the queue or at the end of
40 the queue. Events will be extracted from the queue for processing
41 starting from the head. Therefore, events inserted at the head of
42 the queue will be processed in a last in first out fashoin, while
43 those inserted at the tail of the queue will be processed in a first
44 in first out manner. All the fields are NULL if the queue is
49 gdb_event *first_event; /* First pending event */
50 gdb_event *last_event; /* Last pending event */
54 /* Gdb_notifier is just a list of file descriptors gdb is interested in.
55 These are the input file descriptor, and the target file
56 descriptor. We have two flavors of the notifier, one for platforms
57 that have the POLL function, the other for those that don't, and
58 only support SELECT. Each of the elements in the gdb_notifier list is
59 basically a description of what kind of events gdb is interested
62 /* As of 4/30/99 only the input file descriptor is registered with the
66 /* Poll based implementation of the notifier. */
70 /* Ptr to head of file handler list. */
71 file_handler *first_file_handler;
73 /* Ptr to array of pollfd structures. */
74 struct pollfd *poll_fds;
76 /* Number of file descriptors to monitor. */
82 #else /* ! HAVE_POLL */
84 /* Select based implementation of the notifier. */
88 /* Ptr to head of file handler list. */
89 file_handler *first_file_handler;
91 /* Masks to be used in the next call to select.
92 Bits are set in response to calls to create_file_handler. */
93 fd_mask check_masks[3 * MASK_SIZE];
95 /* What file descriptors were found ready by select. */
96 fd_mask ready_masks[3 * MASK_SIZE];
98 /* Number of valid bits (highest fd value + 1). */
104 #endif /* HAVE_POLL */
106 /* All the async_signal_handlers gdb is interested in are kept onto
110 /* Pointer to first in handler list. */
111 async_signal_handler *first_handler;
113 /* Pointer to last in handler list. */
114 async_signal_handler *last_handler;
118 /* Is any of the handlers ready? Check this variable using
119 check_async_ready. This is used by process_event, to determine
120 whether or not to invoke the invoke_async_signal_handler
122 static int async_handler_ready = 0;
124 static void invoke_async_signal_handler PARAMS ((void));
125 static int gdb_wait_for_event PARAMS ((void));
126 static int check_async_ready PARAMS ((void));
127 extern display_gdb_prompt PARAMS ((char *));
130 /* Insert an event object into the gdb event queue at
131 the specified position.
132 POSITION can be head or tail, with values TAIL, HEAD.
133 EVENT_PTR points to the event to be inserted into the queue.
134 The caller must allocate memory for the event. It is freed
135 after the event has ben handled.
136 Events in the queue will be processed head to tail, therefore,
137 events inserted at the head of the queue will be processed
138 as last in first out. Event appended at the tail of the queue
139 will be processed first in first out. */
141 async_queue_event (event_ptr, position)
142 gdb_event *event_ptr;
143 queue_position position;
145 if (position == TAIL)
147 /* The event will become the new last_event. */
149 event_ptr->next_event = NULL;
150 if (event_queue.first_event == NULL)
151 event_queue.first_event = event_ptr;
153 event_queue.last_event->next_event = event_ptr;
154 event_queue.last_event = event_ptr;
156 else if (position == HEAD)
158 /* The event becomes the new first_event. */
160 event_ptr->next_event = event_queue.first_event;
161 if (event_queue.first_event == NULL)
162 event_queue.last_event = event_ptr;
163 event_queue.first_event = event_ptr;
167 /* Process one event.
168 The event can be the next one to be serviced in the event queue,
169 or an asynchronous event handler can be invoked in response to
170 the reception of a signal.
