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- /****************************************************************************
- * sched/signal/sig_pselect.c
- *
- * Copyright (C) 2018 Pinecone Inc. All rights reserved.
- * Author: Xiang Xiao <xiaoxiang@pinecone.net>
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in
- * the documentation and/or other materials provided with the
- * distribution.
- * 3. Neither the name NuttX nor the names of its contributors may be
- * used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
- * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- *
- ****************************************************************************/
- /****************************************************************************
- * Included Files
- ****************************************************************************/
- #include <nuttx/config.h>
- #include <sys/select.h>
- #include <sys/time.h>
- #include "sched/sched.h"
- #include "signal/signal.h"
- /****************************************************************************
- * Public Functions
- ****************************************************************************/
- /****************************************************************************
- * Name: pselect
- *
- * Description:
- * pselect() allows a program to monitor multiple file descriptors, waiting
- * until one or more of the file descriptors become "ready" for some class
- * of I/O operation (e.g., input possible). A file descriptor is
- * considered ready if it is possible to perform the corresponding I/O
- * operation (e.g., read(2)) without blocking.
- *
- * Input Parameters:
- * nfds - the maximum fd number (+1) of any descriptor in any of the
- * three sets.
- * readfds - the set of descriptions to monitor for read-ready events
- * writefds - the set of descriptions to monitor for write-ready events
- * exceptfds - the set of descriptions to monitor for error events
- * timeout - Return at this time if none of these events of interest
- * occur.
- * sigmask - Replace the current signal mask temporarily during execution
- *
- * Returned Value:
- * 0: Timer expired
- * >0: The number of bits set in the three sets of descriptors
- * -1: An error occurred (errno will be set appropriately)
- *
- ****************************************************************************/
- int pselect(int nfds, FAR fd_set *readfds, FAR fd_set *writefds,
- FAR fd_set *exceptfds, FAR const struct timespec *timeout,
- FAR const sigset_t *sigmask)
- {
- FAR struct tcb_s *rtcb = this_task();
- sigset_t saved_sigprocmask;
- irqstate_t flags;
- int ret = ERROR;
- /* Several operations must be performed below: We must determine if any
- * signal is pending and, if not, wait for the signal. Since signals can
- * be posted from the interrupt level, there is a race condition that
- * can only be eliminated by disabling interrupts!
- */
- flags = enter_critical_section();
- /* Save a copy of the old sigprocmask and install
- * the new (temporary) sigprocmask
- */
- saved_sigprocmask = rtcb->sigprocmask;
- if (sigmask)
- {
- rtcb->sigprocmask = *sigmask;
- }
- rtcb->sigwaitmask = NULL_SIGNAL_SET;
- /* Check if there is a pending signal corresponding to one of the
- * signals that will be unblocked by the new sigprocmask.
- */
- if (nxsig_unmask_pendingsignal())
- {
- /* Dispatching one or more of the signals is sufficient to cause
- * us to not wait. Restore the original sigprocmask.
- */
- rtcb->sigprocmask = saved_sigprocmask;
- leave_critical_section(flags);
- set_errno(EINTR);
- }
- else
- {
- FAR struct timeval *timeval = NULL;
- struct timeval timeval_buf;
- /* And call select to do the real work */
- if (timeout)
- {
- timeval_buf.tv_sec = timeout->tv_sec;
- timeval_buf.tv_usec = timeout->tv_nsec / 1000;
- timeval = &timeval_buf;
- }
- ret = select(nfds, readfds, writefds, exceptfds, timeval);
- /* We are running again, restore the original sigprocmask */
- rtcb->sigprocmask = saved_sigprocmask;
- leave_critical_section(flags);
- /* Now, handle the (rare?) case where (a) a blocked signal was received
- * while the task was suspended but (b) restoring the original
- * sigprocmask will unblock the signal.
- */
- nxsig_unmask_pendingsignal();
- }
- return ret;
- }
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