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vlc/compat/poll.c

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/*****************************************************************************
* poll.c: poll() emulation
*****************************************************************************
* Copyright © 2007-2012 Rémi Denis-Courmont
*
* This program 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 2.1 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser 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 <stdlib.h>
#include <string.h>
#include <errno.h>
#ifndef _WIN32
# include <sys/time.h>
# include <sys/select.h>
# include <fcntl.h>
int (poll) (struct pollfd *fds, unsigned nfds, int timeout)
{
fd_set rdset[1], wrset[1], exset[1];
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 would perform an undefined
* memory read. */
if ((unsigned)fd >= FD_SETSIZE)
{
errno = EINVAL;
return -1;
}
if (fds[i].events & POLLRDNORM)
FD_SET (fd, rdset);
if (fds[i].events & POLLWRNORM)
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)
{
if (errno != EBADF)
return -1;
val = 0;
for (unsigned i = 0; i < nfds; i++)
if (fcntl (fds[i].fd, F_GETFD) == -1)
{
fds[i].revents = POLLNVAL;
val++;
}
else
fds[i].revents = 0;
return val ? val : -1;
}
for (unsigned i = 0; i < nfds; i++)
{
int fd = fds[i].fd;
fds[i].revents = (FD_ISSET (fd, rdset) ? POLLRDNORM : 0)
| (FD_ISSET (fd, wrset) ? POLLWRNORM : 0)
| (FD_ISSET (fd, exset) ? POLLPRI : 0);
}
return val;
}
#else
# include <windows.h>
# include <winsock2.h>
static int poll_compat(struct pollfd *fds, unsigned nfds, int timeout)
{
DWORD to = (timeout >= 0) ? (DWORD)timeout : INFINITE;
if (nfds == 0)
{ /* WSAWaitForMultipleEvents() does not allow zero events */
if (SleepEx(to, TRUE))
{
errno = EINTR;
return -1;
}
return 0;
}
WSAEVENT *evts = malloc(nfds * sizeof (WSAEVENT));
if (evts == NULL)
return -1; /* ENOMEM */
DWORD ret = WSA_WAIT_FAILED;
for (unsigned i = 0; i < nfds; i++)
{
SOCKET fd = fds[i].fd;
long mask = FD_CLOSE;
fd_set rdset, wrset, exset;
FD_ZERO(&rdset);
FD_ZERO(&wrset);
FD_ZERO(&exset);
FD_SET(fd, &exset);
if (fds[i].events & POLLRDNORM)
{
mask |= FD_READ | FD_ACCEPT;
FD_SET(fd, &rdset);
}
if (fds[i].events & POLLWRNORM)
{
mask |= FD_WRITE | FD_CONNECT;
FD_SET(fd, &wrset);
}
if (fds[i].events & POLLPRI)
mask |= FD_OOB;
fds[i].revents = 0;
evts[i] = WSACreateEvent();
if (evts[i] == WSA_INVALID_EVENT)
{
while (i > 0)
WSACloseEvent(evts[--i]);
free(evts);
errno = ENOMEM;
return -1;
}
if (WSAEventSelect(fds[i].fd, evts[i], mask)
&& WSAGetLastError() == WSAENOTSOCK)
fds[i].revents |= POLLNVAL;
struct timeval tv = { 0, 0 };
/* By its horrible design, WSAEnumNetworkEvents() only enumerates
* events that were not already signaled (i.e. it is edge-triggered).
* WSAPoll() would be better in this respect, but worse in others.
* So use WSAEnumNetworkEvents() after manually checking for pending
* events. */
if (select(0, &rdset, &wrset, &exset, &tv) > 0)
{
if (FD_ISSET(fd, &rdset))
fds[i].revents |= fds[i].events & POLLRDNORM;
if (FD_ISSET(fd, &wrset))
fds[i].revents |= fds[i].events & POLLWRNORM;
if (FD_ISSET(fd, &exset))
/* To add pain to injury, POLLERR and POLLPRI cannot be
* distinguished here. */
fds[i].revents |= POLLERR | (fds[i].events & POLLPRI);
}
if (fds[i].revents != 0 && ret == WSA_WAIT_FAILED)
ret = WSA_WAIT_EVENT_0 + i;
}
if (ret == WSA_WAIT_FAILED)
ret = WSAWaitForMultipleEvents(nfds, evts, FALSE, to, TRUE);
unsigned count = 0;
for (unsigned i = 0; i < nfds; i++)
{
WSANETWORKEVENTS ne;
if (WSAEnumNetworkEvents(fds[i].fd, evts[i], &ne))
memset(&ne, 0, sizeof (ne));
WSAEventSelect(fds[i].fd, evts[i], 0);
WSACloseEvent(evts[i]);
if (ne.lNetworkEvents & FD_CONNECT)
{
fds[i].revents |= POLLWRNORM;
if (ne.iErrorCode[FD_CONNECT_BIT] != 0)
fds[i].revents |= POLLERR;
}
if (ne.lNetworkEvents & FD_CLOSE)
{
fds[i].revents |= (fds[i].events & POLLRDNORM) | POLLHUP;
if (ne.iErrorCode[FD_CLOSE_BIT] != 0)
fds[i].revents |= POLLERR;
}
if (ne.lNetworkEvents & FD_ACCEPT)
{
fds[i].revents |= POLLRDNORM;
if (ne.iErrorCode[FD_ACCEPT_BIT] != 0)
fds[i].revents |= POLLERR;
}
if (ne.lNetworkEvents & FD_OOB)
{
fds[i].revents |= POLLPRI;
if (ne.iErrorCode[FD_OOB_BIT] != 0)
fds[i].revents |= POLLERR;
}
if (ne.lNetworkEvents & FD_READ)
{
fds[i].revents |= POLLRDNORM;
if (ne.iErrorCode[FD_READ_BIT] != 0)
fds[i].revents |= POLLERR;
}
if (ne.lNetworkEvents & FD_WRITE)
{
fds[i].revents |= POLLWRNORM;
if (ne.iErrorCode[FD_WRITE_BIT] != 0)
fds[i].revents |= POLLERR;
}
count += fds[i].revents != 0;
}
free(evts);
if (count == 0 && ret == WSA_WAIT_IO_COMPLETION)
{
errno = EINTR;
return -1;
}
return count;
}
int poll(struct pollfd *fds, unsigned nfds, int timeout)
{
if (timeout == -1)
{
/* HACK: In some cases, we lose some events because events are
* destroyed and recreated only when we need to poll. In order to work
* arround this issue, we try to call the poll compat function every
* 100ms (in case of infinite timeout). */
int ret;
while ((ret = poll_compat(fds, nfds, 100)) == 0);
return ret;
}
else
return poll_compat(fds, nfds, timeout);
}
#endif
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