141 lines
4.8 KiB
C
141 lines
4.8 KiB
C
/****************************************************************************
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* sched/signal/sig_ppoll.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <poll.h>
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#include "sched/sched.h"
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#include "signal/signal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: ppoll
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*
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* Description:
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* ppoll() waits for one of a set of file descriptors to become ready to
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* perform I/O. If none of the events requested (and no error) has
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* occurred for any of the file descriptors, then ppoll() blocks until
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* one of the events occurs.
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*
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* Input Parameters:
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* fds - List of structures describing file descriptors to be monitored
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* nfds - The number of entries in the list
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* timeout - Specifies an upper limit on the time for which ppoll() will
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* block. A NULL pointer means an infinite timeout.
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* sigmask - Replace the current signal mask temporarily during execution
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*
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* Returned Value:
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* On success, the number of structures that have non-zero revents fields.
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* A value of 0 indicates that the call timed out and no file descriptors
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* were ready. On error, -1 is returned, and errno is set appropriately:
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*
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* EBADF - An invalid file descriptor was given in one of the sets.
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* EFAULT - The fds address is invalid
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* EINTR - A signal occurred before any requested event.
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* EINVAL - The nfds value exceeds a system limit.
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* ENOMEM - There was no space to allocate internal data structures.
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* ENOSYS - One or more of the drivers supporting the file descriptor
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* does not support the poll method.
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*
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****************************************************************************/
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int ppoll(FAR struct pollfd *fds, nfds_t nfds,
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FAR const struct timespec *timeout_ts,
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FAR const sigset_t *sigmask)
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{
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FAR struct tcb_s *rtcb = this_task();
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sigset_t saved_sigprocmask;
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irqstate_t flags;
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int ret = ERROR;
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/* Several operations must be performed below: We must determine if any
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* signal is pending and, if not, wait for the signal. Since signals can
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* be posted from the interrupt level, there is a race condition that
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* can only be eliminated by disabling interrupts!
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*/
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flags = enter_critical_section();
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/* Save a copy of the old sigprocmask and install
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* the new (temporary) sigprocmask
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*/
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saved_sigprocmask = rtcb->sigprocmask;
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if (sigmask)
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{
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rtcb->sigprocmask = *sigmask;
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}
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sigemptyset(&rtcb->sigwaitmask);
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/* Check if there is a pending signal corresponding to one of the
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* signals that will be unblocked by the new sigprocmask.
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*/
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if (nxsig_unmask_pendingsignal())
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{
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/* Dispatching one or more of the signals is sufficient to cause
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* us to not wait. Restore the original sigprocmask.
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*/
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rtcb->sigprocmask = saved_sigprocmask;
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leave_critical_section(flags);
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set_errno(EINTR);
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}
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else
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{
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int timeout = -1;
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/* And call poll to do the real work */
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if (timeout_ts)
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{
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timeout = timeout_ts->tv_sec * MSEC_PER_SEC +
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NSEC2MSEC(timeout_ts->tv_nsec);
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}
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ret = poll(fds, nfds, timeout);
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/* We are running again, restore the original sigprocmask */
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rtcb->sigprocmask = saved_sigprocmask;
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leave_critical_section(flags);
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/* Now, handle the (rare?) case where (a) a blocked signal was received
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* while the task was suspended but (b) restoring the original
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* sigprocmask will unblock the signal.
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*/
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nxsig_unmask_pendingsignal();
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}
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return ret;
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}
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