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. */
23 #include "event-loop.h"
27 #include <sys/types.h>
33 - the first event in the queue is the head of the queue.
34 It will be the next to be serviced.
35 - the last event in the queue
37 Events can be inserted at the front of the queue or at the end of
38 the queue. Events will be extracted from the queue for processing
39 starting from the head. Therefore, events inserted at the head of
40 the queue will be processed in a last in first out fashoin, while
41 those inserted at the tail of the queue will be processed in a first
42 in first out manner. All the fields are NULL if the queue is
47 gdb_event
*first_event
; /* First pending event */
48 gdb_event
*last_event
; /* Last pending event */
52 /* Gdb_notifier is just a list of file descriptors gdb is interested in.
53 These are the input file descriptor, and the target file
54 descriptor. We have two flavors of the notifier, one for platforms
55 that have the POLL function, the other for those that don't, and
56 only support SELECT. Each of the elements in the gdb_notifier list is
57 basically a description of what kind of events gdb is interested
60 /* As of 1999-04-30 only the input file descriptor is registered with the
64 /* Poll based implementation of the notifier. */
68 /* Ptr to head of file handler list. */
69 file_handler
*first_file_handler
;
71 /* Ptr to array of pollfd structures. */
72 struct pollfd
*poll_fds
;
74 /* Number of file descriptors to monitor. */
80 #else /* ! HAVE_POLL */
82 /* Select based implementation of the notifier. */
86 /* Ptr to head of file handler list. */
87 file_handler
*first_file_handler
;
89 /* Masks to be used in the next call to select.
90 Bits are set in response to calls to create_file_handler. */
91 fd_mask check_masks
[3 * MASK_SIZE
];
93 /* What file descriptors were found ready by select. */
94 fd_mask ready_masks
[3 * MASK_SIZE
];
96 /* Number of valid bits (highest fd value + 1). */
102 #endif /* HAVE_POLL */
104 /* All the async_signal_handlers gdb is interested in are kept onto
108 /* Pointer to first in handler list. */
109 async_signal_handler
*first_handler
;
111 /* Pointer to last in handler list. */
112 async_signal_handler
*last_handler
;
116 /* Is any of the handlers ready? Check this variable using
117 check_async_ready. This is used by process_event, to determine
118 whether or not to invoke the invoke_async_signal_handler
120 static int async_handler_ready
= 0;
122 static void create_file_handler
PARAMS ((int, int, file_handler_func
*, gdb_client_data
));
123 static void invoke_async_signal_handler
PARAMS ((void));
124 static int gdb_wait_for_event
PARAMS ((void));
125 static int gdb_do_one_event
PARAMS ((void));
126 static int check_async_ready
PARAMS ((void));
129 /* Insert an event object into the gdb event queue at
130 the specified position.
131 POSITION can be head or tail, with values TAIL, HEAD.
132 EVENT_PTR points to the event to be inserted into the queue.
133 The caller must allocate memory for the event. It is freed
134 after the event has ben handled.
135 Events in the queue will be processed head to tail, therefore,
136 events inserted at the head of the queue will be processed
137 as last in first out. Event appended at the tail of the queue
138 will be processed first in first out. */
140 async_queue_event (event_ptr
, position
)
141 gdb_event
*event_ptr
;
142 queue_position position
;
144 if (position
== TAIL
)
146 /* The event will become the new last_event. */
148 event_ptr
->next_event
= NULL
;
149 if (event_queue
.first_event
== NULL
)
150 event_queue
.first_event
= event_ptr
;
152 event_queue
.last_event
->next_event
= event_ptr
;
153 event_queue
.last_event
= event_ptr
;
155 else if (position
== HEAD
)
157 /* The event becomes the new first_event. */
159 event_ptr
->next_event
= event_queue
.first_event
;
160 if (event_queue
.first_event
== NULL
)
161 event_queue
.last_event
= event_ptr
;
162 event_queue
.first_event
= event_ptr
;
166 /* Process one event.
