348 lines
12 KiB
C
348 lines
12 KiB
C
/****************************************************************************
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* sched/signal/sig_nanosleep.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 <time.h>
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#include <signal.h>
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#include <assert.h>
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#include <errno.h>
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#include <nuttx/clock.h>
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#include <nuttx/irq.h>
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#include <nuttx/signal.h>
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#include <nuttx/cancelpt.h>
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#include "clock/clock.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxsig_nanosleep
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*
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* Description:
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* The nxsig_nanosleep() function causes the current thread to be
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* suspended from execution until either the time interval specified by
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* the rqtp argument has elapsed or a signal is delivered to the calling
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* thread and its action is to invoke a signal-catching function or to
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* terminate the process. The suspension time may be longer than requested
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* because the argument value is rounded up to an integer multiple of the
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* sleep resolution or because of the scheduling of other activity by the
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* system. But, except for the case of being interrupted by a signal, the
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* suspension time will not be less than the time specified by rqtp, as
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* measured by the system clock, CLOCK_REALTIME.
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*
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* The use of the nxsig_nanosleep() function has no effect on the action
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* or blockage of any signal.
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*
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* Input Parameters:
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* rqtp - The amount of time to be suspended from execution.
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* rmtp - If the rmtp argument is non-NULL, the timespec structure
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* referenced by it is updated to contain the amount of time
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* remaining in the interval (the requested time minus the time
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* actually slept)
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*
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* Returned Value:
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* If the nxsig_nanosleep() function returns because the requested time
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* has elapsed, its return value is zero.
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*
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* If the nxsig_nanosleep() function returns because it has been
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* interrupted by a signal, the function returns a negated errno value
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* indicate the interruption. If the rmtp argument is non-NULL, the
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* timespec structure referenced by it is updated to contain the amount
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* of time remaining in the interval (the requested time minus the time
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* actually slept). If the rmtp argument is NULL, the remaining time is
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* not returned.
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*
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* If nxsig_nanosleep() fails, it returns a negated errno indicating the
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* cause of the failure. The nxsig_nanosleep() function will fail if:
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*
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* EINTR - The nxsig_nanosleep() function was interrupted by a signal.
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* EINVAL - The rqtp argument specified a nanosecond value less than
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* zero or greater than or equal to 1000 million.
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* ENOSYS - The nxsig_nanosleep() function is not supported by this
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* implementation.
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*
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****************************************************************************/
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int nxsig_nanosleep(FAR const struct timespec *rqtp,
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FAR struct timespec *rmtp)
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{
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irqstate_t flags;
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clock_t starttick;
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sigset_t set;
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int ret;
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/* Sanity check */
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if (rqtp == NULL || rqtp->tv_nsec < 0 || rqtp->tv_nsec >= 1000000000)
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{
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return -EINVAL;
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}
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/* If rqtp is zero, yield CPU and return
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* Notice: The behavior of sleep(0) is not defined in POSIX, so there are
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* different implementations:
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* 1. In Linux, nanosleep(0) will call schedule() to yield CPU:
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* https://elixir.bootlin.com/linux/latest/source/kernel/time/
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* hrtimer.c#L2038
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* 2. In BSD, nanosleep(0) will return immediately:
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* https://github.com/freebsd/freebsd-src/blob/
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* 475fa89800086718bd9249fd4dc3f862549f1f78/crypto/openssh/
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* openbsd-compat/bsd-misc.c#L243
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*/
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if (rqtp->tv_sec == 0 && rqtp->tv_nsec == 0)
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{
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sched_yield();
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return OK;
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}
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/* Get the start time of the wait. Interrupts are disabled to prevent
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* timer interrupts while we do tick-related calculations before and
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* after the wait.
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*/
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flags = enter_critical_section();
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starttick = clock_systime_ticks();
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/* Set up for the sleep. Using the empty set means that we are not
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* waiting for any particular signal. However, any unmasked signal can
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* still awaken nxsig_timedwait().
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*/
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sigemptyset(&set);
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/* nxsig_nanosleep is a simple application of nxsig_timedwait. */
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ret = nxsig_timedwait(&set, NULL, rqtp);
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/* nxsig_timedwait() cannot succeed. It should always return error with
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* either (1) EAGAIN meaning that the timeout occurred, or (2) EINTR
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* meaning that some other unblocked signal was caught.
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*/
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if (ret == -EAGAIN)
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{
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/* The timeout "error" is the normal, successful result */
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leave_critical_section(flags);
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return OK;
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}
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/* If we get there, the wait has failed because we were awakened by a
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* signal. Return the amount of "unwaited" time if rmtp is non-NULL.
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*/
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if (rmtp)
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{
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clock_t elapsed;
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clock_t remaining;
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sclock_t ticks;
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/* REVISIT: The conversion from time to ticks and back could
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* be avoided. clock_timespec_subtract() would be used instead
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* to get the time difference.
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*/
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/* First get the number of clock ticks that we were requested to
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* wait.
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*/
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clock_time2ticks(rqtp, &ticks);
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/* Get the number of ticks that we actually waited */
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elapsed = clock_systime_ticks() - starttick;
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/* The difference between the number of ticks that we were requested
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* to wait and the number of ticks that we actually waited is that
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* amount of time that we failed to wait.
