543 lines
17 KiB
C
543 lines
17 KiB
C
/****************************************************************************
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* sched/signal/sig_timedwait.c
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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 <nuttx/compiler.h>
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#include <stdint.h>
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#include <string.h>
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#include <signal.h>
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#include <time.h>
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#include <assert.h>
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#include <debug.h>
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#include <sched.h>
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#include <errno.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include <nuttx/wdog.h>
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#include <nuttx/signal.h>
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#include <nuttx/cancelpt.h>
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#include <nuttx/queue.h>
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#include "sched/sched.h"
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#include "signal/signal.h"
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#include "clock/clock.h"
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/* These are special values of si_signo that mean that either the wait was
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* awakened with a timeout, or the wait was canceled... not the receipt of a
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* signal.
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*/
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#define SIG_CANCEL_TIMEOUT 0xfe
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#define SIG_WAIT_TIMEOUT 0xff
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsig_timeout
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*
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* Description:
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* A timeout elapsed while waiting for signals to be queued.
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*
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* Assumptions:
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* This function executes in the context of the timer interrupt handler.
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* Local interrupts are assumed to be disabled on entry.
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*
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****************************************************************************/
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static void nxsig_timeout(wdparm_t arg)
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{
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FAR struct tcb_s *wtcb = (FAR struct tcb_s *)(uintptr_t)arg;
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#ifdef CONFIG_SMP
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irqstate_t flags;
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/* We must be in a critical section in order to call up_switch_context()
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* below. If we are running on a single CPU architecture, then we know
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* interrupts a disabled an there is no need to explicitly call
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* enter_critical_section(). However, in the SMP case,
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* enter_critical_section() does much more than just disable interrupts on
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* the local CPU; it also manages spinlocks to assure the stability of the
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* TCB that we are manipulating.
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*/
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flags = enter_critical_section();
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#endif
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/* There may be a race condition -- make sure the task is
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* still waiting for a signal
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*/
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if (wtcb->task_state == TSTATE_WAIT_SIG)
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{
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FAR struct tcb_s *rtcb = this_task();
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wtcb->sigunbinfo.si_signo = SIG_WAIT_TIMEOUT;
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wtcb->sigunbinfo.si_code = SI_TIMER;
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wtcb->sigunbinfo.si_errno = ETIMEDOUT;
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wtcb->sigunbinfo.si_value.sival_int = 0;
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#ifdef CONFIG_SCHED_HAVE_PARENT
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wtcb->sigunbinfo.si_pid = 0; /* Not applicable */
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wtcb->sigunbinfo.si_status = OK;
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#endif
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/* Remove the task from waitting list */
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dq_rem((FAR dq_entry_t *)wtcb, &g_waitingforsignal);
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/* Add the task to ready-to-run task list, and
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* perform the context switch if one is needed
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*/
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if (nxsched_add_readytorun(wtcb))
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{
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up_switch_context(wtcb, rtcb);
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}
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}
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#ifdef CONFIG_SMP
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leave_critical_section(flags);
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#endif
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsig_wait_irq
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*
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* Description:
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* An error event has occurred and the signal wait must be terminated with
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* an error.
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*
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****************************************************************************/
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#ifdef CONFIG_CANCELLATION_POINTS
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void nxsig_wait_irq(FAR struct tcb_s *wtcb, int errcode)
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{
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#ifdef CONFIG_SMP
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irqstate_t flags;
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/* We must be in a critical section in order to call up_switch_context()
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* below. If we are running on a single CPU architecture, then we know
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* interrupts a disabled an there is no need to explicitly call
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* enter_critical_section(). However, in the SMP case,
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* enter_critical_section() does much more than just disable interrupts on
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* the local CPU; it also manages spinlocks to assure the stability of the
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* TCB that we are manipulating.
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*/
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flags = enter_critical_section();
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#endif
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/* There may be a race condition -- make sure the task is
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* still waiting for a signal
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*/
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if (wtcb->task_state == TSTATE_WAIT_SIG)
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{
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FAR struct tcb_s *rtcb = this_task();
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wtcb->sigunbinfo.si_signo = SIG_CANCEL_TIMEOUT;
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wtcb->sigunbinfo.si_code = SI_USER;
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wtcb->sigunbinfo.si_errno = errcode;
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wtcb->sigunbinfo.si_value.sival_int = 0;
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#ifdef CONFIG_SCHED_HAVE_PARENT
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wtcb->sigunbinfo.si_pid = 0; /* Not applicable */
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wtcb->sigunbinfo.si_status = OK;
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#endif
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/* Remove the task from waitting list */
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dq_rem((FAR dq_entry_t *)wtcb, &g_waitingforsignal);
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/* Add the task to ready-to-run task list, and
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* perform the context switch if one is needed
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*/
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if (nxsched_add_readytorun(wtcb))
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{
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up_switch_context(wtcb, rtcb);
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}
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}
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#ifdef CONFIG_SMP
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leave_critical_section(flags);
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#endif
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}
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#endif /* CONFIG_CANCELLATION_POINTS */
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/****************************************************************************
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* Name: nxsig_timedwait
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*
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* Description:
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* This function selects the pending signal set specified by the argument
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* set. If multiple signals are pending in set, it will remove and return
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* the lowest numbered one. If no signals in set are pending at the time
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* of the call, the calling process will be suspended until one of the
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* signals in set becomes pending, OR until the process is interrupted by
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* an unblocked signal, OR until the time interval specified by timeout
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* (if any), has expired. If timeout is NULL, then the timeout interval
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* is forever.
