diff options
Diffstat (limited to 'lib/libthr/thread/thr_sem.c')
| -rw-r--r-- | lib/libthr/thread/thr_sem.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_sem.c b/lib/libthr/thread/thr_sem.c new file mode 100644 index 0000000..17059e3 --- /dev/null +++ b/lib/libthr/thread/thr_sem.c @@ -0,0 +1,257 @@ +/* + * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice(s), this list of conditions and the following disclaimer as + * the first lines of this file unmodified other than the possible + * addition of one or more copyright notices. + * 2. Redistributions in binary form must reproduce the above copyright + * notice(s), this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY + * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE + * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, + * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <stdlib.h> +#include <errno.h> +#include <semaphore.h> +#include <pthread.h> +#include "thr_private.h" + +#define _SEM_CHECK_VALIDITY(sem) \ + if ((*(sem))->magic != SEM_MAGIC) { \ + errno = EINVAL; \ + retval = -1; \ + goto RETURN; \ + } + +__weak_reference(_sem_init, sem_init); +__weak_reference(_sem_destroy, sem_destroy); +__weak_reference(_sem_open, sem_open); +__weak_reference(_sem_close, sem_close); +__weak_reference(_sem_unlink, sem_unlink); +__weak_reference(_sem_wait, sem_wait); +__weak_reference(_sem_trywait, sem_trywait); +__weak_reference(_sem_post, sem_post); +__weak_reference(_sem_getvalue, sem_getvalue); + + +int +_sem_init(sem_t *sem, int pshared, unsigned int value) +{ + int retval; + + /* + * Range check the arguments. + */ + if (pshared != 0) { + /* + * The user wants a semaphore that can be shared among + * processes, which this implementation can't do. Sounds like a + * permissions problem to me (yeah right). + */ + errno = EPERM; + retval = -1; + goto RETURN; + } + + if (value > SEM_VALUE_MAX) { + errno = EINVAL; + retval = -1; + goto RETURN; + } + + *sem = (sem_t)malloc(sizeof(struct sem)); + if (*sem == NULL) { + errno = ENOSPC; + retval = -1; + goto RETURN; + } + + /* + * Initialize the semaphore. + */ + if (pthread_mutex_init(&(*sem)->lock, NULL) != 0) { + free(*sem); + errno = ENOSPC; + retval = -1; + goto RETURN; + } + + if (pthread_cond_init(&(*sem)->gtzero, NULL) != 0) { + pthread_mutex_destroy(&(*sem)->lock); + free(*sem); + errno = ENOSPC; + retval = -1; + goto RETURN; + } + + (*sem)->count = (u_int32_t)value; + (*sem)->nwaiters = 0; + (*sem)->magic = SEM_MAGIC; + + retval = 0; + RETURN: + return retval; +} + +int +_sem_destroy(sem_t *sem) +{ + int retval; + + _SEM_CHECK_VALIDITY(sem); + + /* Make sure there are no waiters. */ + pthread_mutex_lock(&(*sem)->lock); + if ((*sem)->nwaiters > 0) { + pthread_mutex_unlock(&(*sem)->lock); + errno = EBUSY; + retval = -1; + goto RETURN; + } + pthread_mutex_unlock(&(*sem)->lock); + + pthread_mutex_destroy(&(*sem)->lock); + pthread_cond_destroy(&(*sem)->gtzero); + (*sem)->magic = 0; + + free(*sem); + + retval = 0; + RETURN: + return retval; +} + +sem_t * +_sem_open(const char *name, int oflag, ...) +{ + errno = ENOSYS; + return SEM_FAILED; +} + +int +_sem_close(sem_t *sem) +{ + errno = ENOSYS; + return -1; +} + +int +_sem_unlink(const char *name) +{ + errno = ENOSYS; + return -1; +} + +int +_sem_wait(sem_t *sem) +{ + int retval; + + _thread_enter_cancellation_point(); + + _SEM_CHECK_VALIDITY(sem); + + pthread_mutex_lock(&(*sem)->lock); + + while ((*sem)->count == 0) { + (*sem)->nwaiters++; + pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock); + (*sem)->nwaiters--; + } + (*sem)->count--; + + pthread_mutex_unlock(&(*sem)->lock); + + retval = 0; + RETURN: + _thread_leave_cancellation_point(); + return retval; +} + +int +_sem_trywait(sem_t *sem) +{ + int retval; + + _SEM_CHECK_VALIDITY(sem); + + pthread_mutex_lock(&(*sem)->lock); + + if ((*sem)->count > 0) { + (*sem)->count--; + retval = 0; + } else { + errno = EAGAIN; + retval = -1; + } + + pthread_mutex_unlock(&(*sem)->lock); + + RETURN: + return retval; +} + +int +_sem_post(sem_t *sem) +{ + pthread_t curthread; + int retval; + + _SEM_CHECK_VALIDITY(sem); + + curthread = _get_curthread(); + /* + * sem_post() is required to be safe to call from within signal + * handlers. Thus, we must defer signals. + */ + pthread_mutex_lock(&(*sem)->lock); + + /* GIANT_LOCK(curthread); */ + + (*sem)->count++; + if ((*sem)->nwaiters > 0) + pthread_cond_signal(&(*sem)->gtzero); + + /* GIANT_UNLOCK(curthread); */ + + pthread_mutex_unlock(&(*sem)->lock); + + retval = 0; + RETURN: + return retval; +} + +int +_sem_getvalue(sem_t *sem, int *sval) +{ + int retval; + + _SEM_CHECK_VALIDITY(sem); + + pthread_mutex_lock(&(*sem)->lock); + *sval = (int)(*sem)->count; + pthread_mutex_unlock(&(*sem)->lock); + + retval = 0; + RETURN: + return retval; +} |
