source: mainline/uspace/lib/posix/signal.c@ d510ac01

lfn serial ticket/834-toolchain-update topic/msim-upgrade topic/simplify-dev-export
Last change on this file since d510ac01 was 55b1efd, checked in by Petr Koupy <petr.koupy@…>, 14 years ago

Minor corrections and unifications of the recently added documentation.
  • Property mode set to 100644
File size: 13.7 KB
Line 
1/*
2 * Copyright (c) 2011 Jiri Zarevucky
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * - The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/** @addtogroup libposix
30 * @{
31 */
32/** @file Signal handling.
33 */
34
35#define LIBPOSIX_INTERNAL
36
37#include "signal.h"
38#include "internal/common.h"
39#include "limits.h"
40#include "stdlib.h"
41#include "string.h"
42#include "errno.h"
43
44#include "libc/fibril_synch.h"
45#include "libc/task.h"
46
47/* This file implements a fairly dumb and incomplete "simulation" of
48 * POSIX signals. Since HelenOS doesn't support signals and mostly doesn't
49 * have any equivalent functionality, most of the signals are useless. The
50 * main purpose of this implementation is thus to help port applications using
51 * signals with minimal modification, but if the application uses signals for
52 * anything non-trivial, it's quite probable it won't work properly even if
53 * it builds without problems.
54 */
55
56/* Used to serialize signal handling. */
57static FIBRIL_MUTEX_INITIALIZE(_signal_mutex);
58
59static LIST_INITIALIZE(_signal_queue);
60
61static posix_sigset_t _signal_mask = 0;
62
63#define DEFAULT_HANDLER { .sa_handler = SIG_DFL, \
64 .sa_mask = 0, .sa_flags = 0, .sa_sigaction = NULL }
65
66/* Actions associated with each signal number. */
67static struct posix_sigaction _signal_actions[_TOP_SIGNAL + 1] = {
68 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
69 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
70 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
71 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
72 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
73 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER,
74 DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER, DEFAULT_HANDLER
75};
76
77/**
78 * Default signal handler. Executes the default action for each signal,
79 * as reasonable within HelenOS.
80 *
81 * @param signo Signal number.
82 */
83void __posix_default_signal_handler(int signo)
84{
85 switch (signo) {
86 case SIGABRT:
87 abort();
88 case SIGQUIT:
89 fprintf(stderr, "Quit signal raised. Exiting.\n");
90 exit(EXIT_FAILURE);
91 case SIGINT:
92 fprintf(stderr, "Interrupt signal caught. Exiting.\n");
93 exit(EXIT_FAILURE);
94 case SIGTERM:
95 fprintf(stderr, "Termination signal caught. Exiting.\n");
96 exit(EXIT_FAILURE);
97 case SIGSTOP:
98 fprintf(stderr, "Stop signal caught, but unsupported. Ignoring.\n");
99 break;
100 case SIGKILL:
101 /* This will only occur when raise or similar is called. */
102 /* Commit suicide. */
103 task_kill(task_get_id());
104
105 /* Should not be reached. */
106 abort();
107 case SIGFPE:
108 case SIGBUS:
109 case SIGILL:
110 case SIGSEGV:
111 posix_psignal(signo, "Hardware exception raised by user code");
112 abort();
113 case SIGSYS:
114 case SIGXCPU:
115 case SIGXFSZ:
116 case SIGTRAP:
117 case SIGHUP:
118 case SIGPIPE:
119 case SIGPOLL:
120 case SIGURG:
121 case SIGTSTP:
122 case SIGTTIN:
123 case SIGTTOU:
124 posix_psignal(signo, "Unsupported signal caught");
125 abort();
126 case SIGCHLD:
127 case SIGUSR1:
128 case SIGUSR2:
129 case SIGALRM:
130 case SIGVTALRM:
131 case SIGPROF:
132 case SIGCONT:
133 /* ignored */
134 break;
135 }
136}
137
138/**
139 * Just an empty function to get an unique pointer value for comparison.
140 *
141 * @param signo Signal number.
