bsd-poll.c revision 323134 
1/*
2 * Copyright (c) 2004, 2005, 2007 Darren Tucker (dtucker at zip com au).
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16
17#include "includes.h"
18#if !defined(HAVE_POLL)
19
20#include <sys/types.h>
21#include <sys/time.h>
22#ifdef HAVE_SYS_SELECT_H
23# include <sys/select.h>
24#endif
25
26#include <errno.h>
27#include <stdlib.h>
28#include <unistd.h>
29#include "bsd-poll.h"
30
31/*
32 * A minimal implementation of poll(2), built on top of select(2).
33 *
34 * Only supports POLLIN and POLLOUT flags in pfd.events, and POLLIN, POLLOUT
35 * and POLLERR flags in revents.
36 *
37 * Supports pfd.fd = -1 meaning "unused" although it's not standard.
38 */
39
40int
41poll(struct pollfd *fds, nfds_t nfds, int timeout)
42{
43	nfds_t i;
44	int saved_errno, ret, fd, maxfd = 0;
45	fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
46	size_t nmemb;
47	struct timeval tv, *tvp = NULL;
48
49	for (i = 0; i < nfds; i++) {
50		fd = fds[i].fd;
51		if (fd >= FD_SETSIZE) {
52			errno = EINVAL;
53			return -1;
54		}
55		maxfd = MAX(maxfd, fd);
56	}
57
58	nmemb = howmany(maxfd + 1 , NFDBITS);
59	if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
60	    (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
61	    (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
62		saved_errno = ENOMEM;
63		ret = -1;
64		goto out;
65	}
66
67	/* populate event bit vectors for the events we're interested in */
68	for (i = 0; i < nfds; i++) {
69		fd = fds[i].fd;
70		if (fd == -1)
71			continue;
72		if (fds[i].events & POLLIN) {
73			FD_SET(fd, readfds);
74			FD_SET(fd, exceptfds);
75		}
76		if (fds[i].events & POLLOUT) {
77			FD_SET(fd, writefds);
78			FD_SET(fd, exceptfds);
79		}
80	}
81
82	/* poll timeout is msec, select is timeval (sec + usec) */
83	if (timeout >= 0) {
84		tv.tv_sec = timeout / 1000;
85		tv.tv_usec = (timeout % 1000) * 1000;
86		tvp = &tv;
87	}
88
89	ret = select(maxfd + 1, readfds, writefds, exceptfds, tvp);
90	saved_errno = errno;
91
92	/* scan through select results and set poll() flags */
93	for (i = 0; i < nfds; i++) {
94		fd = fds[i].fd;
95		fds[i].revents = 0;
96		if (fd == -1)
97			continue;
98		if (FD_ISSET(fd, readfds)) {
99			fds[i].revents |= POLLIN;
100		}
101		if (FD_ISSET(fd, writefds)) {
102			fds[i].revents |= POLLOUT;
103		}
104		if (FD_ISSET(fd, exceptfds)) {
105			fds[i].revents |= POLLERR;
106		}
107	}
108
109out:
110	free(readfds);
111	free(writefds);
112	free(exceptfds);
113	if (ret == -1)
114		errno = saved_errno;
115	return ret;
116}
117#endif
118