1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2011 NetApp, Inc.
5 * All rights reserved.
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 *
16 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 /*
30 * Micro event library for FreeBSD, designed for a single i/o thread
31 * using kqueue, and having events be persistent by default.
32 */
33
34 #include <sys/cdefs.h>
35 #include <assert.h>
36 #ifndef WITHOUT_CAPSICUM
37 #include <capsicum_helpers.h>
38 #endif
39 #include <err.h>
40 #include <errno.h>
41 #include <stdbool.h>
42 #include <stdlib.h>
43 #include <stdio.h>
44 #include <string.h>
45 #include <sysexits.h>
46 #include <unistd.h>
47
48 #include <sys/types.h>
49 #ifndef WITHOUT_CAPSICUM
50 #include <sys/capsicum.h>
51 #endif
52 #include <sys/event.h>
53 #include <sys/time.h>
54
55 #include <pthread.h>
56 #include <pthread_np.h>
57
58 #include "mevent.h"
59
60 #define MEVENT_MAX 64
61
62 static pthread_t mevent_tid;
63 static pthread_once_t mevent_once = PTHREAD_ONCE_INIT;
64 static int mevent_timid = 43;
65 static int mevent_pipefd[2];
66 static int mfd;
67 static pthread_mutex_t mevent_lmutex = PTHREAD_MUTEX_INITIALIZER;
68
69 struct mevent {
70 void (*me_func)(int, enum ev_type, void *);
71 #define me_msecs me_fd
72 int me_fd;
73 int me_timid;
74 enum ev_type me_type;
75 void *me_param;
76 int me_cq;
77 int me_state; /* Desired kevent flags. */
78 int me_closefd;
79 int me_fflags;
80 LIST_ENTRY(mevent) me_list;
81 };
82
83 enum mevent_update_type {
84 UPDATE_ENABLE,
85 UPDATE_DISABLE,
86 UPDATE_TIMER,
87 };
88
LIST_HEAD(listhead,mevent)89 static LIST_HEAD(listhead, mevent) global_head, change_head;
90
91 static void
92 mevent_qlock(void)
93 {
94 pthread_mutex_lock(&mevent_lmutex);
95 }
96
97 static void
mevent_qunlock(void)98 mevent_qunlock(void)
99 {
100 pthread_mutex_unlock(&mevent_lmutex);
101 }
102
103 static void
mevent_pipe_read(int fd,enum ev_type type __unused,void * param __unused)104 mevent_pipe_read(int fd, enum ev_type type __unused, void *param __unused)
105 {
106 char buf[MEVENT_MAX];
107 int status;
108
109 /*
110 * Drain the pipe read side. The fd is non-blocking so this is
111 * safe to do.
112 */
113 do {
114 status = read(fd, buf, sizeof(buf));
115 } while (status == MEVENT_MAX);
116 }
117
118 static void
mevent_notify(void)119 mevent_notify(void)
120 {
121 char c = '\0';
122
123 /*
124 * If calling from outside the i/o thread, write a byte on the
125 * pipe to force the i/o thread to exit the blocking kevent call.