167 The event can be the next one to be serviced in the event queue,
168 or an asynchronous event handler can be invoked in response to
169 the reception of a signal.
170 If an event was processed (either way), 1 is returned otherwise
172 Scan the queue from head to tail, processing therefore the high
173 priority events first, by invoking the associated event handler
178 gdb_event
*event_ptr
, *prev_ptr
;
179 event_handler_func
*proc
;
182 /* First let's see if there are any asynchronous event handlers that
183 are ready. These would be the result of invoking any of the
186 if (check_async_ready ())
188 invoke_async_signal_handler ();
192 /* Look in the event queue to find an event that is ready
195 for (event_ptr
= event_queue
.first_event
; event_ptr
!= NULL
;
196 event_ptr
= event_ptr
->next_event
)
198 /* Call the handler for the event. */
200 proc
= event_ptr
->proc
;
203 /* Let's get rid of the event from the event queue. We need to
204 do this now because while processing the event, the proc
205 function could end up calling 'error' and therefore jump out
206 to the caller of this function, gdb_do_one_event. In that
207 case, we would have on the event queue an event wich has been
208 processed, but not deleted. */
210 if (event_queue
.first_event
== event_ptr
)
212 event_queue
.first_event
= event_ptr
->next_event
;
213 if (event_ptr
->next_event
== NULL
)
214 event_queue
.last_event
= NULL
;
218 prev_ptr
= event_queue
.first_event
;
219 while (prev_ptr
->next_event
!= event_ptr
)
220 prev_ptr
= prev_ptr
->next_event
;
222 prev_ptr
->next_event
= event_ptr
->next_event
;
223 if (event_ptr
->next_event
== NULL
)
224 event_queue
.last_event
= prev_ptr
;
226 free ((char *) event_ptr
);
228 /* Now call the procedure associted with the event. */
233 /* this is the case if there are no event on the event queue. */
237 /* Process one high level event. If nothing is ready at this time,
238 wait for something to happen (via gdb_wait_for_event), then process
239 it. Returns 1 if something was done otherwise returns 0 (this can
240 happen if there are no event sources to wait for). */
248 if (!SET_TOP_LEVEL ())
250 /* Any events already waiting in the queue? */
251 if (process_event ())
257 /* Wait for a new event. If gdb_wait_for_event returns -1,
258 we should get out because this means that there are no
259 event sources left. This will make the event loop stop,
260 and the application exit. */
262 result
= gdb_wait_for_event ();
269 /* Handle any new events occurred while waiting. */
270 if (process_event ())
276 /* If gdb_wait_for_event has returned 1, it means that one
277 event has been handled. We break out of the loop. */
280 } /* end of if !set_top_level */
283 /* FIXME: this should really be a call to a hook that is
284 interface specific, because interfaces can display the
285 prompt in their own way. */
286 display_gdb_prompt (0);
287 /* Maybe better to set a flag to be checked somewhere as to
288 whether display the prompt or not. */
295 /* Start up the event loop. This is the entry point to the event loop
296 from the command loop. */
300 /* Loop until there is something to do. This is the entry point to
301 the event loop engine. gdb_do_one_event will process one event
302 for each invocation. It always returns 1, unless there are no
303 more event sources registered. In this case it returns 0. */
304 while (gdb_do_one_event () != 0)
307 /* We are done with the event loop. There are no more event sources
308 to listen to. So we exit GDB. */
314 /* Wrapper function for create_file_handler, so that the caller
315 doesn't have to know implementation details about the use of poll
318 add_file_handler (fd
, proc
, client_data
)
320 file_handler_func
*proc
;
321 gdb_client_data client_data
;
324 create_file_handler (fd
, POLLIN
, (file_handler_func
*) proc
, client_data
);
326 create_file_handler (fd
, GDB_READABLE
, (file_handler_func
*) proc
, client_data
);
330 /* Add a file handler/descriptor to the list of descriptors we are
332 FD is the file descriptor for the file/stream to be listened to.
333 For the poll case, MASK is a combination (OR) of
334 POLLIN, POLLRDNORM, POLLRDBAND, POLLPRI, POLLOUT, POLLWRNORM,
335 POLLWRBAND: these are the events we are interested in. If any of them
336 occurs, proc should be called.
