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2000-02-22 Ulrich Drepper <drepper@redhat.com> * semaphore.h (SEM_FAILED): Use 0 not NULL.
81 lines
2.6 KiB
C
81 lines
2.6 KiB
C
/* Linuxthreads - a simple clone()-based implementation of Posix */
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/* threads for Linux. */
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/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
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/* */
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/* This program is free software; you can redistribute it and/or */
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/* modify it under the terms of the GNU Library General Public License */
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/* as published by the Free Software Foundation; either version 2 */
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/* of the License, or (at your option) any later version. */
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/* */
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/* This program is distributed in the hope that it will be useful, */
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/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
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/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
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/* GNU Library General Public License for more details. */
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#ifndef _SEMAPHORE_H
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#define _SEMAPHORE_H 1
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#include <features.h>
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#include <sys/types.h>
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#ifndef _PTHREAD_DESCR_DEFINED
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/* Thread descriptors. Needed for `sem_t' definition. */
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typedef struct _pthread_descr_struct *_pthread_descr;
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# define _PTHREAD_DESCR_DEFINED
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#endif
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/* System specific semaphore definition. */
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typedef struct
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{
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struct
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{
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long int status;
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int spinlock;
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} __sem_lock;
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int __sem_value;
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_pthread_descr __sem_waiting;
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} sem_t;
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/* Value returned if `sem_open' failed. */
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#define SEM_FAILED ((sem_t *) 0)
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/* Maximum value the semaphore can have. */
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#define SEM_VALUE_MAX ((int) ((~0u) >> 1))
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__BEGIN_DECLS
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/* Initialize semaphore object SEM to VALUE. If PSHARED then share it
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with other processes. */
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extern int sem_init (sem_t *__sem, int __pshared, unsigned int __value) __THROW;
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/* Free resources associated with semaphore object SEM. */
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extern int sem_destroy (sem_t *__sem) __THROW;
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/* Open a named semaphore NAME with open flaot OFLAG. */
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extern sem_t *sem_open (__const char *__name, int __oflag, ...) __THROW;
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/* Close descriptor for named semaphore SEM. */
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extern int sem_close (sem_t *__sem) __THROW;
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/* Remove named semaphore NAME. */
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extern int sem_unlink (__const char *__name) __THROW;
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/* Wait for SEM being posted. */
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extern int sem_wait (sem_t *__sem) __THROW;
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/* Test whether SEM is posted. */
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extern int sem_trywait (sem_t *__sem) __THROW;
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/* Post SEM. */
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extern int sem_post (sem_t *__sem) __THROW;
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/* Get current value of SEM and store it in *SVAL. */
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extern int sem_getvalue (sem_t *__sem, int *__sval) __THROW;
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__END_DECLS
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#endif /* semaphore.h */
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