142 */
143void __posix_hold_signal_handler(int signo)
144{
145 /* Nothing */
146}
147
148/**
149 * Empty function to be used as ignoring handler.
150 *
151 * @param signo Signal number.
152 */
153void __posix_ignore_signal_handler(int signo)
154{
155 /* Nothing */
156}
157
158/**
159 * Clear the signal set.
160 *
161 * @param set Pointer to the signal set.
162 * @return Always returns zero.
163 */
164int posix_sigemptyset(posix_sigset_t *set)
165{
166 assert(set != NULL);
167
168 *set = 0;
169 return 0;
170}
171
172/**
173 * Fill the signal set (i.e. add all signals).
174 *
175 * @param set Pointer to the signal set.
176 * @return Always returns zero.
177 */
178int posix_sigfillset(posix_sigset_t *set)
179{
180 assert(set != NULL);
181
182 *set = UINT32_MAX;
183 return 0;
184}
185
186/**
187 * Add a signal to the set.
188 *
189 * @param set Pointer to the signal set.
190 * @param signo Signal number to add.
191 * @return Always returns zero.
192 */
193int posix_sigaddset(posix_sigset_t *set, int signo)
194{
195 assert(set != NULL);
196
197 *set |= (1 << signo);
198 return 0;
199}
200
201/**
202 * Delete a signal from the set.
203 *
204 * @param set Pointer to the signal set.
205 * @param signo Signal number to remove.
206 * @return Always returns zero.
207 */
208int posix_sigdelset(posix_sigset_t *set, int signo)
209{
210 assert(set != NULL);
211
212 *set &= ~(1 << signo);
213 return 0;
214}
215
216/**
217 * Inclusion test for a signal set.
218 *
219 * @param set Pointer to the signal set.
220 * @param signo Signal number to query.
221 * @return 1 if the signal is in the set, 0 otherwise.
222 */
223int posix_sigismember(const posix_sigset_t *set, int signo)
224{
225 assert(set != NULL);
226
227 return (*set & (1 << signo)) != 0;
228}
229
230/**
231 * Unsafe variant of the sigaction() function.
232 * Doesn't do any checking of its arguments and
233 * does not deal with thread-safety.
234 *
235 * @param sig
236 * @param act
237 * @param oact
238 */
239static void _sigaction_unsafe(int sig, const struct posix_sigaction *restrict act,
240 struct posix_sigaction *restrict oact)
241{
242 if (oact != NULL) {
243 memcpy(oact, &_signal_actions[sig],
244 sizeof(struct posix_sigaction));
245 }
246
247 if (act != NULL) {
248 memcpy(&_signal_actions[sig], act,
249 sizeof(struct posix_sigaction));
250 }
251}
252
253/**
254 * Sets a new action for the given signal number.
255 *
256 * @param sig Signal number to set action for.
257 * @param act If not NULL, contents of this structure are
258 * used as the new action for the signal.
259 * @param oact If not NULL, the original action associated with the signal
260 * is stored in the structure pointer to.
261 * @return -1 with errno set on failure, 0 on success.
262 */
263int posix_sigaction(int sig, const struct posix_sigaction *restrict act,
264 struct posix_sigaction *restrict oact)
265{
266 if (sig > _TOP_SIGNAL || (act != NULL &&
267 (sig == SIGKILL || sig == SIGSTOP))) {
268 errno = EINVAL;
269 return -1;
270 }
271
272 if (sig > _TOP_CATCHABLE_SIGNAL) {
273 posix_psignal(sig,
274 "WARNING: registering handler for a partially"
275 " or fully unsupported signal. This handler may only be"
276 " invoked by the raise() function, which may not be what"
277 " the application developer intended");
278 }
279
280 fibril_mutex_lock(&_signal_mutex);
281 _sigaction_unsafe(sig, act, oact);
282 fibril_mutex_unlock(&_signal_mutex);
283
284 return 0;
285}
286
287/**
288 * Sets a new handler for the given signal number.
289 *
290 * @param sig Signal number to set handler for.
291 * @param func Handler function.
292 * @return SIG_ERR on failure, original handler on success.