337 For the select case, MASK is a combination of READABLE, WRITABLE, EXCEPTION.
338 PROC is the procedure that will be called when an event occurs for
339 FD. CLIENT_DATA is the argument to pass to PROC. */
341 create_file_handler (fd
, mask
, proc
, client_data
)
344 file_handler_func
*proc
;
345 gdb_client_data client_data
;
347 file_handler
*file_ptr
;
353 /* Do we already have a file handler for this file? (We may be
354 changing its associated procedure). */
355 for (file_ptr
= gdb_notifier
.first_file_handler
; file_ptr
!= NULL
;
356 file_ptr
= file_ptr
->next_file
)
358 if (file_ptr
->fd
== fd
)
362 /* It is a new file descriptor. */
363 if (file_ptr
== NULL
)
365 file_ptr
= (file_handler
*) xmalloc (sizeof (file_handler
));
367 file_ptr
->ready_mask
= 0;
368 file_ptr
->next_file
= gdb_notifier
.first_file_handler
;
369 gdb_notifier
.first_file_handler
= file_ptr
;
371 file_ptr
->proc
= proc
;
372 file_ptr
->client_data
= client_data
;
373 file_ptr
->mask
= mask
;
377 gdb_notifier
.num_fds
++;
378 if (gdb_notifier
.poll_fds
)
379 gdb_notifier
.poll_fds
=
380 (struct pollfd
*) realloc (gdb_notifier
.poll_fds
,
381 (gdb_notifier
.num_fds
) * sizeof (struct pollfd
));
383 gdb_notifier
.poll_fds
=
384 (struct pollfd
*) xmalloc (sizeof (struct pollfd
));
385 (gdb_notifier
.poll_fds
+ gdb_notifier
.num_fds
- 1)->fd
= fd
;
386 (gdb_notifier
.poll_fds
+ gdb_notifier
.num_fds
- 1)->events
= mask
;
387 (gdb_notifier
.poll_fds
+ gdb_notifier
.num_fds
- 1)->revents
= 0;
389 #else /* ! HAVE_POLL */
391 index
= fd
/ (NBBY
* sizeof (fd_mask
));
392 bit
= 1 << (fd
% (NBBY
* sizeof (fd_mask
)));
394 if (mask
& GDB_READABLE
)
395 gdb_notifier
.check_masks
[index
] |= bit
;
397 gdb_notifier
.check_masks
[index
] &= ~bit
;
399 if (mask
& GDB_WRITABLE
)
400 (gdb_notifier
.check_masks
+ MASK_SIZE
)[index
] |= bit
;
402 (gdb_notifier
.check_masks
+ MASK_SIZE
)[index
] &= ~bit
;
404 if (mask
& GDB_EXCEPTION
)
405 (gdb_notifier
.check_masks
+ 2 * (MASK_SIZE
))[index
] |= bit
;
407 (gdb_notifier
.check_masks
+ 2 * (MASK_SIZE
))[index
] &= ~bit
;
409 if (gdb_notifier
.num_fds
<= fd
)
410 gdb_notifier
.num_fds
= fd
+ 1;
412 #endif /* HAVE_POLL */
415 /* Remove the file descriptor FD from the list of monitored fd's:
416 i.e. we don't care anymore about events on the FD. */
418 delete_file_handler (fd
)
421 file_handler
*file_ptr
, *prev_ptr
= NULL
;
423 struct pollfd
*new_poll_fds
;
429 /* Find the entry for the given file. */
431 for (file_ptr
= gdb_notifier
.first_file_handler
; file_ptr
!= NULL
;
432 file_ptr
= file_ptr
->next_file
)
434 if (file_ptr
->fd
== fd
)
438 if (file_ptr
== NULL
)
441 /* Deactivate the file descriptor, by clearing its mask,
442 so that it will not fire again. */
447 /* Create a new poll_fds array by copying every fd's information but the
448 one we want to get rid of. */
451 (struct pollfd
*) xmalloc ((gdb_notifier
.num_fds
- 1) * sizeof (struct pollfd
));
453 for (i
= 0, j
= 0; i
< gdb_notifier
.num_fds
; i
++)
455 if ((gdb_notifier
.poll_fds
+ i
)->fd
!= fd
)
457 (new_poll_fds
+ j
)->fd
= (gdb_notifier
.poll_fds
+ i
)->fd
;
458 (new_poll_fds
+ j
)->events
= (gdb_notifier
.poll_fds
