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 
40 int
poll(struct pollfd * fds,nfds_t nfds,int timeout)41 poll(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 
109 out:
110 	free(readfds);
111 	free(writefds);
112 	free(exceptfds);
113 	if (ret == -1)
114 		errno = saved_errno;
115 	return ret;
116 }
117 #endif
118