1 /* $OpenBSD: kqueue.c,v 1.5 2002/07/10 14:41:31 art Exp $ */
2
3 /*
4 * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu>
5 * Copyright 2007-2012 Niels Provos and Nick Mathewson
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29 #include "event2/event-config.h"
30
31 #define _GNU_SOURCE
32
33 #include <sys/types.h>
34 #ifdef _EVENT_HAVE_SYS_TIME_H
35 #include <sys/time.h>
36 #endif
37 #include <sys/queue.h>
38 #include <sys/event.h>
39 #include <signal.h>
40 #include <stdio.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44 #include <errno.h>
45 #ifdef _EVENT_HAVE_INTTYPES_H
46 #include <inttypes.h>
47 #endif
48
49 /* Some platforms apparently define the udata field of struct kevent as
50 * intptr_t, whereas others define it as void*. There doesn't seem to be an
51 * easy way to tell them apart via autoconf, so we need to use OS macros. */
52 #if defined(_EVENT_HAVE_INTTYPES_H) && !defined(__OpenBSD__) && !defined(__FreeBSD__) && !defined(__darwin__) && !defined(__APPLE__)
53 #define PTR_TO_UDATA(x) ((intptr_t)(x))
54 #define INT_TO_UDATA(x) ((intptr_t)(x))
55 #else
56 #define PTR_TO_UDATA(x) (x)
57 #define INT_TO_UDATA(x) ((void*)(x))
58 #endif
59
60 #include "event-internal.h"
61 #include "log-internal.h"
62 #include "evmap-internal.h"
63 #include "event2/thread.h"
64 #include "evthread-internal.h"
65 #include "changelist-internal.h"
66
67 #define NEVENT 64
68
69 struct kqop {
70 struct kevent *changes;
71 int changes_size;
72
73 struct kevent *events;
74 int events_size;
75 int kq;
76 pid_t pid;
77 };
78
79 static void kqop_free(struct kqop *kqop);
80
81 static void *kq_init(struct event_base *);
82 static int kq_sig_add(struct event_base *, int, short, short, void *);
83 static int kq_sig_del(struct event_base *, int, short, short, void *);
84 static int kq_dispatch(struct event_base *, struct timeval *);
85 static void kq_dealloc(struct event_base *);
86
87 const struct eventop kqops = {
88 "kqueue",
89 kq_init,
90 event_changelist_add,
91 event_changelist_del,
92 kq_dispatch,
93 kq_dealloc,
94 1 /* need reinit */,
95 EV_FEATURE_ET|EV_FEATURE_O1|EV_FEATURE_FDS,
96 EVENT_CHANGELIST_FDINFO_SIZE
97 };
98
99 static const struct eventop kqsigops = {
100 "kqueue_signal",
101 NULL,
102 kq_sig_add,
103 kq_sig_del,
104 NULL,
105 NULL,
106 1 /* need reinit */,
107 0,
108 0
109 };
110
111 static void *
kq_init(struct event_base * base)112 kq_init(struct event_base *base)
113 {
114 int kq = -1;
115 struct kqop *kqueueop = NULL;
116
117 if (!(kqueueop = mm_calloc(1, sizeof(struct kqop))))
118 return (NULL);
119
120 /* Initialize the kernel queue */
121
122 if ((kq = kqueue()) == -1) {
123 event_warn("kqueue");
124 goto err;
125 }
126
127 kqueueop->kq = kq;
128
129 kqueueop->pid = getpid();
130
131 /* Initialize fields */
132 kqueueop->changes = mm_calloc(NEVENT, sizeof(struct kevent));
133 if (kqueueop->changes == NULL)
134 goto err;
135 kqueueop->events = mm_calloc(NEVENT, sizeof(struct kevent));
136 if (kqueueop->events == NULL)
137 goto err;
138 kqueueop->events_size = kqueueop->changes_size = NEVENT;
139
140 /* Check for Mac OS X kqueue bug. */
141 memset(&kqueueop->changes[0], 0, sizeof kqueueop->changes[0]);
142 kqueueop->changes[0].ident = -1;
143 kqueueop->changes[0].filter = EVFILT_READ;
144 kqueueop->changes[0].flags = EV_ADD;
145 /*
146 * If kqueue works, then kevent will succeed, and it will
147 * stick an error in events[0]. If kqueue is broken, then
148 * kevent will fail.
