292 lines
6.7 KiB
C
292 lines
6.7 KiB
C
/*
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* Copyright (C) 2005 David Xu <davidxu@freebsd.org>.
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* Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice(s), this list of conditions and the following disclaimer as
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* the first lines of this file unmodified other than the possible
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* addition of one or more copyright notices.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice(s), this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/queue.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pthread.h>
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#include <semaphore.h>
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#include <stdlib.h>
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#include <time.h>
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#include <_semaphore.h>
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#include "un-namespace.h"
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#include "thr_private.h"
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__weak_reference(_sem_init, sem_init);
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__weak_reference(_sem_destroy, sem_destroy);
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__weak_reference(_sem_getvalue, sem_getvalue);
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__weak_reference(_sem_trywait, sem_trywait);
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__weak_reference(_sem_wait, sem_wait);
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__weak_reference(_sem_timedwait, sem_timedwait);
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__weak_reference(_sem_post, sem_post);
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static inline int
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sem_check_validity(sem_t *sem)
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{
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if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC))
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return (0);
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else {
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errno = EINVAL;
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return (-1);
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}
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}
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static sem_t
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sem_alloc(unsigned int value, semid_t semid, int system_sem)
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{
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sem_t sem;
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if (value > SEM_VALUE_MAX) {
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errno = EINVAL;
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return (NULL);
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}
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sem = (sem_t)malloc(sizeof(struct sem));
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if (sem == NULL) {
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errno = ENOSPC;
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return (NULL);
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}
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bzero(sem, sizeof(*sem));
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/*
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* Fortunatly count and nwaiters are adjacency, so we can
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* use umtx_wait to wait on it, umtx_wait needs an address
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* can be accessed as a long interger.
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*/
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sem->count = (u_int32_t)value;
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sem->nwaiters = 0;
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sem->magic = SEM_MAGIC;
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sem->semid = semid;
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sem->syssem = system_sem;
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return (sem);
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}
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int
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_sem_init(sem_t *sem, int pshared, unsigned int value)
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{
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semid_t semid;
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semid = (semid_t)SEM_USER;
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if ((pshared != 0) && (ksem_init(&semid, value) != 0))
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return (-1);
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(*sem) = sem_alloc(value, semid, pshared);
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if ((*sem) == NULL) {
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if (pshared != 0)
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ksem_destroy(semid);
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return (-1);
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}
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return (0);
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}
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int
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_sem_destroy(sem_t *sem)
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{
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int retval;
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if (sem_check_validity(sem) != 0)
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return (-1);
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/*
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* If this is a system semaphore let the kernel track it otherwise
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* make sure there are no waiters.
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*/
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if ((*sem)->syssem != 0)
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retval = ksem_destroy((*sem)->semid);
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else {
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retval = 0;
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(*sem)->magic = 0;
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}
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if (retval == 0)
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free(*sem);
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return (retval);
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}
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int
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_sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
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{
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int retval;
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if (sem_check_validity(sem) != 0)
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return (-1);
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if ((*sem)->syssem != 0)
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retval = ksem_getvalue((*sem)->semid, sval);
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else {
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*sval = (int)(*sem)->count;
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retval = 0;
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}
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return (retval);
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}
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int
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_sem_trywait(sem_t *sem)
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{
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int val;
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if (sem_check_validity(sem) != 0)
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return (-1);
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if ((*sem)->syssem != 0)
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return (ksem_trywait((*sem)->semid));
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while ((val = (*sem)->count) > 0) {
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if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
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return (0);
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}
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errno = EAGAIN;
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return (-1);
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}
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static void
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sem_cancel_handler(void *arg)
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{
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sem_t *sem = arg;
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atomic_add_int(&(*sem)->nwaiters, -1);
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if ((*sem)->nwaiters && (*sem)->count)
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_thr_umtx_wake(&(*sem)->count, 1, 0);
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}
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int
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_sem_wait(sem_t *sem)
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{
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struct pthread *curthread;
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int val, retval;
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if (sem_check_validity(sem) != 0)
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return (-1);
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curthread = _get_curthread();
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if ((*sem)->syssem != 0) {
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_thr_cancel_enter(curthread);
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retval = ksem_wait((*sem)->semid);
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_thr_cancel_leave(curthread);
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return (retval);
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}
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_pthread_testcancel();
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do {
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while ((val = (*sem)->count) > 0) {
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if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
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return (0);
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}
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atomic_add_int(&(*sem)->nwaiters, 1);
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THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
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_thr_cancel_enter(curthread);
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retval = _thr_umtx_wait_uint(&(*sem)->count, 0, NULL, 0);
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_thr_cancel_leave(curthread);
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THR_CLEANUP_POP(curthread, 0);
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atomic_add_int(&(*sem)->nwaiters, -1);
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} while (retval == 0);
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errno = retval;
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return (-1);
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}
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int
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_sem_timedwait(sem_t * __restrict sem,
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const struct timespec * __restrict abstime)
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{
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struct timespec ts, ts2;
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struct pthread *curthread;
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int val, retval;
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if (sem_check_validity(sem) != 0)
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return (-1);
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curthread = _get_curthread();
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if ((*sem)->syssem != 0) {
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_thr_cancel_enter(curthread);
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retval = ksem_timedwait((*sem)->semid, abstime);
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_thr_cancel_leave(curthread);
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return (retval);
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}
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/*
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* The timeout argument is only supposed to
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* be checked if the thread would have blocked.
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*/
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_pthread_testcancel();
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do {
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while ((val = (*sem)->count) > 0) {
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if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1))
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return (0);
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}
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if (abstime == NULL) {
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errno = EINVAL;
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return (-1);
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}
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clock_gettime(CLOCK_REALTIME, &ts);
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TIMESPEC_SUB(&ts2, abstime, &ts);
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atomic_add_int(&(*sem)->nwaiters, 1);
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THR_CLEANUP_PUSH(curthread, sem_cancel_handler, sem);
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_thr_cancel_enter(curthread);
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retval = _thr_umtx_wait_uint((uint32_t*)&(*sem)->count, 0, &ts2, 0);
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_thr_cancel_leave(curthread);
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THR_CLEANUP_POP(curthread, 0);
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atomic_add_int(&(*sem)->nwaiters, -1);
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} while (retval == 0);
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errno = retval;
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return (-1);
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}
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/*
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* sem_post() is required to be safe to call from within
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* signal handlers, these code should work as that.
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*/
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int
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_sem_post(sem_t *sem)
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{
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int retval = 0;
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if (sem_check_validity(sem) != 0)
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return (-1);
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if ((*sem)->syssem != 0)
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return (ksem_post((*sem)->semid));
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atomic_add_rel_int(&(*sem)->count, 1);
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if ((*sem)->nwaiters) {
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retval = _thr_umtx_wake(&(*sem)->count, 1, 0);
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if (retval != 0)
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retval = -1;
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}
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return (retval);
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}
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