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sortix--sortix/libc/select.cpp

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2013-03-03 08:21:40 -05:00
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2013.
This file is part of the Sortix C Library.
The Sortix C 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.
The Sortix C 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 the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
select.cpp
Waiting on multiple file descriptors.
*******************************************************************************/
#include <sys/select.h>
#include <poll.h>
extern "C"
int select(int nfds, fd_set* restrict readfds, fd_set* restrict writefds,
fd_set* restrict exceptfds, struct timeval* restrict timeout)
{
const int READ_EVENTS = POLLIN | POLLRDNORM;
const int WRITE_EVENTS = POLLOUT | POLLWRNORM;
const int EXCEPT_EVENTS = POLLERR | POLLHUP;
struct pollfd fds[FD_SETSIZE];
for ( int i = 0; i < nfds; i++ )
{
fds[i].fd = i;
fds[i].events = fds[i].revents = 0;
if ( FD_ISSET(i, readfds) )
fds[i].events |= READ_EVENTS;
if ( FD_ISSET(i, writefds) )
fds[i].events |= WRITE_EVENTS;
if ( FD_ISSET(i, exceptfds) )
fds[i].events |= EXCEPT_EVENTS;
if ( !fds[i].events )
fds[i].fd = -1;
}
struct timespec* timeout_tsp = NULL;
struct timespec timeout_ts;
if ( timeout )
timeout_tsp = &timeout_ts,
timeout_tsp->tv_sec = timeout->tv_sec,
timeout_tsp->tv_nsec = (long) timeout->tv_usec * 1000;
int num_occur = ppoll(fds, nfds, timeout_tsp, NULL);
if ( num_occur < 0 )
return -1;
if ( readfds ) FD_ZERO(readfds);
if ( writefds ) FD_ZERO(writefds);
if ( exceptfds ) FD_ZERO(exceptfds);
int ret = 0;
for ( int i = 0; i < nfds; i++ )
{
if ( !fds[i].events )
continue;
int events = fds[i].revents;
if ( events & READ_EVENTS && readfds ) { FD_SET(i, readfds); ret++; }
if ( events & WRITE_EVENTS && writefds ) { FD_SET(i, writefds); ret++; }
if ( events & EXCEPT_EVENTS && exceptfds ) { FD_SET(i, exceptfds); ret++; }
}
return ret;
}