149 */
150 if (kevent(kq,
151 kqueueop->changes, 1, kqueueop->events, NEVENT, NULL) != 1 ||
152 (int)kqueueop->events[0].ident != -1 ||
153 kqueueop->events[0].flags != EV_ERROR) {
154 event_warn("%s: detected broken kqueue; not using.", __func__);
155 goto err;
156 }
157
158 base->evsigsel = &kqsigops;
159
160 return (kqueueop);
161 err:
162 if (kqueueop)
163 kqop_free(kqueueop);
164
165 return (NULL);
166 }
167
168 static void
kq_sighandler(int sig)169 kq_sighandler(int sig)
170 {
171 /* Do nothing here */
172 }
173
174 #define ADD_UDATA 0x30303
175
176 static void
kq_setup_kevent(struct kevent * out,evutil_socket_t fd,int filter,short change)177 kq_setup_kevent(struct kevent *out, evutil_socket_t fd, int filter, short change)
178 {
179 memset(out, 0, sizeof(struct kevent));
180 out->ident = fd;
181 out->filter = filter;
182
183 if (change & EV_CHANGE_ADD) {
184 out->flags = EV_ADD;
185 /* We set a magic number here so that we can tell 'add'
186 * errors from 'del' errors. */
187 out->udata = INT_TO_UDATA(ADD_UDATA);
188 if (change & EV_ET)
189 out->flags |= EV_CLEAR;
190 #ifdef NOTE_EOF
191 /* Make it behave like select() and poll() */
192 if (filter == EVFILT_READ)
193 out->fflags = NOTE_EOF;
194 #endif
195 } else {
196 EVUTIL_ASSERT(change & EV_CHANGE_DEL);
197 out->flags = EV_DELETE;
198 }
199 }
200
201 static int
kq_build_changes_list(const struct event_changelist * changelist,struct kqop * kqop)202 kq_build_changes_list(const struct event_changelist *changelist,
203 struct kqop *kqop)
204 {
205 int i;
206 int n_changes = 0;
207
208 for (i = 0; i < changelist->n_changes; ++i) {
209 struct event_change *in_ch = &changelist->changes[i];
210 struct kevent *out_ch;
211 if (n_changes >= kqop->changes_size - 1) {
212 int newsize = kqop->changes_size * 2;
213 struct kevent *newchanges;
214
215 newchanges = mm_realloc(kqop->changes,
216 newsize * sizeof(struct kevent));
217 if (newchanges == NULL) {
218 event_warn("%s: realloc", __func__);
219 return (-1);
220 }
221 kqop->changes = newchanges;
222 kqop->changes_size = newsize;
223 }
224 if (in_ch->read_change) {
225 out_ch = &kqop->changes[n_changes++];
226 kq_setup_kevent(out_ch, in_ch->fd, EVFILT_READ,
227 in_ch->read_change);
228 }
229 if (in_ch->write_change) {
230 out_ch = &kqop->changes[n_changes++];
231 kq_setup_kevent(out_ch, in_ch->fd, EVFILT_WRITE,
232 in_ch->write_change);
233 }
234 }
235 return n_changes;
236 }
237
238 static int
kq_grow_events(struct kqop * kqop,size_t new_size)239 kq_grow_events(struct kqop *kqop, size_t new_size)
240 {
241 struct kevent *newresult;
242
243 newresult = mm_realloc(kqop->events,
244 new_size * sizeof(struct kevent));
245
246 if (newresult) {
247 kqop->events = newresult;
248 kqop->events_size = new_size;
249 return 0;
250 } else {
251 return -1;
252 }
253 }
254
255 static int
kq_dispatch(struct event_base * base,struct timeval * tv)256 kq_dispatch(struct event_base *base, struct timeval *tv)
257 {
258 struct kqop *kqop = base->evbase;
259 struct kevent *events = kqop->events;
260 struct kevent *changes;
261 struct timespec ts, *ts_p = NULL;
262 int i, n_changes, res;
263
264 if (tv != NULL) {
265 TIMEVAL_TO_TIMESPEC(tv, &ts);
266 ts_p = &ts;
267 }
268
269 /* Build "changes" from "base->changes" */
270 EVUTIL_ASSERT(kqop->changes);
271 n_changes = kq_build_changes_list(&base->changelist, kqop);
272 if (n_changes < 0)
273 return -1;
274
275 event_changelist_remove_all(&base->changelist, base);
276
277 /* steal the changes array in case some broken code tries to call
278 * dispatch twice at once. */
279 changes = kqop->changes;
280 kqop->changes = NULL;
281
282 /* Make sure that 'events' is at least as long as the list of changes:
283 * otherwise errors in the changes can get reported as a -1 return
284 * value from kevent() rather than as EV_ERROR events in the events
285 * array.
286 *
287 * (We could instead handle -1 return values from kevent() by
288 * retrying with a smaller changes array or a larger events array,
289 * but this approach seems less risky for now.)
