compat/bsd-poll.c

   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 #ifdef HAVE_SYS_SELECT_H
  18 # include <sys/select.h>
  19 #endif
  20
  21 #include <errno.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include "bsd-poll.h"
  25
  26 #ifndef MAX
  27 #define MAX(_a,_b) ((_a) > (_b) ? (_a) : (_b))
  28 #endif
  29
  30 #ifndef howmany
  31 #define howmany(x,y) (((x)+((y)-1))/(y))
  32 #endif
  33
  34 /*
  35  * A minimal implementation of ppoll(2), built on top of pselect(2).
  36  *
  37  * Only supports POLLIN, POLLOUT and POLLPRI flags in pfd.events and
  38  * revents. Notably POLLERR, POLLHUP and POLLNVAL are not supported.
  39  *
  40  * Supports pfd.fd = -1 meaning "unused" although it's not standard.
  41  */
  42
  43 int
  44 ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmoutp,
  45     const sigset_t *sigmask)
  46 {
  47         nfds_t i;
  48         int saved_errno, ret, fd, maxfd = 0;
  49         fd_set *readfds = NULL, *writefds = NULL, *exceptfds = NULL;
  50         size_t nmemb;
  51
  52         for (i = 0; i < nfds; i++) {
  53                 fd = fds[i].fd;
  54                 if (fd != -1 && fd >= FD_SETSIZE) {
  55                         errno = EINVAL;
  56                         return -1;
  57                 }
  58                 maxfd = MAX(maxfd, fd);
  59         }
  60
  61         nmemb = howmany(maxfd + 1 , NFDBITS);
  62         if ((readfds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
  63             (writefds = calloc(nmemb, sizeof(fd_mask))) == NULL ||
  64             (exceptfds = calloc(nmemb, sizeof(fd_mask))) == NULL) {
  65                 saved_errno = ENOMEM;
  66                 ret = -1;
  67                 goto out;
  68         }
  69
  70         /* populate event bit vectors for the events we're interested in */
  71         for (i = 0; i < nfds; i++) {
  72                 fd = fds[i].fd;
  73                 if (fd == -1)
  74                         continue;
  75                 if (fds[i].events & POLLIN)
  76                         FD_SET(fd, readfds);
  77                 if (fds[i].events & POLLOUT)
  78                         FD_SET(fd, writefds);
  79                 if (fds[i].events & POLLPRI)
  80                         FD_SET(fd, exceptfds);
  81         }
  82
  83         ret = pselect(maxfd + 1, readfds, writefds, exceptfds, tmoutp, sigmask);
  84         saved_errno = errno;
  85
  86         /* scan through select results and set poll() flags */
  87         for (i = 0; i < nfds; i++) {
  88                 fd = fds[i].fd;
  89                 fds[i].revents = 0;
  90                 if (fd == -1)
  91                         continue;
  92                 if (FD_ISSET(fd, readfds))
  93                         fds[i].revents |= POLLIN;
  94                 if (FD_ISSET(fd, writefds))
  95                         fds[i].revents |= POLLOUT;
  96                 if (FD_ISSET(fd, exceptfds))
  97                         fds[i].revents |= POLLPRI;
  98         }
  99
 100 out:
 101         free(readfds);
 102         free(writefds);
 103         free(exceptfds);
 104         if (ret == -1)
 105                 errno = saved_errno;
 106         return ret;
 107 }
 108
 109 #if 0
 110 int
 111 poll(struct pollfd *fds, nfds_t nfds, int timeout)
 112 {
 113         struct timespec ts, *tsp = NULL;
 114
 115         /* poll timeout is msec, ppoll is timespec (sec + nsec) */
 116         if (timeout >= 0) {
 117                 ts.tv_sec = timeout / 1000;
 118                 ts.tv_nsec = (timeout % 1000) * 1000000;
 119                 tsp = &ts;
 120         }
 121
 122         return ppoll(fds, nfds, tsp, NULL);
 123 }
 124 #endif