171 If an event was processed (either way), 1 is returned otherwise
173 Scan the queue from head to tail, processing therefore the high
174 priority events first, by invoking the associated event handler
179 gdb_event *event_ptr, *prev_ptr;
180 event_handler_func *proc;
183 /* First let's see if there are any asynchronous event handlers that
184 are ready. These would be the result of invoking any of the
187 if (check_async_ready ())
189 invoke_async_signal_handler ();
193 /* Look in the event queue to find an event that is ready
196 for (event_ptr = event_queue.first_event; event_ptr != NULL;
197 event_ptr = event_ptr->next_event)
199 /* Call the handler for the event. */
201 proc = event_ptr->proc;
204 /* Let's get rid of the event from the event queue. We need to
205 do this now because while processing the event, the proc
206 function could end up calling 'error' and therefore jump out
207 to the caller of this function, gdb_do_one_event. In that
208 case, we would have on the event queue an event wich has been
209 processed, but not deleted. */
211 if (event_queue.first_event == event_ptr)
213 event_queue.first_event = event_ptr->next_event;
214 if (event_ptr->next_event == NULL)
215 event_queue.last_event = NULL;
219 prev_ptr = event_queue.first_event;
220 while (prev_ptr->next_event != event_ptr)
221 prev_ptr = prev_ptr->next_event;
223 prev_ptr->next_event = event_ptr->next_event;
224 if (event_ptr->next_event == NULL)
225 event_queue.last_event = prev_ptr;
227 free ((char *) event_ptr);
229 /* Now call the procedure associted with the event. */
234 /* this is the case if there are no event on the event queue. */
238 /* Process one high level event. If nothing is ready at this time,
239 wait for something to happen (via gdb_wait_for_event), then process
240 it. Returns 1 if something was done otherwise returns 0 (this can
241 happen if there are no event sources to wait for). */
249 if (!SET_TOP_LEVEL ())
251 /* Any events already waiting in the queue? */
252 if (process_event ())
258 /* Wait for a new event. If gdb_wait_for_event returns -1,
259 we should get out because this means that there are no
260 event sources left. This will make the event loop stop,
261 and the application exit. */
263 result = gdb_wait_for_event ();
270 /* Handle any new events occurred while waiting. */
271 if (process_event ())
277 /* If gdb_wait_for_event has returned 1, it means that one
278 event has been handled. We break out of the loop. */
281 } /* end of if !set_top_level */
284 display_gdb_prompt (0);
285 /* Maybe better to set a flag to be checked somewhere as to
286 whether display the prompt or not. */
293 /* Add a file handler/descriptor to the list of descriptors we are
295 FD is the file descriptor for the file/stream to be listened to.
296 For the poll case, MASK is a combination (OR) of
297 POLLIN, POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM,
298 POLLWRBAND: these are the events we are interested in. If any of them
299 occurs, proc should be called.
300 For the select case, MASK is a combination of READABLE, WRITABLE, EXCEPTION.
301 PROC is the procedure that will be called when an event occurs for
302 FD. CLIENT_DATA is the argument to pass to PROC. */
304 create_file_handler (fd, mask, proc, client_data)
307 file_handler_func *proc;
308 gdb_client_data client_data;
310 file_handler *file_ptr;
316 /* Do we already have a file handler for this file? (We may be
317 changing its associated procedure). */
318 for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
319 file_ptr = file_ptr->next_file)
321 if (file_ptr->fd == fd)
325 /* It is a new file descriptor. */
326 if (file_ptr == NULL)
328 file_ptr = (file_handler *) xmalloc (sizeof (file_handler));
330 file_ptr->ready_mask = 0;
331 file_ptr->next_file = gdb_notifier.first_file_handler;