290 */
291 if (kqop->events_size < n_changes) {
292 int new_size = kqop->events_size;
293 do {
294 new_size *= 2;
295 } while (new_size < n_changes);
296
297 kq_grow_events(kqop, new_size);
298 events = kqop->events;
299 }
300
301 EVBASE_RELEASE_LOCK(base, th_base_lock);
302
303 res = kevent(kqop->kq, changes, n_changes,
304 events, kqop->events_size, ts_p);
305
306 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
307
308 EVUTIL_ASSERT(kqop->changes == NULL);
309 kqop->changes = changes;
310
311 if (res == -1) {
312 if (errno != EINTR) {
313 event_warn("kevent");
314 return (-1);
315 }
316
317 return (0);
318 }
319
320 event_debug(("%s: kevent reports %d", __func__, res));
321
322 for (i = 0; i < res; i++) {
323 int which = 0;
324
325 if (events[i].flags & EV_ERROR) {
326 switch (events[i].data) {
327
328 /* Can occur on delete if we are not currently
329 * watching any events on this fd. That can
330 * happen when the fd was closed and another
331 * file was opened with that fd. */
332 case ENOENT:
333 /* Can occur for reasons not fully understood
334 * on FreeBSD. */
335 case EINVAL:
336 continue;
337
338 /* Can occur on a delete if the fd is closed. */
339 case EBADF:
340 /* XXXX On NetBSD, we can also get EBADF if we
341 * try to add the write side of a pipe, but
342 * the read side has already been closed.
343 * Other BSDs call this situation 'EPIPE'. It
344 * would be good if we had a way to report
345 * this situation. */
346 continue;
347 /* These two can occur on an add if the fd was one side
348 * of a pipe, and the other side was closed. */
349 case EPERM:
350 case EPIPE:
351 /* Report read events, if we're listening for
352 * them, so that the user can learn about any
353 * add errors. (If the operation was a
354 * delete, then udata should be cleared.) */
355 if (events[i].udata) {
356 /* The operation was an add:
357 * report the error as a read. */
358 which |= EV_READ;
359 break;
360 } else {
361 /* The operation was a del:
362 * report nothing. */
363 continue;
364 }
365
366 /* Other errors shouldn't occur. */
367 default:
368 errno = events[i].data;
369 return (-1);
370 }
371 } else if (events[i].filter == EVFILT_READ) {
372 which |= EV_READ;
373 } else if (events[i].filter == EVFILT_WRITE) {
374 which |= EV_WRITE;
375 } else if (events[i].filter == EVFILT_SIGNAL) {
376 which |= EV_SIGNAL;
377 }
378
379 if (!which)
380 continue;
381
382 if (events[i].filter == EVFILT_SIGNAL) {
383 evmap_signal_active(base, events[i].ident, 1);
384 } else {
385 evmap_io_active(base, events[i].ident, which | EV_ET);
386 }
387 }
388
389 if (res == kqop->events_size) {
390 /* We used all the events space that we have. Maybe we should
391 make it bigger. */
392 kq_grow_events(kqop, kqop->events_size * 2);
393 }
394
395 return (0);
396 }
397
398 static void
kqop_free(struct kqop * kqop)399 kqop_free(struct kqop *kqop)
400 {
401 if (kqop->changes)
402 mm_free(kqop->changes);
403 if (kqop->events)
404 mm_free(kqop->events);
405 if (kqop->kq >= 0 && kqop->pid == getpid())
406 close(kqop->kq);
407 memset(kqop, 0, sizeof(struct kqop));
408 mm_free(kqop);
409 }
410
411 static void
kq_dealloc(struct event_base * base)412 kq_dealloc(struct event_base *base)
413 {
414 struct kqop *kqop = base->evbase;
415 evsig_dealloc(base);
416 kqop_free(kqop);
417 }
418
419 /* signal handling */
420 static int
kq_sig_add(struct event_base * base,int nsignal,short old,short events,void * p)421 kq_sig_add(struct event_base *base, int nsignal, short old, short events, void *p)
422 {
423 struct kqop *kqop = base->evbase;
424 struct kevent kev;
425 struct timespec timeout = { 0, 0 };
426 (void)p;
427
428 EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
429
430 memset(&kev, 0, sizeof(kev));
431 kev.ident = nsignal;
432 kev.filter = EVFILT_SIGNAL;
433 kev.flags = EV_ADD;
434
435 /* Be ready for the signal if it is sent any
436 * time between now and the next call to
437 * kq_dispatch. */
438 if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
439 return (-1);
440
441 /* XXXX The manpage suggest we could use SIG_IGN instead of a
442 * do-nothing handler */
443 if (_evsig_set_handler(base, nsignal, kq_sighandler) == -1)
444 return (-1);
445
446 return (0);
447 }
448
449 static int
kq_sig_del(struct event_base * base,int nsignal,short old,short events,void * p)450 kq_sig_del(struct event_base *base, int nsignal, short old, short events, void *p)
451 {
452 struct kqop *kqop = base->evbase;
453 struct kevent kev;
454
455 struct timespec timeout = { 0, 0 };
456 (void)p;
457
458 EVUTIL_ASSERT(nsignal >= 0 && nsignal < NSIG);
459
460 memset(&kev, 0, sizeof(kev));
461 kev.ident = nsignal;
462 kev.filter = EVFILT_SIGNAL;
463 kev.flags = EV_DELETE;
464
465 /* Because we insert signal events
466 * immediately, we need to delete them
467 * immediately, too */
468 if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1)
469 return (-1);
470
471 if (_evsig_restore_handler(base, nsignal) == -1)
472 return (-1);
473
474 return (0);
475 }
476