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      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
     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