1 /* $OpenBSD: select.c,v 1.25 2016/09/03 11:31:17 nayden Exp $ */
2
3 /*
4 * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
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 * 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
30 #include <sys/types.h>
31 #include <sys/time.h>
32 #include <sys/select.h>
33 #include <sys/queue.h>
34
35 #include <signal.h>
36 #include <stdio.h>
37 #include <stdlib.h>
38 #include <string.h>
39 #include <unistd.h>
40 #include <errno.h>
41 #ifdef CHECK_INVARIANTS
42 #include <assert.h>
43 #endif
44
45 #include "event.h"
46 #include "event-internal.h"
47 #include "evsignal.h"
48 #include "log.h"
49
50 struct selectop {
51 int event_fds; /* Highest fd in fd set */
52 size_t event_fdsz;
53 fd_set *event_readset_in;
54 fd_set *event_writeset_in;
55 fd_set *event_readset_out;
56 fd_set *event_writeset_out;
57 struct event **event_r_by_fd;
58 struct event **event_w_by_fd;
59 };
60
61 static void *select_init (struct event_base *);
62 static int select_add (void *, struct event *);
63 static int select_del (void *, struct event *);
64 static int select_dispatch (struct event_base *, void *, struct timeval *);
65 static void select_dealloc (struct event_base *, void *);
66
67 const struct eventop selectops = {
68 "select",
69 select_init,
70 select_add,
71 select_del,
72 select_dispatch,
73 select_dealloc,
74 0
75 };
76
77 static int select_resize(struct selectop *sop, size_t fdsz);
78
79 static void *
select_init(struct event_base * base)80 select_init(struct event_base *base)
81 {
82 struct selectop *sop;
83
84 /* Disable select when this environment variable is set */
85 if (!issetugid() && getenv("EVENT_NOSELECT"))
86 return (NULL);
87
88 if (!(sop = calloc(1, sizeof(struct selectop))))
89 return (NULL);
90
91 select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
92
93 evsignal_init(base);
94
95 return (sop);
96 }
97
98 #ifdef CHECK_INVARIANTS
99 static void
check_selectop(struct selectop * sop)100 check_selectop(struct selectop *sop)
101 {
102 int i;
103 for (i = 0; i <= sop->event_fds; ++i) {
104 if (FD_ISSET(i, sop->event_readset_in)) {
105 assert(sop->event_r_by_fd[i]);
106 assert(sop->event_r_by_fd[i]->ev_events & EV_READ);
107 assert(sop->event_r_by_fd[i]->ev_fd == i);
108 } else {
109 assert(! sop->event_r_by_fd[i]);
110 }
111 if (FD_ISSET(i, sop->event_writeset_in)) {
112 assert(sop->event_w_by_fd[i]);
113 assert(sop->event_w_by_fd[i]->ev_events & EV_WRITE);
114 assert(sop->event_w_by_fd[i]->ev_fd == i);
115 } else {
116 assert(! sop->event_w_by_fd[i]);
117 }
118 }
119
120 }
121 #else
122 #define check_selectop(sop) do { (void) sop; } while (0)
123 #endif
124
125 static int
select_dispatch(struct event_base * base,void * arg,struct timeval * tv)126 select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
127 {
128 int res, i, j;
129 struct selectop *sop = arg;
130
131 check_selectop(sop);
132
133 memcpy(sop->event_readset_out, sop->event_readset_in,
134 sop->event_fdsz);
135 memcpy(sop->event_writeset_out, sop->event_writeset_in,
136 sop->event_fdsz);
137
138 res = select(sop->event_fds + 1, sop->event_readset_out,
139 sop->event_writeset_out, NULL, tv);
140
141 check_selectop(sop);
142
143 if (res == -1) {
144 if (errno != EINTR) {
145 event_warn("select");
146 return (-1);
147 }
148
149 evsignal_process(base);
150 return (0);
151 } else if (base->sig.evsignal_caught) {
152 evsignal_process(base);
153 }
154
155 event_debug(("%s: select reports %d", __func__, res));
156
157 check_selectop(sop);
158 i = arc4random_uniform(sop->event_fds + 1);
159 for (j = 0; j <= sop->event_fds; ++j) {
160 struct event *r_ev = NULL, *w_ev = NULL;
161 if (++i >= sop->event_fds+1)
162 i = 0;
163
164 res = 0;
165 if (FD_ISSET(i, sop->event_readset_out)) {
166 r_ev = sop->event_r_by_fd[i];
167 res |= EV_READ;
168 }
169 if (FD_ISSET(i, sop->event_writeset_out)) {
170 w_ev = sop->event_w_by_fd[i];
171 res |= EV_WRITE;
172 }
173 if (r_ev && (res & r_ev->ev_events)) {
174 event_active(r_ev, res & r_ev->ev_events, 1);
175 }
176 if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
177 event_active(w_ev, res & w_ev->ev_events, 1);
178 }
179 }
180 check_selectop(sop);
