bsd-poll.c revision 262566 
1/* $Id: bsd-poll.c,v 1.5 2013/11/08 10:12:58 dtucker Exp $ */
2
3/*
4 * Copyright (c) 2004, 2005, 2007 Darren Tucker (dtucker at zip com au).
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include "includes.h"
20#if !defined(HAVE_POLL)
21
22#include <sys/types.h>
23#include <sys/time.h>
24#ifdef HAVE_SYS_SELECT_H
25# include <sys/select.h>
26#endif
27
28#include <errno.h>
29#include <stdlib.h>
30#include <unistd.h>
31#include "bsd-poll.h"
32
33/*
34 * A minimal implementation of poll(2), built on top of select(2).
35 *
36 * Only supports POLLIN and POLLOUT flags in pfd.events, and POLLIN, POLLOUT
37 * and POLLERR flags in revents.
38 *
39 * Supports pfd.fd = -1 meaning "unused" although it's not standard.
40 */
41
42int
43poll(struct pollfd *fds, nfds_t nfds, int timeout)
44{
45	nfds_t i;
46	int saved_errno, ret, fd, maxfd = 0;
47	fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
48	size_t nmemb;
49	struct timeval tv, *tvp = NULL;
50
51	for (i = 0; i < nfds; i++) {
52		fd = fds[i].fd;
53		if (fd >= FD_SETSIZE) {
54			errno = EINVAL;
55			return -1;
56		}
57		maxfd = MAX(maxfd, fd);
58	}
59
60	nmemb = howmany(maxfd + 1 , NFDBITS);
61	if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
62	    (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
63	    (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
64		saved_errno = ENOMEM;
65		ret = -1;
66		goto out;
67	}
68
69	/* populate event bit vectors for the events we're interested in */
70	for (i = 0; i < nfds; i++) {
71		fd = fds[i].fd;
72		if (fd == -1)
73			continue;
74		if (fds[i].events & POLLIN) {
75			FD_SET(fd, readfds);
76			FD_SET(fd, exceptfds);
77		}
78		if (fds[i].events & POLLOUT) {
79			FD_SET(fd, writefds);
80			FD_SET(fd, exceptfds);
81		}
82	}
83
84	/* poll timeout is msec, select is timeval (sec + usec) */
85	if (timeout >= 0) {
86		tv.tv_sec = timeout / 1000;
87		tv.tv_usec = (timeout % 1000) * 1000;
88		tvp = &tv;
89	}
90
91	ret = select(maxfd + 1, readfds, writefds, exceptfds, tvp);
92	saved_errno = errno;
93
94	/* scan through select results and set poll() flags */
95	for (i = 0; i < nfds; i++) {
96		fd = fds[i].fd;
97		fds[i].revents = 0;
98		if (fd == -1)
99			continue;
100		if (FD_ISSET(fd, readfds)) {
101			fds[i].revents |= POLLIN;
102		}
103		if (FD_ISSET(fd, writefds)) {
104			fds[i].revents |= POLLOUT;
105		}
106		if (FD_ISSET(fd, exceptfds)) {
107			fds[i].revents |= POLLERR;
108		}
109	}
110
111out:
112	if (readfds != NULL)
113		free(readfds);
114	if (writefds != NULL)
115		free(writefds);
116	if (exceptfds != NULL)
117		free(exceptfds);
118	if (ret == -1)
119		errno = saved_errno;
120	return ret;
121}
122#endif
123