126 */
127 if (mevent_pipefd[1] != 0 && pthread_self() != mevent_tid) {
128 write(mevent_pipefd[1], &c, 1);
129 }
130 }
131
132 static void
mevent_init(void)133 mevent_init(void)
134 {
135 #ifndef WITHOUT_CAPSICUM
136 cap_rights_t rights;
137 #endif
138
139 mfd = kqueue();
140 assert(mfd > 0);
141
142 #ifndef WITHOUT_CAPSICUM
143 cap_rights_init(&rights, CAP_KQUEUE);
144 if (caph_rights_limit(mfd, &rights) == -1)
145 errx(EX_OSERR, "Unable to apply rights for sandbox");
146 #endif
147
148 LIST_INIT(&change_head);
149 LIST_INIT(&global_head);
150 }
151
152 static int
mevent_kq_filter(struct mevent * mevp)153 mevent_kq_filter(struct mevent *mevp)
154 {
155 int retval;
156
157 retval = 0;
158
159 if (mevp->me_type == EVF_READ)
160 retval = EVFILT_READ;
161
162 if (mevp->me_type == EVF_WRITE)
163 retval = EVFILT_WRITE;
164
165 if (mevp->me_type == EVF_TIMER)
166 retval = EVFILT_TIMER;
167
168 if (mevp->me_type == EVF_SIGNAL)
169 retval = EVFILT_SIGNAL;
170
171 if (mevp->me_type == EVF_VNODE)
172 retval = EVFILT_VNODE;
173
174 return (retval);
175 }
176
177 static int
mevent_kq_flags(struct mevent * mevp)178 mevent_kq_flags(struct mevent *mevp)
179 {
180 int retval;
181
182 retval = mevp->me_state;
183
184 if (mevp->me_type == EVF_VNODE)
185 retval |= EV_CLEAR;
186
187 return (retval);
188 }
189
190 static int
mevent_kq_fflags(struct mevent * mevp)191 mevent_kq_fflags(struct mevent *mevp)
192 {
193 int retval;
194
195 retval = 0;
196
197 switch (mevp->me_type) {
198 case EVF_VNODE:
199 if ((mevp->me_fflags & EVFF_ATTRIB) != 0)
200 retval |= NOTE_ATTRIB;
201 break;
202 case EVF_READ:
203 case EVF_WRITE:
204 case EVF_TIMER:
205 case EVF_SIGNAL:
206 break;
207 }
208
209 return (retval);
210 }
211
212 static void
mevent_populate(struct mevent * mevp,struct kevent * kev)213 mevent_populate(struct mevent *mevp, struct kevent *kev)
214 {
215 if (mevp->me_type == EVF_TIMER) {
216 kev->ident = mevp->me_timid;
217 kev->data = mevp->me_msecs;
218 } else {
219 kev->ident = mevp->me_fd;
220 kev->data = 0;
221 }
222 kev->filter = mevent_kq_filter(mevp);
223 kev->flags = mevent_kq_flags(mevp);
224 kev->fflags = mevent_kq_fflags(mevp);
225 kev->udata = mevp;
226 }
227
228 static int
mevent_build(struct kevent * kev)229 mevent_build(struct kevent *kev)
230 {
231 struct mevent *mevp, *tmpp;
232 int i;
233
234 i = 0;
235
236 mevent_qlock();
237
238 LIST_FOREACH_SAFE(mevp, &change_head, me_list, tmpp) {
239 if (mevp->me_closefd) {
240 /*
241 * A close of the file descriptor will remove the
242 * event
243 */
244 close(mevp->me_fd);
245 } else {
246 mevent_populate(mevp, &kev[i]);
247 i++;
248 }
249
250 mevp->me_cq = 0;
251 LIST_REMOVE(mevp, me_list);
252
253 if (mevp->me_state & EV_DELETE) {
254 free(mevp);
255 } else {
256 LIST_INSERT_HEAD(&global_head, mevp, me_list);
257 }
258
259 assert(i < MEVENT_MAX);
260 }
261
262 mevent_qunlock();
263
264 return (i);
265 }
266
267 static void
mevent_handle(struct kevent * kev,int numev)268 mevent_handle(struct kevent *kev, int numev)
269 {
270 struct mevent *mevp;
271 int i;
272
273 for (i = 0; i < numev; i++) {
274 mevp = kev[i].udata;
275
276 /* XXX check for EV_ERROR ? */
277
278 (*mevp->me_func)(mevp->me_fd, mevp->me_type, mevp->me_param);
279 }
280 }
281
282 static struct mevent *
mevent_add_state(int tfd,enum ev_type type,void (* func)(int,enum ev_type,void *),void * param,int state,int fflags)283 mevent_add_state(int tfd, enum ev_type type,
284 void (*func)(int, enum ev_type, void *), void *param,
285 int state, int fflags)
286 {
287 struct kevent kev;
288 struct mevent *lp, *mevp;
289 int ret;
290
291 if (tfd < 0 || func == NULL) {
292 return (NULL);
293 }
294
295 mevp = NULL;
296
297 pthread_once(&mevent_once, mevent_init);
298
299 mevent_qlock();
300
301 /*
302 * Verify that the fd/type tuple is not present in any list
303 */
304 LIST_FOREACH(lp, &global_head, me_list) {
305 if (type != EVF_TIMER && lp->me_fd == tfd &&
306 lp->me_type == type) {
307 goto exit;
308 }
309 }
310
311 LIST_FOREACH(lp, &change_head, me_list) {
312 if (type != EVF_TIMER && lp->me_fd == tfd &&
313 lp->me_type == type) {
314 goto exit;
315 }
316 }
317
318 /*
319 * Allocate an entry and populate it.