181
182 return (0);
183 }
184
185
186 static int
select_resize(struct selectop * sop,size_t fdsz)187 select_resize(struct selectop *sop, size_t fdsz)
188 {
189 size_t n_events, n_events_old;
190
191 fd_set *readset_in = NULL;
192 fd_set *writeset_in = NULL;
193 fd_set *readset_out = NULL;
194 fd_set *writeset_out = NULL;
195 struct event **r_by_fd = NULL;
196 struct event **w_by_fd = NULL;
197
198 n_events = (fdsz/sizeof(fd_mask)) * NFDBITS;
199 n_events_old = (sop->event_fdsz/sizeof(fd_mask)) * NFDBITS;
200
201 if (sop->event_readset_in)
202 check_selectop(sop);
203
204 if ((readset_in = realloc(sop->event_readset_in, fdsz)) == NULL)
205 goto error;
206 sop->event_readset_in = readset_in;
207 if ((readset_out = realloc(sop->event_readset_out, fdsz)) == NULL)
208 goto error;
209 sop->event_readset_out = readset_out;
210 if ((writeset_in = realloc(sop->event_writeset_in, fdsz)) == NULL)
211 goto error;
212 sop->event_writeset_in = writeset_in;
213 if ((writeset_out = realloc(sop->event_writeset_out, fdsz)) == NULL)
214 goto error;
215 sop->event_writeset_out = writeset_out;
216 if ((r_by_fd = reallocarray(sop->event_r_by_fd, n_events,
217 sizeof(struct event *))) == NULL)
218 goto error;
219 sop->event_r_by_fd = r_by_fd;
220 if ((w_by_fd = reallocarray(sop->event_w_by_fd, n_events,
221 sizeof(struct event *))) == NULL)
222 goto error;
223 sop->event_w_by_fd = w_by_fd;
224
225 memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
226 fdsz - sop->event_fdsz);
227 memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
228 fdsz - sop->event_fdsz);
229 memset(sop->event_r_by_fd + n_events_old, 0,
230 (n_events-n_events_old) * sizeof(struct event*));
231 memset(sop->event_w_by_fd + n_events_old, 0,
232 (n_events-n_events_old) * sizeof(struct event*));
233
234 sop->event_fdsz = fdsz;
235 check_selectop(sop);
236
237 return (0);
238
239 error:
240 event_warn("malloc");
241 return (-1);
242 }
243
244
245 static int
select_add(void * arg,struct event * ev)246 select_add(void *arg, struct event *ev)
247 {
248 struct selectop *sop = arg;
249
250 if (ev->ev_events & EV_SIGNAL)
251 return (evsignal_add(ev));
252
253 check_selectop(sop);
254 /*
255 * Keep track of the highest fd, so that we can calculate the size
256 * of the fd_sets for select(2)
257 */
258 if (sop->event_fds < ev->ev_fd) {
259 size_t fdsz = sop->event_fdsz;
260
261 if (fdsz < sizeof(fd_mask))
262 fdsz = sizeof(fd_mask);
263
264 while (fdsz <
265 (howmany(ev->ev_fd + 1, NFDBITS) * sizeof(fd_mask)))
266 fdsz *= 2;
267
268 if (fdsz != sop->event_fdsz) {
269 if (select_resize(sop, fdsz)) {
270 check_selectop(sop);
271 return (-1);
272 }
273 }
274
275 sop->event_fds = ev->ev_fd;
276 }
277
278 if (ev->ev_events & EV_READ) {
279 FD_SET(ev->ev_fd, sop->event_readset_in);
280 sop->event_r_by_fd[ev->ev_fd] = ev;
281 }
282 if (ev->ev_events & EV_WRITE) {
283 FD_SET(ev->ev_fd, sop->event_writeset_in);
284 sop->event_w_by_fd[ev->ev_fd] = ev;
285 }
286 check_selectop(sop);
287
288 return (0);
289 }
290
291 /*
292 * Nothing to be done here.
293 */
294
295 static int
select_del(void * arg,struct event * ev)296 select_del(void *arg, struct event *ev)
297 {
298 struct selectop *sop = arg;
299
300 check_selectop(sop);
301 if (ev->ev_events & EV_SIGNAL)
302 return (evsignal_del(ev));
303
304 if (sop->event_fds < ev->ev_fd) {
305 check_selectop(sop);
306 return (0);
307 }
308
309 if (ev->ev_events & EV_READ) {
310 FD_CLR(ev->ev_fd, sop->event_readset_in);
311 sop->event_r_by_fd[ev->ev_fd] = NULL;
312 }
313
314 if (ev->ev_events & EV_WRITE) {
315 FD_CLR(ev->ev_fd, sop->event_writeset_in);
316 sop->event_w_by_fd[ev->ev_fd] = NULL;
317 }
318
319 check_selectop(sop);
320 return (0);
321 }
322
323 static void
select_dealloc(struct event_base * base,void * arg)324 select_dealloc(struct event_base *base, void *arg)
325 {
326 struct selectop *sop = arg;
327
328 evsignal_dealloc(base);
329 free(sop->event_readset_in);
330 free(sop->event_writeset_in);
331 free(sop->event_readset_out);
332 free(sop->event_writeset_out);
333 free(sop->event_r_by_fd);
334 free(sop->event_w_by_fd);
335
336 memset(sop, 0, sizeof(struct selectop));
337 free(sop);
338 }
339