Home | History | Annotate | Download | only in openbsd-compat 
      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 
     39 int
     40 poll(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 
    108 out:
    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