openbsd-compat/bsd-poll.c

   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