xref: /freebsd/crypto/openssh/openbsd-compat/bsd-poll.c (revision 39ee7a7a6bdd1557b1c3532abf60d139798ac88b)
1 /* $Id: bsd-poll.c,v 1.6 2014/02/05 23:44:13 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 
42 int
43 poll(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 
111 out:
112 	free(readfds);
113 	free(writefds);
114 	free(exceptfds);
115 	if (ret == -1)
116 		errno = saved_errno;
117 	return ret;
118 }
119 #endif
120