NetBSD-5.0.2/lib/libpthread/sem.c
/* $NetBSD: sem.c,v 1.20 2008/04/28 20:23:02 martin Exp $ */
/*-
* Copyright (c) 2003, 2006, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of Wasabi Systems, Inc, and by Andrew Doran.
*
* 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, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
/*
* 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.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: sem.c,v 1.20 2008/04/28 20:23:02 martin Exp $");
#include <sys/types.h>
#include <sys/ksem.h>
#include <sys/queue.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdarg.h>
#include "pthread.h"
#include "pthread_int.h"
struct _sem_st {
unsigned int usem_magic;
#define USEM_MAGIC 0x09fa4012
LIST_ENTRY(_sem_st) usem_list;
semid_t usem_semid; /* 0 -> user (non-shared) */
#define USEM_USER 0 /* assumes kernel does not use NULL */
sem_t *usem_identity;
/* Protects data below. */
pthread_mutex_t usem_interlock;
pthread_cond_t usem_cv;
unsigned int usem_count;
};
static int sem_alloc(unsigned int value, semid_t semid, sem_t *semp);
static void sem_free(sem_t sem);
static LIST_HEAD(, _sem_st) named_sems = LIST_HEAD_INITIALIZER(&named_sems);
static pthread_mutex_t named_sems_mtx = PTHREAD_MUTEX_INITIALIZER;
static void
sem_free(sem_t sem)
{
if (sem->usem_semid == USEM_USER) {
pthread_cond_destroy(&sem->usem_cv);
pthread_mutex_destroy(&sem->usem_interlock);
}
sem->usem_magic = 0;
free(sem);
}
static int
sem_alloc(unsigned int value, semid_t semid, sem_t *semp)
{
sem_t sem;
if (value > SEM_VALUE_MAX)
return (EINVAL);
if ((sem = malloc(sizeof(struct _sem_st))) == NULL)
return (ENOSPC);
sem->usem_magic = USEM_MAGIC;
pthread_mutex_init(&sem->usem_interlock, NULL);
pthread_cond_init(&sem->usem_cv, NULL);
sem->usem_count = value;
sem->usem_semid = semid;
*semp = sem;
return (0);
}
int
sem_init(sem_t *sem, int pshared, unsigned int value)
{
semid_t semid;
int error;
semid = USEM_USER;
if (pshared && _ksem_init(value, &semid) == -1)
return (-1);
if ((error = sem_alloc(value, semid, sem)) != 0) {
if (semid != USEM_USER)
_ksem_destroy(semid);
errno = error;
return (-1);
}
return (0);
}
int
sem_destroy(sem_t *sem)
{
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
if ((*sem)->usem_semid != USEM_USER) {
if (_ksem_destroy((*sem)->usem_semid))
return (-1);
} else {
pthread_mutex_lock(&(*sem)->usem_interlock);
if (!PTQ_EMPTY(&(*sem)->usem_cv.ptc_waiters)) {
pthread_mutex_unlock(&(*sem)->usem_interlock);
errno = EBUSY;
return (-1);
}
pthread_mutex_unlock(&(*sem)->usem_interlock);
}
sem_free(*sem);
return (0);
}
sem_t *
sem_open(const char *name, int oflag, ...)
{
sem_t *sem, s;
semid_t semid;
mode_t mode;
unsigned int value;
int error;
va_list ap;
mode = 0;
value = 0;
if (oflag & O_CREAT) {
va_start(ap, oflag);
mode = va_arg(ap, int);
value = va_arg(ap, unsigned int);
va_end(ap);
}
/*
* We can be lazy and let the kernel handle the oflag,
* we'll just merge duplicate IDs into our list.
*/
if (_ksem_open(name, oflag, mode, value, &semid) == -1)
return (SEM_FAILED);
/*
* Search for a duplicate ID, we must return the same sem_t *
* if we locate one.
