1/* $Id: bsd-poll.c,v 1.4 2008/08/29 21:32:38 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#ifdef HAVE_SYS_SELECT_H
23# include <sys/select.h>
24#endif
25
26#include <stdlib.h>
27#include <errno.h>
28#include "bsd-poll.h"
29
30/*
31 * A minimal implementation of poll(2), built on top of select(2).
32 *
33 * Only supports POLLIN and POLLOUT flags in pfd.events, and POLLIN, POLLOUT
34 * and POLLERR flags in revents.
35 *
36 * Supports pfd.fd = -1 meaning "unused" although it's not standard.
37 */
38
39int
40poll(struct pollfd *fds, nfds_t nfds, int timeout)
41{
42	nfds_t i;
43	int saved_errno, ret, fd, maxfd = 0;
44	fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
45	size_t nmemb;
46	struct timeval tv, *tvp = NULL;
47
48	for (i = 0; i < nfds; i++) {
49		fd = fds[i].fd;
50		if (fd >= FD_SETSIZE) {
51			errno = EINVAL;
52			return -1;
53		}
54		maxfd = MAX(maxfd, fd);
55	}
56
57	nmemb = howmany(maxfd + 1 , NFDBITS);
58	if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
59	    (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
60	    (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
61		saved_errno = ENOMEM;
62		ret = -1;
63		goto out;
64	}
65
66	/* populate event bit vectors for the events we're interested in */
67	for (i = 0; i < nfds; i++) {
68		fd = fds[i].fd;
69		if (fd == -1)
70			continue;
71		if (fds[i].events & POLLIN) {
72			FD_SET(fd, readfds);
73			FD_SET(fd, exceptfds);
74		}
75		if (fds[i].events & POLLOUT) {
76			FD_SET(fd, writefds);
77			FD_SET(fd, exceptfds);
78		}
79	}
80
81	/* poll timeout is msec, select is timeval (sec + usec) */
82	if (timeout >= 0) {
83		tv.tv_sec = timeout / 1000;
84		tv.tv_usec = (timeout % 1000) * 1000;
85		tvp = &tv;
86	}
87
88	ret = select(maxfd + 1, readfds, writefds, exceptfds, tvp);
89	saved_errno = errno;
90
91	/* scan through select results and set poll() flags */
92	for (i = 0; i < nfds; i++) {
93		fd = fds[i].fd;
94		fds[i].revents = 0;
95		if (fd == -1)
96			continue;
97		if (FD_ISSET(fd, readfds)) {
98			fds[i].revents |= POLLIN;
99		}
100		if (FD_ISSET(fd, writefds)) {
101			fds[i].revents |= POLLOUT;
102		}
103		if (FD_ISSET(fd, exceptfds)) {
104			fds[i].revents |= POLLERR;
105		}
106	}
107
108out:
109	if (readfds != NULL)
110		free(readfds);
111	if (writefds != NULL)
112		free(writefds);
113	if (exceptfds != NULL)
114		free(exceptfds);
115	if (ret == -1)
116		errno = saved_errno;
117	return ret;
118}
119#endif
120