+ i
)->events
;
459 (new_poll_fds
+ j
)->revents
= (gdb_notifier
.poll_fds
+ i
)->revents
;
463 free (gdb_notifier
.poll_fds
);
464 gdb_notifier
.poll_fds
= new_poll_fds
;
465 gdb_notifier
.num_fds
--;
467 #else /* ! HAVE_POLL */
469 index
= fd
/ (NBBY
* sizeof (fd_mask
));
470 bit
= 1 << (fd
% (NBBY
* sizeof (fd_mask
)));
472 if (file_ptr
->mask
& GDB_READABLE
)
473 gdb_notifier
.check_masks
[index
] &= ~bit
;
474 if (file_ptr
->mask
& GDB_WRITABLE
)
475 (gdb_notifier
.check_masks
+ MASK_SIZE
)[index
] &= ~bit
;
476 if (file_ptr
->mask
& GDB_EXCEPTION
)
477 (gdb_notifier
.check_masks
+ 2 * (MASK_SIZE
))[index
] &= ~bit
;
479 /* Find current max fd. */
481 if ((fd
+ 1) == gdb_notifier
.num_fds
)
483 for (gdb_notifier
.num_fds
= 0; index
>= 0; index
--)
485 flags
= gdb_notifier
.check_masks
[index
]
486 | (gdb_notifier
.check_masks
+ MASK_SIZE
)[index
]
487 | (gdb_notifier
.check_masks
+ 2 * (MASK_SIZE
))[index
];
490 for (i
= (NBBY
* sizeof (fd_mask
)); i
> 0; i
--)
492 if (flags
& (((unsigned long) 1) << (i
- 1)))
495 gdb_notifier
.num_fds
= index
* (NBBY
* sizeof (fd_mask
)) + i
;
500 #endif /* HAVE_POLL */
502 /* Get rid of the file handler in the file handler list. */
503 if (file_ptr
== gdb_notifier
.first_file_handler
)
504 gdb_notifier
.first_file_handler
= file_ptr
->next_file
;
507 for (prev_ptr
= gdb_notifier
.first_file_handler
;
508 prev_ptr
->next_file
!= file_ptr
;
509 prev_ptr
= prev_ptr
->next_file
)
511 prev_ptr
->next_file
= file_ptr
->next_file
;
513 free ((char *) file_ptr
);
516 /* Handle the given event by calling the procedure associated to the
517 corresponding file handler. Called by process_event indirectly,
518 through event_ptr->proc. EVENT_FILE_DESC is file descriptor of the
519 event in the front of the event queue. */
521 handle_file_event (event_file_desc
)
524 file_handler
*file_ptr
;
525 int mask
, error_mask
;
527 /* Search the file handler list to find one that matches the fd in
529 for (file_ptr
= gdb_notifier
.first_file_handler
; file_ptr
!= NULL
;
530 file_ptr
= file_ptr
->next_file
)
532 if (file_ptr
->fd
== event_file_desc
)
534 /* With poll, the ready_mask could have any of three events
535 set to 1: POLLHUP, POLLERR, POLLNVAL. These events cannot
536 be used in the requested event mask (events), but they
537 can be returned in the return mask (revents). We need to
538 check for those event too, and add them to the mask which
539 will be passed to the handler. */
541 /* See if the desired events (mask) match the received
542 events (ready_mask). */
545 error_mask
= POLLHUP
| POLLERR
| POLLNVAL
;
546 mask
= (file_ptr
->ready_mask
& file_ptr
->mask
) |
547 (file_ptr
->ready_mask
& error_mask
);
549 #else /* ! HAVE_POLL */
550 mask
= file_ptr
->ready_mask
& file_ptr
->mask
;
551 #endif /* HAVE_POLL */
553 /* Clear the received events for next time around. */
554 file_ptr
->ready_mask
= 0;
556 /* If there was a match, then call the handler. */
558 (*file_ptr
->proc
) (file_ptr
->client_data
, mask
);
564 /* Called by gdb_do_one_event to wait for new events on the
565 monitored file descriptors. Queue file events as they are
566 detected by the poll.