*/
pthread_mutex_lock(&named_sems_mtx);
LIST_FOREACH(s, &named_sems, usem_list) {
if (s->usem_semid == semid) {
pthread_mutex_unlock(&named_sems_mtx);
return (s->usem_identity);
}
}
if ((sem = malloc(sizeof(*sem))) == NULL) {
error = ENOSPC;
goto bad;
}
if ((error = sem_alloc(value, semid, sem)) != 0)
goto bad;
LIST_INSERT_HEAD(&named_sems, *sem, usem_list);
(*sem)->usem_identity = sem;
pthread_mutex_unlock(&named_sems_mtx);
return (sem);
bad:
pthread_mutex_unlock(&named_sems_mtx);
_ksem_close(semid);
if (sem != NULL) {
if (*sem != NULL)
sem_free(*sem);
free(sem);
}
errno = error;
return (SEM_FAILED);
}
int
sem_close(sem_t *sem)
{
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
if ((*sem)->usem_semid == USEM_USER) {
errno = EINVAL;
return (-1);
}
pthread_mutex_lock(&named_sems_mtx);
if (_ksem_close((*sem)->usem_semid) == -1) {
pthread_mutex_unlock(&named_sems_mtx);
return (-1);
}
LIST_REMOVE((*sem), usem_list);
pthread_mutex_unlock(&named_sems_mtx);
sem_free(*sem);
free(sem);
return (0);
}
int
sem_unlink(const char *name)
{
return (_ksem_unlink(name));
}
int
sem_wait(sem_t *sem)
{
pthread_t self;
extern int pthread__started;
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
self = pthread__self();
if ((*sem)->usem_semid != USEM_USER) {
pthread__testcancel(self);
return (_ksem_wait((*sem)->usem_semid));
}
if (pthread__started == 0) {
sigset_t set, oset;
sigfillset(&set);
(void) sigprocmask(SIG_SETMASK, &set, &oset);
for (;;) {
if ((*sem)->usem_count > 0) {
break;
}
(void) sigsuspend(&oset);
}
(*sem)->usem_count--;
(void) sigprocmask(SIG_SETMASK, &oset, NULL);
return 0;
}
pthread_mutex_lock(&(*sem)->usem_interlock);
for (;;) {
if (self->pt_cancel) {
pthread_mutex_unlock(&(*sem)->usem_interlock);
pthread__cancelled();
}
if ((*sem)->usem_count > 0)
break;
(void)pthread_cond_wait(&(*sem)->usem_cv,
&(*sem)->usem_interlock);
}
(*sem)->usem_count--;
pthread_mutex_unlock(&(*sem)->usem_interlock);
return (0);
}
int
sem_trywait(sem_t *sem)
{
extern int pthread__started;
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
if ((*sem)->usem_semid != USEM_USER)
return (_ksem_trywait((*sem)->usem_semid));
if (pthread__started == 0) {
sigset_t set, oset;
int rv = 0;
sigfillset(&set);
(void) sigprocmask(SIG_SETMASK, &set, &oset);
if ((*sem)->usem_count > 0) {
(*sem)->usem_count--;
} else {
errno = EAGAIN;
rv = -1;
}
(void) sigprocmask(SIG_SETMASK, &oset, NULL);
return rv;
}
pthread_mutex_lock(&(*sem)->usem_interlock);
if ((*sem)->usem_count == 0) {
pthread_mutex_unlock(&(*sem)->usem_interlock);
errno = EAGAIN;
return (-1);
}
(*sem)->usem_count--;
pthread_mutex_unlock(&(*sem)->usem_interlock);
return (0);
}
int
sem_post(sem_t *sem)
{
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
if ((*sem)->usem_semid != USEM_USER)
return (_ksem_post((*sem)->usem_semid));
pthread_mutex_lock(&(*sem)->usem_interlock);
(*sem)->usem_count++;
pthread_cond_signal(&(*sem)->usem_cv);
pthread_mutex_unlock(&(*sem)->usem_interlock);
return (0);
}
int
sem_getvalue(sem_t * __restrict sem, int * __restrict sval)
{
#ifdef ERRORCHECK
if (sem == NULL || *sem == NULL || (*sem)->usem_magic != USEM_MAGIC) {
errno = EINVAL;
return (-1);
}
#endif
if ((*sem)->usem_semid != USEM_USER)
return (_ksem_getvalue((*sem)->usem_semid, sval));
pthread_mutex_lock(&(*sem)->usem_interlock);
*sval = (int) (*sem)->usem_count;
pthread_mutex_unlock(&(*sem)->usem_interlock);
return (0);
}