320 */
321 mevp = calloc(1, sizeof(struct mevent));
322 if (mevp == NULL) {
323 goto exit;
324 }
325
326 if (type == EVF_TIMER) {
327 mevp->me_msecs = tfd;
328 mevp->me_timid = mevent_timid++;
329 } else
330 mevp->me_fd = tfd;
331 mevp->me_type = type;
332 mevp->me_func = func;
333 mevp->me_param = param;
334 mevp->me_state = state;
335 mevp->me_fflags = fflags;
336
337 /*
338 * Try to add the event. If this fails, report the failure to
339 * the caller.
340 */
341 mevent_populate(mevp, &kev);
342 ret = kevent(mfd, &kev, 1, NULL, 0, NULL);
343 if (ret == -1) {
344 free(mevp);
345 mevp = NULL;
346 goto exit;
347 }
348
349 mevp->me_state &= ~EV_ADD;
350 LIST_INSERT_HEAD(&global_head, mevp, me_list);
351
352 exit:
353 mevent_qunlock();
354
355 return (mevp);
356 }
357
358 struct mevent *
mevent_add(int tfd,enum ev_type type,void (* func)(int,enum ev_type,void *),void * param)359 mevent_add(int tfd, enum ev_type type,
360 void (*func)(int, enum ev_type, void *), void *param)
361 {
362
363 return (mevent_add_state(tfd, type, func, param, EV_ADD, 0));
364 }
365
366 struct mevent *
mevent_add_flags(int tfd,enum ev_type type,int fflags,void (* func)(int,enum ev_type,void *),void * param)367 mevent_add_flags(int tfd, enum ev_type type, int fflags,
368 void (*func)(int, enum ev_type, void *), void *param)
369 {
370
371 return (mevent_add_state(tfd, type, func, param, EV_ADD, fflags));
372 }
373
374 struct mevent *
mevent_add_disabled(int tfd,enum ev_type type,void (* func)(int,enum ev_type,void *),void * param)375 mevent_add_disabled(int tfd, enum ev_type type,
376 void (*func)(int, enum ev_type, void *), void *param)
377 {
378
379 return (mevent_add_state(tfd, type, func, param, EV_ADD | EV_DISABLE, 0));
380 }
381
382 static int
mevent_update(struct mevent * evp,enum mevent_update_type type,int msecs)383 mevent_update(struct mevent *evp, enum mevent_update_type type, int msecs)
384 {
385 int newstate;
386
387 mevent_qlock();
388
389 /*
390 * It's not possible to update a deleted event
391 */
392 assert((evp->me_state & EV_DELETE) == 0);
393
394 newstate = evp->me_state;
395 if (type == UPDATE_ENABLE) {
396 newstate |= EV_ENABLE;
397 newstate &= ~EV_DISABLE;
398 } else if (type == UPDATE_DISABLE) {
399 newstate |= EV_DISABLE;
400 newstate &= ~EV_ENABLE;
401 } else {
402 assert(type == UPDATE_TIMER);
403 assert(evp->me_type == EVF_TIMER);
404 newstate |= EV_ADD;
405 evp->me_msecs = msecs;
406 }
407
408 /*
409 * No update needed if enable/disable had no effect
410 */
411 if (evp->me_state != newstate || type == UPDATE_TIMER) {
412 evp->me_state = newstate;
413
414 /*
415 * Place the entry onto the changed list if not
416 * already there.