332 gdb_notifier.first_file_handler = file_ptr;
334 file_ptr->proc = proc;
335 file_ptr->client_data = client_data;
336 file_ptr->mask = mask;
340 gdb_notifier.num_fds++;
341 gdb_notifier.poll_fds =
342 (struct pollfd *) realloc (gdb_notifier.poll_fds,
343 (gdb_notifier.num_fds) * sizeof (struct pollfd));
344 (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->fd = fd;
345 (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->events = mask;
346 (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->revents = 0;
348 #else /* ! HAVE_POLL */
350 index = fd / (NBBY * sizeof (fd_mask));
351 bit = 1 << (fd % (NBBY * sizeof (fd_mask)));
353 if (mask & GDB_READABLE)
354 gdb_notifier.check_masks[index] |= bit;
356 gdb_notifier.check_masks[index] &= ~bit;
358 if (mask & GDB_WRITABLE)
359 (gdb_notifier.check_masks + MASK_SIZE)[index] |= bit;
361 (gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit;
363 if (mask & GDB_EXCEPTION)
364 (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] |= bit;
366 (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit;
368 if (gdb_notifier.num_fds <= fd)
369 gdb_notifier.num_fds = fd + 1;
371 #endif /* HAVE_POLL */
374 /* Remove the file descriptor FD from the list of monitored fd's:
375 i.e. we don't care anymore about events on the FD. */
377 delete_file_handler (fd)
380 file_handler *file_ptr, *prev_ptr = NULL;
382 struct pollfd *new_poll_fds;
388 /* Find the entry for the given file. */
390 for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
391 file_ptr = file_ptr->next_file)
393 if (file_ptr->fd == fd)
397 if (file_ptr == NULL)
400 /* Deactivate the file descriptor, by clearing its mask,
401 so that it will not fire again. */
406 /* Create a new poll_fds array by copying every fd's information but the
407 one we want to get rid of. */
410 (struct pollfd *) xmalloc ((gdb_notifier.num_fds - 1) * sizeof (struct pollfd));
412 for (i = 0, j = 0; i < gdb_notifier.num_fds; i++)
414 if ((gdb_notifier.poll_fds + i)->fd != fd)
416 (new_poll_fds + j)->fd = (gdb_notifier.poll_fds + i)->fd;
417 (new_poll_fds + j)->events = (gdb_notifier.poll_fds + i)->events;
418 (new_poll_fds + j)->revents = (gdb_notifier.poll_fds + i)->revents;
422 free (gdb_notifier.poll_fds);
423 gdb_notifier.poll_fds = new_poll_fds;
424 gdb_notifier.num_fds--;
426 #else /* ! HAVE_POLL */
428 index = fd / (NBBY * sizeof (fd_mask));
429 bit = 1 << (fd % (NBBY * sizeof (fd_mask)));
431 if (file_ptr->mask & GDB_READABLE)
432 gdb_notifier.check_masks[index] &= ~bit;
433 if (file_ptr->mask & GDB_WRITABLE)
434 (gdb_notifier.check_masks + MASK_SIZE)[index] &= ~bit;
435 if (file_ptr->mask & GDB_EXCEPTION)
436 (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index] &= ~bit;
438 /* Find current max fd. */
440 if ((fd + 1) == gdb_notifier.num_fds)
442 for (gdb_notifier.num_fds = 0; index >= 0; index--)
444 flags = gdb_notifier.check_masks[index]
445 | (gdb_notifier.check_masks + MASK_SIZE)[index]
446 | (gdb_notifier.check_masks + 2 * (MASK_SIZE))[index];
449 for (i = (NBBY * sizeof (fd_mask)); i > 0; i--)
451 if (flags & (((unsigned long) 1) << (i - 1)))
454 gdb_notifier.num_fds = index * (NBBY * sizeof (fd_mask)) + i;
459 #endif /* HAVE_POLL */
461 /* Get rid of the file handler in the file handler list. */
462 if (file_ptr == gdb_notifier.first_file_handler)
463 gdb_notifier.first_file_handler = file_ptr->next_file;
466 for (prev_ptr = gdb_notifier.first_file_handler;
467 prev_ptr->next_file == file_ptr;
468 prev_ptr = prev_ptr->next_file)
470 prev_ptr->next_file = file_ptr->next_file;
472 free ((char *) file_ptr);
475 /* Handle the given event by calling the procedure associated to the
476 corresponding file handler. Called by process_event indirectly,
477 through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the