293 */
294void (*posix_signal(int sig, void (*func)(int)))(int)
295{
296 struct posix_sigaction new = {
297 .sa_handler = func,
298 .sa_mask = 0,
299 .sa_flags = 0,
300 .sa_sigaction = NULL
301 };
302 struct posix_sigaction old;
303 if (posix_sigaction(sig, func == NULL ? NULL : &new, &old) == 0) {
304 return old.sa_handler;
305 } else {
306 return SIG_ERR;
307 }
308}
309
310typedef struct {
311 link_t link;
312 int signo;
313 posix_siginfo_t siginfo;
314} signal_queue_item;
315
316/**
317 * Queue blocked signal.
318 *
319 * @param signo Signal number.
320 * @param siginfo Additional information about the signal.
321 */
322static void _queue_signal(int signo, posix_siginfo_t *siginfo)
323{
324 assert(signo >= 0 && signo <= _TOP_SIGNAL);
325 assert(siginfo != NULL);
326
327 signal_queue_item *item = malloc(sizeof(signal_queue_item));
328 link_initialize(&(item->link));
329 item->signo = signo;
330 memcpy(&item->siginfo, siginfo, sizeof(posix_siginfo_t));
331 list_append(&(item->link), &_signal_queue);
332}
333
334
335/**
336 * Executes an action associated with the given signal.
337 *
338 * @param signo Signal number.
339 * @param siginfo Additional information about the circumstances of this raise.
340 * @return 0 if the action has been successfully executed. -1 if the signal is
341 * blocked.
342 */
343static int _raise_sigaction(int signo, posix_siginfo_t *siginfo)
344{
345 assert(signo >= 0 && signo <= _TOP_SIGNAL);
346 assert(siginfo != NULL);
347
348 fibril_mutex_lock(&_signal_mutex);
349
350 struct posix_sigaction action = _signal_actions[signo];
351
352 if (posix_sigismember(&_signal_mask, signo) ||
353 action.sa_handler == SIG_HOLD) {
354 _queue_signal(signo, siginfo);
355 fibril_mutex_unlock(&_signal_mutex);
356 return -1;
357 }
358
359 /* Modifying signal mask is unnecessary,
360 * signal handling is serialized.
361 */
362
363 if ((action.sa_flags & SA_RESETHAND) && signo != SIGILL && signo != SIGTRAP) {
364 _signal_actions[signo] = (struct posix_sigaction) DEFAULT_HANDLER;
365 }
366
367 if (action.sa_flags & SA_SIGINFO) {
368 assert(action.sa_sigaction != NULL);
369 action.sa_sigaction(signo, siginfo, NULL);
370 } else {
371 assert(action.sa_handler != NULL);
372 action.sa_handler(signo);
373 }
374
375 fibril_mutex_unlock(&_signal_mutex);
376
377 return 0;
378}
379
380/**
381 * Raise all unblocked previously queued signals.
382 */
383static void _dequeue_unblocked_signals()
384{
385 link_t *iterator = _signal_queue.head.next;
386 link_t *next;
387
388 while (iterator != &(_signal_queue).head) {
389 next = iterator->next;
390
391 signal_queue_item *item =
392 list_get_instance(iterator, signal_queue_item, link);
393
394 if (!posix_sigismember(&_signal_mask, item->signo) &&
395 _signal_actions[item->signo].sa_handler != SIG_HOLD) {
396 list_remove(&(item->link));
397 _raise_sigaction(item->signo, &(item->siginfo));
398 free(item);
399 }
400
401 iterator = next;
402 }
403}
404
405/**
406 * Raise a signal for the calling process.
407 *
408 * @param sig Signal number.
409 * @return -1 with errno set on failure, 0 on success.
410 */
411int posix_raise(int sig)
412{
413 if (sig >= 0 && sig <= _TOP_SIGNAL) {
414 posix_siginfo_t siginfo = {
415 .si_signo = sig,
416 .si_code = SI_USER
417 };
418 return _raise_sigaction(sig, &siginfo);
419 } else {
420 errno = EINVAL;
421 return -1;
422 }
423}
424
425/**
426 * Raises a signal for a selected process.