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*
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* If the info argument is non-NULL, the selected signal number is stored
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* in the si_signo member and the cause of the signal is stored in the
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* si_code member. The content of si_value is only meaningful if the
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* signal was generated by sigqueue() (or nxsig_queue).
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*
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* This is an internal OS interface. It is functionally equivalent to
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* sigtimedwait() except that:
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*
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* - It is not a cancellation point, and
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* - It does not modify the errno value.
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*
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* Input Parameters:
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* set - The pending signal set.
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* info - The returned value (may be NULL).
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* timeout - The amount of time to wait (may be NULL)
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*
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* Returned Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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*
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* EAGAIN - No signal specified by set was generated within the specified
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* timeout period.
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* EINTR - The wait was interrupted by an unblocked, caught signal.
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*
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****************************************************************************/
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int nxsig_timedwait(FAR const sigset_t *set, FAR struct siginfo *info,
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FAR const struct timespec *timeout)
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{
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FAR struct tcb_s *rtcb = this_task();
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sigset_t intersection;
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FAR sigpendq_t *sigpend;
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irqstate_t flags;
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sclock_t waitticks;
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bool switch_needed;
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int ret;
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DEBUGASSERT(set != NULL);
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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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/* Check if there is a pending signal corresponding to one of the
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* signals in the pending signal set argument.
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*/
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intersection = nxsig_pendingset(rtcb);
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sigandset(&intersection, &intersection, (FAR sigset_t *)set);
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if (!sigisemptyset(&intersection))
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{
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/* One or more of the signals in intersections is sufficient to cause
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* us to not wait. Pick the lowest numbered signal and mark it not
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* pending.
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*/
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sigpend = nxsig_remove_pendingsignal(rtcb,
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nxsig_lowest(&intersection));
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DEBUGASSERT(sigpend);
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/* Return the signal info to the caller if so requested */
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if (info != NULL)
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{
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memcpy(info, &sigpend->info, sizeof(struct siginfo));
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}
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/* The return value is the number of the signal that awakened us */
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ret = sigpend->info.si_signo;
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/* Then dispose of the pending signal structure properly */
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nxsig_release_pendingsignal(sigpend);
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leave_critical_section(flags);
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}
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/* We will have to wait for a signal to be posted to this task. */
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else
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{
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#ifdef CONFIG_CANCELLATION_POINTS
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/* nxsig_timedwait() is not a cancellation point, but it may be called
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* from a cancellation point. So if a cancellation is pending, we
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* must exit immediately without waiting.
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*/
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if (check_cancellation_point())
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{
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/* If there is a pending cancellation, then do not perform
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* the wait. Exit now with ECANCELED.
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*/
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leave_critical_section(flags);
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return -ECANCELED;
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}
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#endif
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/* Check if we should wait for the timeout */
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if (timeout != NULL)
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{
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/* Convert the timespec to system clock ticks, making sure that
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* the resulting delay is greater than or equal to the requested
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* time in nanoseconds.
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*/
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#ifdef CONFIG_SYSTEM_TIME64
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waitticks = ((uint64_t)timeout->tv_sec * NSEC_PER_SEC +
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(uint64_t)timeout->tv_nsec + NSEC_PER_TICK - 1) /
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NSEC_PER_TICK;
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#else
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uint32_t waitmsec;
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DEBUGASSERT(timeout->tv_sec < UINT32_MAX / MSEC_PER_SEC);
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waitmsec = timeout->tv_sec * MSEC_PER_SEC +
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(timeout->tv_nsec + NSEC_PER_MSEC - 1) / NSEC_PER_MSEC;
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waitticks = MSEC2TICK(waitmsec);
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#endif
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if (waitticks > 0)
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{
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/* Save the set of pending signals to wait for */
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rtcb->sigwaitmask = *set;
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/* Start the watchdog */
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wd_start(&rtcb->waitdog, waitticks,
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nxsig_timeout, (uintptr_t)rtcb);
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/* Now wait for either the signal or the watchdog, but
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* first, make sure this is not the idle task,
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* descheduling that isn't going to end well.
