1 /* $NetBSD: devpoll.c,v 1.5 2020/05/25 20:47:33 christos Exp $ */
2
3 /*
4 * Copyright 2000-2009 Niels Provos <provos@citi.umich.edu>
5 * Copyright 2009-2012 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 #include "evconfig-private.h"
31
32 #ifdef EVENT__HAVE_DEVPOLL
33
34 #include <sys/types.h>
35 #include <sys/resource.h>
36 #ifdef EVENT__HAVE_SYS_TIME_H
37 #include <sys/time.h>
38 #endif
39 #include <sys/queue.h>
40 #include <sys/devpoll.h>
41 #include <signal.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <unistd.h>
46 #include <fcntl.h>
47 #include <errno.h>
48
49 #include "event2/event.h"
50 #include "event2/event_struct.h"
51 #include "event2/thread.h"
52 #include "event-internal.h"
53 #include "evsignal-internal.h"
54 #include "log-internal.h"
55 #include "evmap-internal.h"
56 #include "evthread-internal.h"
57
58 struct devpollop {
59 struct pollfd *events;
60 int nevents;
61 int dpfd;
62 struct pollfd *changes;
63 int nchanges;
64 };
65
66 static void *devpoll_init(struct event_base *);
67 static int devpoll_add(struct event_base *, int fd, short old, short events, void *);
68 static int devpoll_del(struct event_base *, int fd, short old, short events, void *);
69 static int devpoll_dispatch(struct event_base *, struct timeval *);
70 static void devpoll_dealloc(struct event_base *);
71
72 const struct eventop devpollops = {
73 "devpoll",
74 devpoll_init,
75 devpoll_add,
76 devpoll_del,
77 devpoll_dispatch,
78 devpoll_dealloc,
79 1, /* need reinit */
80 EV_FEATURE_FDS|EV_FEATURE_O1,
81 0
82 };
83
84 #define NEVENT 32000
85
86 static int
devpoll_commit(struct devpollop * devpollop)87 devpoll_commit(struct devpollop *devpollop)
88 {
89 /*
90 * Due to a bug in Solaris, we have to use pwrite with an offset of 0.
91 * Write is limited to 2GB of data, until it will fail.
92 */
93 if (pwrite(devpollop->dpfd, devpollop->changes,
94 sizeof(struct pollfd) * devpollop->nchanges, 0) == -1)
95 return (-1);
96
97 devpollop->nchanges = 0;
98 return (0);
99 }
100
101 static int
devpoll_queue(struct devpollop * devpollop,int fd,int events)102 devpoll_queue(struct devpollop *devpollop, int fd, int events) {
103 struct pollfd *pfd;
104
105 if (devpollop->nchanges >= devpollop->nevents) {
106 /*
107 * Change buffer is full, must commit it to /dev/poll before
108 * adding more
109 */
110 if (devpoll_commit(devpollop) != 0)
111 return (-1);
112 }
113
114 pfd = &devpollop->changes[devpollop->nchanges++];
115 pfd->fd = fd;
116 pfd->events = events;
117 pfd->revents = 0;
118
119 return (0);
120 }
121
122 static void *
devpoll_init(struct event_base * base)123 devpoll_init(struct event_base *base)
124 {
125 int dpfd, nfiles = NEVENT;
126 struct rlimit rl;
127 struct devpollop *devpollop;
128
129 if (!(devpollop = mm_calloc(1, sizeof(struct devpollop))))
130 return (NULL);
131
132 if (getrlimit(RLIMIT_NOFILE, &rl) == 0 &&
133 rl.rlim_cur != RLIM_INFINITY)
134 nfiles = rl.rlim_cur;
135
136 /* Initialize the kernel queue */
137 if ((dpfd = evutil_open_closeonexec_("/dev/poll", O_RDWR, 0)) == -1) {
138 event_warn("open: /dev/poll");
139 mm_free(devpollop);
140 return (NULL);
141 }
142
143 devpollop->dpfd = dpfd;
144
145 /* Initialize fields */
146 /* FIXME: allocating 'nfiles' worth of space here can be
147 * expensive and unnecessary. See how epoll.c does it instead. */
148 devpollop->events = mm_calloc(nfiles, sizeof(struct pollfd));
149 if (devpollop->events == NULL) {
150 mm_free(devpollop);
151 close(dpfd);
152 return (NULL);
153 }
154 devpollop->nevents = nfiles;
155
156 devpollop->changes = mm_calloc(nfiles, sizeof(struct pollfd));
157 if (devpollop->changes == NULL) {
158 mm_free(devpollop->events);
159 mm_free(devpollop);
160 close(dpfd);
161 return (NULL);
162 }
163
164 evsig_init_(base);
165
166 return (devpollop);
167 }
168
169 static int