427 *
428 * @param pid PID of the process for which the signal shall be raised.
429 * @param signo Signal to raise.
430 * @return -1 with errno set on failure (possible errors include unsupported
431 * action, invalid signal number, lack of permissions, etc.), 0 on success.
432 */
433int posix_kill(posix_pid_t pid, int signo)
434{
435 if (pid < 1) {
436 // TODO
437 errno = ENOTSUP;
438 return -1;
439 }
440
441 if (signo > _TOP_SIGNAL) {
442 errno = EINVAL;
443 return -1;
444 }
445
446 if (pid == (posix_pid_t) task_get_id()) {
447 return posix_raise(signo);
448 }
449
450 switch (signo) {
451 case SIGKILL:
452 task_kill(pid);
453 break;
454 default:
455 /* Nothing else supported yet. */
456 errno = ENOTSUP;
457 return -1;
458 }
459
460 return 0;
461}
462
463/**
464 * Send a signal to a process group. Always fails at the moment because of
465 * lack of this functionality in HelenOS.
466 *
467 * @param pid PID of the process group.
468 * @param sig Signal number.
469 * @return -1 on failure, 0 on success (see kill()).
470 */
471int posix_killpg(posix_pid_t pid, int sig)
472{
473 assert(pid > 1);
474 return posix_kill(-pid, sig);
475}
476
477/**
478 * Outputs information about the signal to the standard error stream.
479 *
480 * @param pinfo SigInfo struct to write.
481 * @param message String to output alongside human-readable signal description.
482 */
483void posix_psiginfo(const posix_siginfo_t *pinfo, const char *message)
484{
485 assert(pinfo != NULL);
486 posix_psignal(pinfo->si_signo, message);
487 // TODO: print si_code
488}
489
490/**
491 * Outputs information about the signal to the standard error stream.
492 *
493 * @param signum Signal number.
494 * @param message String to output alongside human-readable signal description.
495 */
496void posix_psignal(int signum, const char *message)
497{
498 char *sigmsg = posix_strsignal(signum);
499 if (message == NULL || *message == '\0') {
500 fprintf(stderr, "%s\n", sigmsg);
501 } else {
502 fprintf(stderr, "%s: %s\n", message, sigmsg);
503 }
504}
505
506/**
507 * Manipulate the signal mask of the calling thread.
508 *
509 * @param how What to do with the mask.
510 * @param set Signal set to work with.
511 * @param oset If not NULL, the original signal mask is coppied here.
512 * @return 0 success, errorcode on failure.
513 */
514int posix_thread_sigmask(int how, const posix_sigset_t *restrict set,
515 posix_sigset_t *restrict oset)
516{
517 fibril_mutex_lock(&_signal_mutex);
518
519 if (oset != NULL) {
520 *oset = _signal_mask;
521 }
522 if (set != NULL) {
523 switch (how) {
524 case SIG_BLOCK:
525 _signal_mask |= *set;
526 break;
527 case SIG_UNBLOCK:
528 _signal_mask &= ~*set;
529 break;
530 case SIG_SETMASK:
531 _signal_mask = *set;
532 break;
533 default:
534 fibril_mutex_unlock(&_signal_mutex);
535 return EINVAL;
536 }
537 }
538
539 _dequeue_unblocked_signals();
540
541 fibril_mutex_unlock(&_signal_mutex);
542
543 return 0;
544}
545
546/**
547 * Manipulate the signal mask of the process.
548 *
549 * @param how What to do with the mask.
550 * @param set Signal set to work with.
551 * @param oset If not NULL, the original signal mask is coppied here.
552 * @return 0 on success, -1 with errno set on failure.
553 */
554int posix_sigprocmask(int how, const posix_sigset_t *restrict set,
555 posix_sigset_t *restrict oset)
556{
557 int result = posix_thread_sigmask(how, set, oset);
558 if (result != 0) {
559 errno = result;
560 return -1;
561 }
562 return 0;
563}
564
565/** @}
566 */
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