source: vendor/3.6.25/lib/replace/poll.c

/*
   Unix SMB/CIFS implementation.
   poll.c - poll wrapper

   This file is based on code from libssh (LGPLv2.1+ at the time it
   was downloaded), thus the following copyrights:

   Copyright (c) 2009-2010 by Andreas Schneider <mail@cynapses.org>
   Copyright (c) 2003-2009 by Aris Adamantiadis
   Copyright (c) 2009 Aleksandar Kanchev
   Copyright (C) Volker Lendecke 2011

     ** NOTE! The following LGPL license applies to the replace
     ** library. This does NOT imply that all of Samba is released
     ** under the LGPL

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 3 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#include "replace.h"
#include "system/select.h"
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>
#endif


int rep_poll(struct pollfd *fds, nfds_t nfds, int timeout)
{
        fd_set rfds, wfds, efds;
        struct timeval tv, *ptv;
        int max_fd;
        int rc;
        nfds_t i;

        if ((fds == NULL) && (nfds != 0)) {
                errno = EFAULT;
                return -1;
        }

        FD_ZERO(&rfds);
        FD_ZERO(&wfds);
        FD_ZERO(&efds);

        rc = 0;
        max_fd = 0;

        /* compute fd_sets and find largest descriptor */
        for (i = 0; i < nfds; i++) {
                if ((fds[i].fd < 0) || (fds[i].fd >= FD_SETSIZE)) {
                        fds[i].revents = POLLNVAL;
                        continue;
                }

                if (fds[i].events & (POLLIN | POLLRDNORM)) {
                        FD_SET(fds[i].fd, &rfds);
                }
                if (fds[i].events & (POLLOUT | POLLWRNORM | POLLWRBAND)) {
                        FD_SET(fds[i].fd, &wfds);
                }
                if (fds[i].events & (POLLPRI | POLLRDBAND)) {
                        FD_SET(fds[i].fd, &efds);
                }
                if (fds[i].fd > max_fd &&
                    (fds[i].events & (POLLIN | POLLOUT | POLLPRI |
                                      POLLRDNORM | POLLRDBAND |
                                      POLLWRNORM | POLLWRBAND))) {
                        max_fd = fds[i].fd;
                }
        }

        if (timeout < 0) {
                ptv = NULL;
        } else {
                ptv = &tv;
                if (timeout == 0) {
                        tv.tv_sec = 0;
                        tv.tv_usec = 0;
                } else {
                        tv.tv_sec = timeout / 1000;
                        tv.tv_usec = (timeout % 1000) * 1000;
                }
        }

        rc = select(max_fd + 1, &rfds, &wfds, &efds, ptv);
        if (rc < 0) {
                return -1;
        }

        for (rc = 0, i = 0; i < nfds; i++) {
                if ((fds[i].fd < 0) || (fds[i].fd >= FD_SETSIZE)) {
                        continue;
                }

                fds[i].revents = 0;

                if (FD_ISSET(fds[i].fd, &rfds)) {
                        int err = errno;
                        int available = 0;
                        int ret;

                        /* support for POLLHUP */
                        ret = ioctl(fds[i].fd, FIONREAD, &available);
                        if ((ret == -1) || (available == 0)) {
                                fds[i].revents |= POLLHUP;
                        } else {
                                fds[i].revents |= fds[i].events
                                        & (POLLIN | POLLRDNORM);
                        }

                        errno = err;
                }
                if (FD_ISSET(fds[i].fd, &wfds)) {
                        fds[i].revents |= fds[i].events
                                & (POLLOUT | POLLWRNORM | POLLWRBAND);
                }
                if (FD_ISSET(fds[i].fd, &efds)) {
                        fds[i].revents |= fds[i].events
                                & (POLLPRI | POLLRDBAND);
                }
                if (fds[i].revents & ~POLLHUP) {
                        rc++;
                }
        }
        return rc;
}