478 event in the front of the event queue. */
480 handle_file_event (event_file_desc)
483 file_handler *file_ptr;
484 int mask, error_mask;
486 /* Search the file handler list to find one that matches the fd in
488 for (file_ptr = gdb_notifier.first_file_handler; file_ptr != NULL;
489 file_ptr = file_ptr->next_file)
491 if (file_ptr->fd == event_file_desc)
493 /* With poll, the ready_mask could have any of three events
494 set to 1: POLLHUP, POLLERR, POLLNVAL. These events cannot
495 be used in the requested event mask (events), but they
496 can be returned in the return mask (revents). We need to
497 check for those event too, and add them to the mask which
498 will be passed to the handler. */
500 /* See if the desired events (mask) match the received
501 events (ready_mask). */
504 error_mask = POLLHUP | POLLERR | POLLNVAL;
505 mask = (file_ptr->ready_mask & file_ptr->mask) |
506 (file_ptr->ready_mask & error_mask);
508 #else /* ! HAVE_POLL */
509 mask = file_ptr->ready_mask & file_ptr->mask;
510 #endif /* HAVE_POLL */
512 /* Clear the received events for next time around. */
513 file_ptr->ready_mask = 0;
515 /* If there was a match, then call the handler. */
517 (*file_ptr->proc) (file_ptr->client_data, mask);
523 /* Called by gdb_do_one_event to wait for new events on the
524 monitored file descriptors. Queue file events as they are
525 detected by the poll.
526 If there are no events, this function will block in the
528 Return -1 if there are no files descriptors to monitor,
529 otherwise return 0. */
531 gdb_wait_for_event ()
533 file_handler *file_ptr;
534 gdb_event *file_event_ptr;
538 int mask, bit, index;
541 if (gdb_notifier.num_fds == 0)
546 poll (gdb_notifier.poll_fds, (unsigned long) gdb_notifier.num_fds, -1);
548 #else /* ! HAVE_POLL */
549 memcpy (gdb_notifier.ready_masks,
550 gdb_notifier.check_masks,
551 3 * MASK_SIZE * sizeof (fd_mask));
552 num_found = select (gdb_notifier.num_fds,
553 (SELECT_MASK *) & gdb_notifier.ready_masks[0],
554 (SELECT_MASK *) & gdb_notifier.ready_masks[MASK_SIZE],
555 (SELECT_MASK *) & gdb_notifier.ready_masks[2 * MASK_SIZE],
558 /* Clear the masks after an error from select. */
560 memset (gdb_notifier.ready_masks,
561 0, 3 * MASK_SIZE * sizeof (fd_mask));
563 #endif /* HAVE_POLL */
565 /* Enqueue all detected file events. */
569 for (i = 0; (i < gdb_notifier.num_fds) && (num_found > 0); i++)
571 if ((gdb_notifier.poll_fds + i)->revents)
576 for (file_ptr = gdb_notifier.first_file_handler;
578 file_ptr = file_ptr->next_file)
580 if (file_ptr->fd == (gdb_notifier.poll_fds + i)->fd)
586 /* Enqueue an event only if this is still a new event for
588 if (file_ptr->ready_mask == 0)
591 (gdb_event *) xmalloc (sizeof (gdb_event));
592 file_event_ptr->proc = handle_file_event;
593 file_event_ptr->fd = file_ptr->fd;
594 async_queue_event (file_event_ptr, TAIL);
598 file_ptr->ready_mask = (gdb_notifier.poll_fds + i)->revents;
601 #else /* ! HAVE_POLL */
602 for (file_ptr = gdb_notifier.first_file_handler;
603 (file_ptr != NULL) && (num_found > 0);
604 file_ptr = file_ptr->next_file)
606 index = file_ptr->fd / (NBBY * sizeof (fd_mask));
607 bit = 1 << (file_ptr->fd % (NBBY * sizeof (fd_mask)));
610 if (gdb_notifier.ready_masks[index] & bit)
611 mask |= GDB_READABLE;
612 if ((gdb_notifier.ready_masks + MASK_SIZE)[index] & bit)
613 mask |= GDB_WRITABLE;
614 if ((gdb_notifier.ready_masks + 2 * (MASK_SIZE))[index] & bit)
615 mask |= GDB_EXCEPTION;
622 /* Enqueue an event only if this is still a new event for
625 if (file_ptr->ready_mask == 0)
628 (gdb_event *) xmalloc (sizeof (gdb_event));
629 file_event_ptr->proc = handle_file_event;
630 file_event_ptr->fd = file_ptr->fd;
631 async_queue_event (file_event_ptr, TAIL);
633 file_ptr->ready_mask = mask;
635 #endif /* HAVE_POLL */
641 /* Create an asynchronous handler, allocating memory for it.
