1 /*****************************************************************************
2 * poll.c: I/O event multiplexing
3 *****************************************************************************
4 * Copyright © 2007 Rémi Denis-Courmont
7 * Author: Rémi Denis-Courmont
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
22 *****************************************************************************/
28 #include <vlc_common.h>
30 #include <vlc_network.h>
38 int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
40 struct timespec tsbuf, *ts;
46 div_t d = div (timeout, 1000);
47 tsbuf.tv_sec = d.quot;
48 tsbuf.tv_nsec = d.rem * 1000000;
54 pthread_sigmask (SIG_BLOCK, NULL, &set);
55 sigdelset (&set, SIGRTMIN);
57 canc = vlc_savecancel ();
58 ret = ppoll (fds, nfds, ts, &set);
59 vlc_restorecancel (canc);
65 #elif defined (HAVE_POLL)
68 int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
70 (void)fds; (void)nfds; (void)timeout;
73 #else /* !HAVE_POLL */
77 int vlc_poll (struct pollfd *fds, unsigned nfds, int timeout)
79 fd_set rdset, wrset, exset;
80 struct timeval tv = { 0, 0 };
90 for (unsigned i = 0; i < nfds; i++)
96 /* With POSIX, FD_SET & FD_ISSET are not defined if fd is negative or
97 * bigger or equal than FD_SETSIZE. That is one of the reasons why VLC
98 * uses poll() rather than select(). Most POSIX systems implement
99 * fd_set has a bit field with no sanity checks. This is especially bad
100 * on systems (such as BSD) that have no process open files limit by
101 * default, such that it is quite feasible to get fd >= FD_SETSIZE.
102 * The next instructions will result in a buffer overflow if run on
103 * a POSIX system, and the later FD_ISSET will do undefined memory
106 * With Winsock, fd_set is a table of integers. This is awfully slow.
107 * However, FD_SET and FD_ISSET silently and safely discard
108 * overflows. If it happens we will loose socket events. Note that
109 * most (if not all) Winsock SOCKET handles are actually bigger than
110 * FD_SETSIZE in terms of absolute value - they are not POSIX file
111 * descriptors. From Vista, there is a much nicer WSAPoll(), but Mingw
112 * is yet to support it.
114 * With BeOS, the situation is unknown (FIXME: document).
116 if (fds[i].events & POLLIN)
118 if (fds[i].events & POLLOUT)
120 if (fds[i].events & POLLPRI)
124 #ifndef HAVE_ALERTABLE_SELECT
125 # warning FIXME! Fix cancellation and remove this crap.
126 if ((timeout < 0) || (timeout > 50))
135 div_t d = div (timeout, 1000);
137 tv.tv_usec = d.rem * 1000;
140 val = select (val + 1, &rdset, &wrset, &exset,
141 /*(timeout >= 0) ?*/ &tv /*: NULL*/);
143 #ifndef HAVE_ALERTABLE_SELECT
147 timeout -= (timeout > 50) ? 50 : timeout;
156 for (unsigned i = 0; i < nfds; i++)
159 fds[i].revents = (FD_ISSET (fd, &rdset) ? POLLIN : 0)
160 | (FD_ISSET (fd, &wrset) ? POLLOUT : 0)
161 | (FD_ISSET (fd, &exset) ? POLLPRI : 0);
165 #endif /* !HAVE_POLL */