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132 lines
4.2 KiB
132 lines
4.2 KiB
/*****************************************************************************
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* poll.c: poll() emulation
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*****************************************************************************
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* Copyright © 2007-2012 Rémi Denis-Courmont
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2.1 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
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*****************************************************************************/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#ifdef _WIN32
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# ifdef FD_SETSIZE
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/* Too late for #undef FD_SETSIZE to work: fd_set is already defined. */
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# error Header inclusion order compromised!
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# endif
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# define FD_SETSIZE 0
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# include <winsock2.h>
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#else
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# include <sys/time.h>
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# include <sys/select.h>
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#endif
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int (poll) (struct pollfd *fds, unsigned nfds, int timeout)
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{
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#ifdef _WIN32
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size_t setsize = sizeof (fd_set) + nfds * sizeof (SOCKET);
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fd_set *rdset = malloc (setsize);
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fd_set *wrset = malloc (setsize);
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fd_set *exset = malloc (setsize);
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if (rdset == NULL || wrset == NULL || exset == NULL)
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{
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free (rdset);
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free (wrset);
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free (exset);
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errno = ENOMEM;
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return -1;
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}
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/* Winsock FD_SET uses FD_SETSIZE in its expansion */
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# undef FD_SETSIZE
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# define FD_SETSIZE (nfds)
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#else
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fd_set rdset[1], wrset[1], exset[1];
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#endif
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struct timeval tv = { 0, 0 };
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int val = -1;
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FD_ZERO (rdset);
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FD_ZERO (wrset);
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FD_ZERO (exset);
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for (unsigned i = 0; i < nfds; i++)
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{
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int fd = fds[i].fd;
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if (val < fd)
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val = fd;
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/* With POSIX, FD_SET & FD_ISSET are not defined if fd is negative or
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* bigger or equal than FD_SETSIZE. That is one of the reasons why VLC
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* uses poll() rather than select(). Most POSIX systems implement
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* fd_set has a bit field with no sanity checks. This is especially bad
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* on systems (such as BSD) that have no process open files limit by
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* default, such that it is quite feasible to get fd >= FD_SETSIZE.
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* The next instructions will result in a buffer overflow if run on
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* a POSIX system, and the later FD_ISSET would perform an undefined
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* memory read.
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*
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* With Winsock, fd_set is a table of integers. This is awfully slow.
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* However, FD_SET and FD_ISSET silently and safely discard excess
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* entries. Here, overflow cannot happen anyway: fd_set of adequate
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* size are allocated.
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* Note that Vista has a much nicer WSAPoll(), but Mingw does not
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* support it yet.
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*/
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#ifndef _WIN32
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if ((unsigned)fd >= FD_SETSIZE)
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{
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errno = EINVAL;
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return -1;
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}
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#endif
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if (fds[i].events & POLLIN)
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FD_SET (fd, rdset);
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if (fds[i].events & POLLOUT)
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FD_SET (fd, wrset);
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if (fds[i].events & POLLPRI)
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FD_SET (fd, exset);
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}
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if (timeout >= 0)
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{
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div_t d = div (timeout, 1000);
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tv.tv_sec = d.quot;
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tv.tv_usec = d.rem * 1000;
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}
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val = select (val + 1, rdset, wrset, exset,
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(timeout >= 0) ? &tv : NULL);
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if (val == -1)
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return -1;
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for (unsigned i = 0; i < nfds; i++)
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{
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int fd = fds[i].fd;
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fds[i].revents = (FD_ISSET (fd, rdset) ? POLLIN : 0)
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| (FD_ISSET (fd, wrset) ? POLLOUT : 0)
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| (FD_ISSET (fd, exset) ? POLLPRI : 0);
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}
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#ifdef _WIN32
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free (exset);
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free (wrset);
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free (rdset);
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#endif
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return val;
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}
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