567 If there are no events, this function will block in the
569 Return -1 if there are no files descriptors to monitor,
570 otherwise return 0. */
572 gdb_wait_for_event ()
574 file_handler
*file_ptr
;
575 gdb_event
*file_event_ptr
;
580 int mask
, bit
, index
;
583 if (gdb_notifier
.num_fds
== 0)
588 poll (gdb_notifier
.poll_fds
, (unsigned long) gdb_notifier
.num_fds
, -1);
590 #else /* ! HAVE_POLL */
591 memcpy (gdb_notifier
.ready_masks
,
592 gdb_notifier
.check_masks
,
593 3 * MASK_SIZE
* sizeof (fd_mask
));
594 num_found
= select (gdb_notifier
.num_fds
,
595 (SELECT_MASK
*) & gdb_notifier
.ready_masks
[0],
596 (SELECT_MASK
*) & gdb_notifier
.ready_masks
[MASK_SIZE
],
597 (SELECT_MASK
*) & gdb_notifier
.ready_masks
[2 * MASK_SIZE
],
600 /* Clear the masks after an error from select. */
602 memset (gdb_notifier
.ready_masks
,
603 0, 3 * MASK_SIZE
* sizeof (fd_mask
));
605 #endif /* HAVE_POLL */
607 /* Enqueue all detected file events. */
611 for (i
= 0; (i
< gdb_notifier
.num_fds
) && (num_found
> 0); i
++)
613 if ((gdb_notifier
.poll_fds
+ i
)->revents
)
618 for (file_ptr
= gdb_notifier
.first_file_handler
;
620 file_ptr
= file_ptr
->next_file
)
622 if (file_ptr
->fd
== (gdb_notifier
.poll_fds
+ i
)->fd
)
628 /* Enqueue an event only if this is still a new event for
630 if (file_ptr
->ready_mask
== 0)
633 (gdb_event
*) xmalloc (sizeof (gdb_event
));
634 file_event_ptr
->proc
= handle_file_event
;
635 file_event_ptr
->fd
= file_ptr
->fd
;
636 async_queue_event (file_event_ptr
, TAIL
);
640 file_ptr
->ready_mask
= (gdb_notifier
.poll_fds
+ i
)->revents
;
643 #else /* ! HAVE_POLL */
644 for (file_ptr
= gdb_notifier
.first_file_handler
;
645 (file_ptr
!= NULL
) && (num_found
> 0);
646 file_ptr
= file_ptr
->next_file
)
648 index
= file_ptr
->fd
/ (NBBY
* sizeof (fd_mask
));
649 bit
= 1 << (file_ptr
->fd
% (NBBY
* sizeof (fd_mask
)));
652 if (gdb_notifier
.ready_masks
[index
] & bit
)
653 mask
|= GDB_READABLE
;
654 if ((gdb_notifier
.ready_masks
+ MASK_SIZE
)[index
] & bit
)
655 mask
|= GDB_WRITABLE
;
656 if ((gdb_notifier
.ready_masks
+ 2 * (MASK_SIZE
))[index
] & bit
)
657 mask
|= GDB_EXCEPTION
;
664 /* Enqueue an event only if this is still a new event for
667 if (file_ptr
->ready_mask
== 0)
670 (gdb_event
*) xmalloc (sizeof (gdb_event
));
671 file_event_ptr
->proc
= handle_file_event
;
672 file_event_ptr
->fd
= file_ptr
->fd
;
673 async_queue_event (file_event_ptr
, TAIL
);
675 file_ptr
->ready_mask
= mask
;
677 #endif /* HAVE_POLL */
683 /* Create an asynchronous handler, allocating memory for it.