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*/
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DEBUGASSERT(!is_idle_task(rtcb));
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/* Remove the tcb task from the ready-to-run list. */
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switch_needed = nxsched_remove_readytorun(rtcb, true);
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/* Add the task to the specified blocked task list */
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rtcb->task_state = TSTATE_WAIT_SIG;
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dq_addlast((FAR dq_entry_t *)rtcb, &g_waitingforsignal);
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/* Now, perform the context switch if one is needed */
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if (switch_needed)
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{
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up_switch_context(this_task(), rtcb);
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}
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/* We no longer need the watchdog */
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wd_cancel(&rtcb->waitdog);
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}
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else
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{
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leave_critical_section(flags);
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return -EAGAIN;
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}
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}
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/* No timeout, just wait */
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else
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{
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/* Save the set of pending signals to wait for */
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rtcb->sigwaitmask = *set;
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/* And wait until one of the unblocked signals is posted,
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* but first make sure this is not the idle task,
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* descheduling that isn't going to end well.
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*/
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DEBUGASSERT(!is_idle_task(rtcb));
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/* Remove the tcb task from the ready-to-run list. */
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switch_needed = nxsched_remove_readytorun(rtcb, true);
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/* Add the task to the specified blocked task list */
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rtcb->task_state = TSTATE_WAIT_SIG;
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dq_addlast((FAR dq_entry_t *)rtcb, &g_waitingforsignal);
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/* Now, perform the context switch if one is needed */
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if (switch_needed)
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{
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up_switch_context(this_task(), rtcb);
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}
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}
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/* We are running again, clear the sigwaitmask */
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sigemptyset(&rtcb->sigwaitmask);
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/* When we awaken, the cause will be in the TCB. Get the signal number
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* or timeout) that awakened us.
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*/
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if (GOOD_SIGNO(rtcb->sigunbinfo.si_signo))
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{
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/* We were awakened by a signal... but is it one of the signals
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* that we were waiting for?
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*/
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if (nxsig_ismember(set, rtcb->sigunbinfo.si_signo))
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{
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/* Return the signal info to the caller if so requested */
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if (info != NULL)
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{
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memcpy(info, &rtcb->sigunbinfo, sizeof(struct siginfo));
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}
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/* Yes.. the return value is the number of the signal that
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* awakened us.
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*/
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ret = rtcb->sigunbinfo.si_signo;
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}
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else
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{
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/* No... then report the EINTR error */
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ret = -EINTR;
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}
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}
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else
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{
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/* Otherwise, we must have been awakened by the timeout or,
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* perhaps, the wait was cancelled.
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*/
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#ifdef CONFIG_CANCELLATION_POINTS
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if (rtcb->sigunbinfo.si_signo == SIG_CANCEL_TIMEOUT)
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{
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/* The wait was canceled */
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ret = -rtcb->sigunbinfo.si_errno;
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DEBUGASSERT(ret < 0);
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}
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else
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#endif
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{
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/* We were awakened by a timeout. Set EAGAIN and return an
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* error.
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*/
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DEBUGASSERT(rtcb->sigunbinfo.si_signo == SIG_WAIT_TIMEOUT);
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ret = -EAGAIN;
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}
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}
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leave_critical_section(flags);
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}
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return ret;
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}
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/****************************************************************************
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* Name: sigtimedwait
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*
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* Description:
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* This function selects the pending signal set specified by the argument
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* set. If multiple signals are pending in set, it will remove and return
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* the lowest numbered one. If no signals in set are pending at the time
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* of the call, the calling process will be suspended until one of the
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* signals in set becomes pending, OR until the process is interrupted by
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* an unblocked signal, OR until the time interval specified by timeout
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* (if any), has expired. If timeout is NULL, then the timeout interval
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* is forever.
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*
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* If the info argument is non-NULL, the selected signal number is stored
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* in the si_signo member and the cause of the signal is stored in the
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* si_code member. The content of si_value is only meaningful if the
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* signal was generated by sigqueue().
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*
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* The following values for si_code are defined in signal.h:
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* SI_USER - Signal sent from kill, raise, or abort
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* SI_QUEUE - Signal sent from sigqueue
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* SI_TIMER - Signal is result of timer expiration
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* SI_ASYNCIO - Signal is the result of asynch IO completion
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* SI_MESGQ - Signal generated by arrival of a message on an
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* empty message queue.
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*
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* Input Parameters:
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* set - The pending signal set.
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* info - The returned value (may be NULL).
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* timeout - The amount of time to wait (may be NULL)
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*
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* Returned Value:
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* Signal number that cause the wait to be terminated, otherwise -1 (ERROR)
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* is returned with errno set to either:
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*
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* EAGAIN - No signal specified by set was generated within the specified
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* timeout period.
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* EINTR - The wait was interrupted by an unblocked, caught signal.
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*
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****************************************************************************/
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int sigtimedwait(FAR const sigset_t *set, FAR struct siginfo *info,
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FAR const struct timespec *timeout)
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{
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int ret;
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/* sigtimedwait() is a cancellation point */
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enter_cancellation_point();
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/* Let nxsig_timedwait() do the work. */
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ret = nxsig_timedwait(set, info, timeout);
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if (ret < 0)
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{
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set_errno(-ret);
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ret = ERROR;
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}
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leave_cancellation_point();
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return ret;
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}
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