devpoll_dispatch(struct event_base * base,struct timeval * tv)170 devpoll_dispatch(struct event_base *base, struct timeval *tv)
171 {
172 struct devpollop *devpollop = base->evbase;
173 struct pollfd *events = devpollop->events;
174 struct dvpoll dvp;
175 int i, res, timeout = -1;
176
177 if (devpollop->nchanges)
178 devpoll_commit(devpollop);
179
180 if (tv != NULL)
181 timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
182
183 dvp.dp_fds = devpollop->events;
184 dvp.dp_nfds = devpollop->nevents;
185 dvp.dp_timeout = timeout;
186
187 EVBASE_RELEASE_LOCK(base, th_base_lock);
188
189 res = ioctl(devpollop->dpfd, DP_POLL, &dvp);
190
191 EVBASE_ACQUIRE_LOCK(base, th_base_lock);
192
193 if (res == -1) {
194 if (errno != EINTR) {
195 event_warn("ioctl: DP_POLL");
196 return (-1);
197 }
198
199 return (0);
200 }
201
202 event_debug(("%s: devpoll_wait reports %d", __func__, res));
203
204 for (i = 0; i < res; i++) {
205 int which = 0;
206 int what = events[i].revents;
207
208 if (what & POLLHUP)
209 what |= POLLIN | POLLOUT;
210 else if (what & POLLERR)
211 what |= POLLIN | POLLOUT;
212
213 if (what & POLLIN)
214 which |= EV_READ;
215 if (what & POLLOUT)
216 which |= EV_WRITE;
217
218 if (!which)
219 continue;
220
221 /* XXX(niels): not sure if this works for devpoll */
222 evmap_io_active_(base, events[i].fd, which);
223 }
224
225 return (0);
226 }
227
228
229 static int
devpoll_add(struct event_base * base,int fd,short old,short events,void * p)230 devpoll_add(struct event_base *base, int fd, short old, short events, void *p)
231 {
232 struct devpollop *devpollop = base->evbase;
233 int res;
234 (void)p;
235
236 /*
237 * It's not necessary to OR the existing read/write events that we
238 * are currently interested in with the new event we are adding.
239 * The /dev/poll driver ORs any new events with the existing events
240 * that it has cached for the fd.
241 */
242
243 res = 0;
244 if (events & EV_READ)
245 res |= POLLIN;
246 if (events & EV_WRITE)
247 res |= POLLOUT;
248
249 if (devpoll_queue(devpollop, fd, res) != 0)
250 return (-1);
251
252 return (0);
253 }
254
255 static int
devpoll_del(struct event_base * base,int fd,short old,short events,void * p)256 devpoll_del(struct event_base *base, int fd, short old, short events, void *p)
257 {
258 struct devpollop *devpollop = base->evbase;
259 int res;
260 (void)p;
261
262 res = 0;
263 if (events & EV_READ)
264 res |= POLLIN;
265 if (events & EV_WRITE)
266 res |= POLLOUT;
267
268 /*
269 * The only way to remove an fd from the /dev/poll monitored set is
270 * to use POLLREMOVE by itself. This removes ALL events for the fd
271 * provided so if we care about two events and are only removing one
272 * we must re-add the other event after POLLREMOVE.
273 */
274
275 if (devpoll_queue(devpollop, fd, POLLREMOVE) != 0)
276 return (-1);
277
278 if ((res & (POLLIN|POLLOUT)) != (POLLIN|POLLOUT)) {
279 /*
280 * We're not deleting all events, so we must resubmit the
281 * event that we are still interested in if one exists.
282 */
283
284 if ((res & POLLIN) && (old & EV_WRITE)) {
285 /* Deleting read, still care about write */
286 devpoll_queue(devpollop, fd, POLLOUT);
287 } else if ((res & POLLOUT) && (old & EV_READ)) {
288 /* Deleting write, still care about read */
289 devpoll_queue(devpollop, fd, POLLIN);
290 }
291 }
292
293 return (0);
294 }
295
296 static void
devpoll_dealloc(struct event_base * base)297 devpoll_dealloc(struct event_base *base)
298 {
299 struct devpollop *devpollop = base->evbase;
300
301 evsig_dealloc_(base);
302 if (devpollop->events)
303 mm_free(devpollop->events);
304 if (devpollop->changes)
305 mm_free(devpollop->changes);
306 if (devpollop->dpfd >= 0)
307 close(devpollop->dpfd);
308
309 memset(devpollop, 0, sizeof(struct devpollop));
310 mm_free(devpollop);
311 }
312
313 #endif /* EVENT__HAVE_DEVPOLL */
314