mirror of
https://gitlab.com/sortix/sortix.git
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74 lines
2.4 KiB
C++
74 lines
2.4 KiB
C++
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/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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select.cpp
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Waiting on multiple file descriptors.
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*******************************************************************************/
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#include <sys/select.h>
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#include <poll.h>
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extern "C"
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int select(int nfds, fd_set* restrict readfds, fd_set* restrict writefds,
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fd_set* restrict exceptfds, struct timeval* restrict timeout)
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{
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const int READ_EVENTS = POLLIN | POLLRDNORM;
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const int WRITE_EVENTS = POLLOUT | POLLWRNORM;
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const int EXCEPT_EVENTS = POLLERR | POLLHUP;
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struct pollfd fds[FD_SETSIZE];
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for ( int i = 0; i < nfds; i++ )
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{
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fds[i].fd = i;
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fds[i].events = fds[i].revents = 0;
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if ( FD_ISSET(i, readfds) )
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fds[i].events |= READ_EVENTS;
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if ( FD_ISSET(i, writefds) )
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fds[i].events |= WRITE_EVENTS;
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if ( FD_ISSET(i, exceptfds) )
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fds[i].events |= EXCEPT_EVENTS;
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if ( !fds[i].events )
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fds[i].fd = -1;
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}
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struct timespec* timeout_tsp = NULL;
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struct timespec timeout_ts;
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if ( timeout )
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timeout_tsp = &timeout_ts,
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timeout_tsp->tv_sec = timeout->tv_sec,
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timeout_tsp->tv_nsec = (long) timeout->tv_usec * 1000;
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int num_occur = ppoll(fds, nfds, timeout_tsp, NULL);
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if ( num_occur < 0 )
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return -1;
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if ( readfds ) FD_ZERO(readfds);
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if ( writefds ) FD_ZERO(writefds);
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if ( exceptfds ) FD_ZERO(exceptfds);
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int ret = 0;
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for ( int i = 0; i < nfds; i++ )
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{
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if ( !fds[i].events )
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continue;
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int events = fds[i].revents;
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if ( events & READ_EVENTS && readfds ) { FD_SET(i, readfds); ret++; }
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if ( events & WRITE_EVENTS && writefds ) { FD_SET(i, writefds); ret++; }
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if ( events & EXCEPT_EVENTS && exceptfds ) { FD_SET(i, exceptfds); ret++; }
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}
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return ret;
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}
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