VLC Player Source Code

				/*****************************************************************************				 * poll.c: I/O event multiplexing				 *****************************************************************************				 * Copyright © 2007 Rémi Denis-Courmont				 * $Id$				 *				 * Author: Rémi Denis-Courmont				 *				 * This program is free software; you can redistribute it and/or modify				 * it under the terms of the GNU General Public License as published by				 * the Free Software Foundation; either version 2 of the License, or				 * (at your option) any later version.				 *				 * This program 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 General Public License for more details.				 *				 * You should have received a copy of the GNU General Public License				 * along with this program; if not, write to the Free Software				 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.				 *****************************************************************************/								#ifdef HAVE_CONFIG_H				# include "config.h"				#endif								#include 				#include 								#ifdef HAVE_POLL				struct pollfd;								int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)				{				    (void)fds; (void)nfds; (void)timeout;				    abort ();				}				#else /* !HAVE_POLL */				#include 				#include 				#include 								int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)				{				    fd_set rdset, wrset, exset;				    struct timeval tv = { 0, 0 };				    int val = -1;								    FD_ZERO (&rdset);				    FD_ZERO (&wrset);				    FD_ZERO (&exset);				    for (unsigned i = 0; i < nfds; i++)				    {				        int fd = fds[i].fd;				        if (val < fd)				            val = fd;								        /* With POSIX, FD_SET & FD_ISSET are not defined if fd is negative or					 * bigger or equal than FD_SETSIZE. That is one of the reasons why VLC					 * uses poll() rather than select(). Most POSIX systems implement					 * fd_set has a bit field with no sanity checks. This is especially bad					 * on systems (such as BSD) that have no process open files limit by					 * default, such that it is quite feasible to get fd >= FD_SETSIZE.					 * The next instructions will result in a buffer overflow if run on					 * a POSIX system, and the later FD_ISSET will do undefined memory					 * access.					 *					 * With Winsock, fd_set is a table of integers. This is awfully slow.					 * However, FD_SET and FD_ISSET silently and safely discard					 * overflows. If it happens we will loose socket events. Note that					 * most (if not all) Winsock SOCKET handles are actually bigger than					 * FD_SETSIZE in terms of absolute value - they are not POSIX file					 * descriptors. From Vista, there is a much nicer WSAPoll(), but Mingw					 * is yet to support it.					 *					 * With BeOS, the situation is unknown (FIXME: document).					 */				        if (fds[i].events & POLLIN)				            FD_SET (fd, &rdset);				        if (fds[i].events & POLLOUT)				            FD_SET (fd, &wrset);				        if (fds[i].events & POLLPRI)				            FD_SET (fd, &exset);				    }								    if (timeout >= 0)				    {				        div_t d = div (timeout, 1000);				        tv.tv_sec = d.quot;				        tv.tv_usec = d.rem * 1000;				    }								    val = select (val + 1, &rdset, &wrset, &exset,				                  (timeout >= 0) ? &tv : NULL);				    if (val == -1)				        return -1;								    for (unsigned i = 0; i < nfds; i++)				    {				        int fd = fds[i].fd;				        fds[i].revents = (FD_ISSET (fd, &rdset) ? POLLIN : 0)				                       | (FD_ISSET (fd, &wrset) ? POLLOUT : 0)				                       | (FD_ISSET (fd, &exset) ? POLLPRI : 0);				    }				    return val;				}				#endif /* !HAVE_POLL */