417 */
418 if (evp->me_cq == 0) {
419 evp->me_cq = 1;
420 LIST_REMOVE(evp, me_list);
421 LIST_INSERT_HEAD(&change_head, evp, me_list);
422 mevent_notify();
423 }
424 }
425
426 mevent_qunlock();
427
428 return (0);
429 }
430
431 int
mevent_enable(struct mevent * evp)432 mevent_enable(struct mevent *evp)
433 {
434 return (mevent_update(evp, UPDATE_ENABLE, -1));
435 }
436
437 int
mevent_disable(struct mevent * evp)438 mevent_disable(struct mevent *evp)
439 {
440 return (mevent_update(evp, UPDATE_DISABLE, -1));
441 }
442
443 int
mevent_timer_update(struct mevent * evp,int msecs)444 mevent_timer_update(struct mevent *evp, int msecs)
445 {
446 return (mevent_update(evp, UPDATE_TIMER, msecs));
447 }
448
449 static int
mevent_delete_event(struct mevent * evp,int closefd)450 mevent_delete_event(struct mevent *evp, int closefd)
451 {
452 mevent_qlock();
453
454 /*
455 * Place the entry onto the changed list if not already there, and
456 * mark as to be deleted.
457 */
458 if (evp->me_cq == 0) {
459 evp->me_cq = 1;
460 LIST_REMOVE(evp, me_list);
461 LIST_INSERT_HEAD(&change_head, evp, me_list);
462 mevent_notify();
463 }
464 evp->me_state = EV_DELETE;
465
466 if (closefd)
467 evp->me_closefd = 1;
468
469 mevent_qunlock();
470
471 return (0);
472 }
473
474 int
mevent_delete(struct mevent * evp)475 mevent_delete(struct mevent *evp)
476 {
477
478 return (mevent_delete_event(evp, 0));
479 }
480
481 int
mevent_delete_close(struct mevent * evp)482 mevent_delete_close(struct mevent *evp)
483 {
484
485 return (mevent_delete_event(evp, 1));
486 }
487
488 static void
mevent_set_name(void)489 mevent_set_name(void)
490 {
491
492 pthread_set_name_np(mevent_tid, "mevent");
493 }
494
495 void
mevent_dispatch(void)496 mevent_dispatch(void)
497 {
498 struct kevent changelist[MEVENT_MAX];
499 struct kevent eventlist[MEVENT_MAX];
500 struct mevent *pipev;
501 int numev;
502 int ret;
503 #ifndef WITHOUT_CAPSICUM
504 cap_rights_t rights;
505 #endif
506
507 mevent_tid = pthread_self();
508 mevent_set_name();
509
510 pthread_once(&mevent_once, mevent_init);
511
512 /*
513 * Open the pipe that will be used for other threads to force
514 * the blocking kqueue call to exit by writing to it. Set the
515 * descriptor to non-blocking.
516 */
517 ret = pipe(mevent_pipefd);
518 if (ret < 0) {
519 perror("pipe");
520 exit(0);
521 }
522
523 #ifndef WITHOUT_CAPSICUM
524 cap_rights_init(&rights, CAP_EVENT, CAP_READ, CAP_WRITE);
525 if (caph_rights_limit(mevent_pipefd[0], &rights) == -1)
526 errx(EX_OSERR, "Unable to apply rights for sandbox");
527 if (caph_rights_limit(mevent_pipefd[1], &rights) == -1)
528 errx(EX_OSERR, "Unable to apply rights for sandbox");
529 #endif
530
531 /*
532 * Add internal event handler for the pipe write fd
533 */
534 pipev = mevent_add(mevent_pipefd[0], EVF_READ, mevent_pipe_read, NULL);
535 assert(pipev != NULL);
536
537 for (;;) {
538 /*
539 * Build changelist if required.
540 * XXX the changelist can be put into the blocking call
541 * to eliminate the extra syscall. Currently better for
542 * debug.
543 */
544 numev = mevent_build(changelist);
545 if (numev) {
546 ret = kevent(mfd, changelist, numev, NULL, 0, NULL);
547 if (ret == -1) {
548 perror("Error return from kevent change");
549 }
550 }
551
552 /*
553 * Block awaiting events
554 */
555 ret = kevent(mfd, NULL, 0, eventlist, MEVENT_MAX, NULL);
556 if (ret == -1 && errno != EINTR) {
557 perror("Error return from kevent monitor");
558 }
559
560 /*
561 * Handle reported events
562 */
563 mevent_handle(eventlist, ret);
564 }
565 }
566