642 Return a pointer to the newly created handler.
643 This pointer will be used to invoke the handler by
644 invoke_async_signal_handler.
645 PROC is the function to call with CLIENT_DATA argument
646 whenever the handler is invoked. */
647 async_signal_handler *
648 create_async_signal_handler (proc, client_data)
649 async_handler_func *proc;
650 gdb_client_data client_data;
652 async_signal_handler *async_handler_ptr;
655 (async_signal_handler *) xmalloc (sizeof (async_signal_handler));
656 async_handler_ptr->ready = 0;
657 async_handler_ptr->next_handler = NULL;
658 async_handler_ptr->proc = proc;
659 async_handler_ptr->client_data = client_data;
660 if (sighandler_list.first_handler == NULL)
661 sighandler_list.first_handler = async_handler_ptr;
663 sighandler_list.last_handler->next_handler = async_handler_ptr;
664 sighandler_list.last_handler = async_handler_ptr;
665 return async_handler_ptr;
668 /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information will
669 be used when the handlers are invoked, after we have waited for
670 some event. The caller of this function is the interrupt handler
671 associated with a signal. */
673 mark_async_signal_handler (async_handler_ptr)
674 async_signal_handler *async_handler_ptr;
676 ((async_signal_handler *) async_handler_ptr)->ready = 1;
677 async_handler_ready = 1;
680 /* Call all the handlers that are ready. */
682 invoke_async_signal_handler ()
684 async_signal_handler *async_handler_ptr;
686 if (async_handler_ready == 0)
688 async_handler_ready = 0;
690 /* Invoke ready handlers. */
694 for (async_handler_ptr = sighandler_list.first_handler;
695 async_handler_ptr != NULL;
696 async_handler_ptr = async_handler_ptr->next_handler)
698 if (async_handler_ptr->ready)
701 if (async_handler_ptr == NULL)
703 async_handler_ptr->ready = 0;
704 (*async_handler_ptr->proc) (async_handler_ptr->client_data);
710 /* Delete an asynchronous handler (ASYNC_HANDLER_PTR).
711 Free the space allocated for it. */
713 delete_async_signal_handler (async_handler_ptr)
714 async_signal_handler *async_handler_ptr;
716 async_signal_handler *prev_ptr;
718 if (sighandler_list.first_handler == async_handler_ptr)
720 sighandler_list.first_handler = async_handler_ptr->next_handler;
721 if (sighandler_list.first_handler == NULL)
722 sighandler_list.last_handler = NULL;
726 prev_ptr = sighandler_list.first_handler;
727 while (prev_ptr->next_handler != async_handler_ptr)
728 prev_ptr = prev_ptr->next_handler;
729 prev_ptr->next_handler = async_handler_ptr->next_handler;
730 if (sighandler_list.last_handler == async_handler_ptr)
731 sighandler_list.last_handler = prev_ptr;
733 free ((char *) async_handler_ptr);
736 /* Is it necessary to call invoke_async_signal_handler? */
740 return async_handler_ready;