684 Return a pointer to the newly created handler.
685 This pointer will be used to invoke the handler by
686 invoke_async_signal_handler.
687 PROC is the function to call with CLIENT_DATA argument
688 whenever the handler is invoked. */
689 async_signal_handler
*
690 create_async_signal_handler (proc
, client_data
)
691 async_handler_func
*proc
;
692 gdb_client_data client_data
;
694 async_signal_handler
*async_handler_ptr
;
697 (async_signal_handler
*) xmalloc (sizeof (async_signal_handler
));
698 async_handler_ptr
->ready
= 0;
699 async_handler_ptr
->next_handler
= NULL
;
700 async_handler_ptr
->proc
= proc
;
701 async_handler_ptr
->client_data
= client_data
;
702 if (sighandler_list
.first_handler
== NULL
)
703 sighandler_list
.first_handler
= async_handler_ptr
;
705 sighandler_list
.last_handler
->next_handler
= async_handler_ptr
;
706 sighandler_list
.last_handler
= async_handler_ptr
;
707 return async_handler_ptr
;
710 /* Mark the handler (ASYNC_HANDLER_PTR) as ready. This information will
711 be used when the handlers are invoked, after we have waited for
712 some event. The caller of this function is the interrupt handler
713 associated with a signal. */
715 mark_async_signal_handler (async_handler_ptr
)
716 async_signal_handler
*async_handler_ptr
;
718 ((async_signal_handler
*) async_handler_ptr
)->ready
= 1;
719 async_handler_ready
= 1;
722 /* Call all the handlers that are ready. */
724 invoke_async_signal_handler ()
726 async_signal_handler
*async_handler_ptr
;
728 if (async_handler_ready
== 0)
730 async_handler_ready
= 0;
732 /* Invoke ready handlers. */
736 for (async_handler_ptr
= sighandler_list
.first_handler
;
737 async_handler_ptr
!= NULL
;
738 async_handler_ptr
= async_handler_ptr
->next_handler
)
740 if (async_handler_ptr
->ready
)
743 if (async_handler_ptr
== NULL
)
745 async_handler_ptr
->ready
= 0;
746 (*async_handler_ptr
->proc
) (async_handler_ptr
->client_data
);
752 /* Delete an asynchronous handler (ASYNC_HANDLER_PTR).
753 Free the space allocated for it. */
755 delete_async_signal_handler (async_handler_ptr
)
756 async_signal_handler
**async_handler_ptr
;
758 async_signal_handler
*prev_ptr
;
760 if (sighandler_list
.first_handler
== (*async_handler_ptr
))
762 sighandler_list
.first_handler
= (*async_handler_ptr
)->next_handler
;
763 if (sighandler_list
.first_handler
== NULL
)
764 sighandler_list
.last_handler
= NULL
;
768 prev_ptr
= sighandler_list
.first_handler
;
769 while (prev_ptr
->next_handler
!= (*async_handler_ptr
) && prev_ptr
)
770 prev_ptr
= prev_ptr
->next_handler
;
771 prev_ptr
->next_handler
= (*async_handler_ptr
)->next_handler
;
772 if (sighandler_list
.last_handler
== (*async_handler_ptr
))
773 sighandler_list
.last_handler
= prev_ptr
;
775 free ((char *) (*async_handler_ptr
));
776 (*async_handler_ptr
) = NULL
;
779 /* Is it necessary to call invoke_async_signal_handler? */
783 return async_handler_ready
;