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*/
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if (elapsed >= (clock_t)ticks)
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{
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remaining = 0;
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}
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else
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{
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remaining = (clock_t)ticks - elapsed;
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}
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clock_ticks2time((sclock_t)remaining, rmtp);
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}
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leave_critical_section(flags);
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return ret;
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}
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/****************************************************************************
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* Name: clock_nanosleep
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*
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* Description:
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* If the flag TIMER_ABSTIME is not set in the flags argument, the
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* clock_nanosleep() function will cause the current thread to be suspended
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* from execution until either the time interval specified by the rqtp
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* argument has elapsed, or a signal is delivered to the calling thread
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* and its action is to invoke a signal-catching function, or the process
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* is terminated. The clock used to measure the time will be the clock
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* specified by clock_id.
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*
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* If the flag TIMER_ABSTIME is set in the flags argument, the
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* clock_nanosleep() function will cause the current thread to be
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* suspended from execution until either the time value of the clock
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* specified by clock_id reaches the absolute time specified by the rqtp
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* argument, or a signal is delivered to the calling thread and its action
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* is to invoke a signal-catching function, or the process is terminated.
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* If, at the time of the call, the time value specified by rqtp is less
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* than or equal to the time value of the specified clock, then
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* clock_nanosleep() will return immediately and the calling process will
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* not be suspended.
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*
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* The suspension time caused by this function may be longer than requested
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* because the argument value is rounded up to an integer multiple of the
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* sleep resolution, or because of the scheduling of other activity by the
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* system. But, except for the case of being interrupted by a signal, the
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* suspension time for the relative clock_nanosleep() function (that is,
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* with the TIMER_ABSTIME flag not set) will not be less than the time
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* interval specified by rqtp, as measured by the corresponding clock. The
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* suspension for the absolute clock_nanosleep() function (that is, with
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* the TIMER_ABSTIME flag set) will be in effect at least until the value
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* of the corresponding clock reaches the absolute time specified by rqtp,
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* except for the case of being interrupted by a signal.
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*
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* The use of the clock_nanosleep() function will have no effect on the
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* action or blockage of any signal.
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*
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* The clock_nanosleep() function will fail if the clock_id argument refers
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* to the CPU-time clock of the calling thread. It is unspecified whether
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* clock_id values of other CPU-time clocks are allowed.
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*
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* Input Parameters:
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* clockid - The clock to use to interpret the absolute time
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* flags - Open flags. TIMER_ABSTIME is the only supported flag.
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* rqtp - The amount of time to be suspended from execution.
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* rmtp - If the rmtp argument is non-NULL, the timespec structure
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* referenced by it is updated to contain the amount of time
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* remaining in the interval (the requested time minus the time
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* actually slept)
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*
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* Returned Value:
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* If the clock_nanosleep() function returns because the requested time has
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* elapsed, its return value is zero.
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*
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* If the clock_nanosleep() function returns because it has been
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* interrupted by a signal, the function returns a value of -1 and sets
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* errno to indicate the interruption. If the rmtp argument is non-NULL,
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* the timespec structure referenced by it is updated to contain the amount
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* of time remaining in the interval (the requested time minus the time
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* actually slept). If the rmtp argument is NULL, the remaining time is not
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* returned.
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*
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* If clock_nanosleep() fails, it returns a value of errno. The
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* clock_nanosleep() function will fail if:
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*
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* EINTR - The clock_nanosleep() function was interrupted by a signal.
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* EINVAL - The rqtp argument specified a nanosecond value less than
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* zero or greater than or equal to 1000 million. Or the clockid that
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* does not specify a known clock.
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* ENOSYS - The clock_nanosleep() function is not supported by this
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* implementation.
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*
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****************************************************************************/
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int clock_nanosleep(clockid_t clockid, int flags,
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FAR const struct timespec *rqtp,
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FAR struct timespec *rmtp)
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{
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int ret;
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/* clock_nanosleep() is a cancellation point */
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enter_cancellation_point();
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if (clockid < CLOCK_REALTIME || clockid > CLOCK_BOOTTIME)
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{
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leave_cancellation_point();
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return EINVAL;
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}
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/* Check if absolute time is selected */
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if ((flags & TIMER_ABSTIME) != 0)
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{
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struct timespec reltime;
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struct timespec now;
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irqstate_t irqstate;
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/* Calculate the relative time delay. We need to enter a critical
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* section early to assure the relative time is valid from this
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* point in time.
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*/
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irqstate = enter_critical_section();
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ret = clock_gettime(clockid, &now);
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if (ret < 0)
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{
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/* clock_gettime() sets the errno variable */
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leave_critical_section(irqstate);
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leave_cancellation_point();
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return -ret;
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}
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clock_timespec_subtract(rqtp, &now, &reltime);
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/* Now that we have the relative time, the remaining operations
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* are equivalent to nxsig_nanosleep().
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*/
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ret = nxsig_nanosleep(&reltime, rmtp);
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leave_critical_section(irqstate);
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}
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else
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{
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/* In the relative time case, clock_nanosleep() is equivalent to
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* nanosleep. In this case, it is a paper thin wrapper around
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* nxsig_nanosleep().
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*/
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ret = nxsig_nanosleep(rqtp, rmtp);
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}
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/* Check if nxsig_nanosleep() succeeded */
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if (ret < 0)
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{
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/* If not return the errno */
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ret = -ret;
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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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