1/* Linuxthreads - a simple clone()-based implementation of Posix */ 2/* threads for Linux. */ 3/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */ 4/* */ 5/* This program is free software; you can redistribute it and/or */ 6/* modify it under the terms of the GNU Library General Public License */ 7/* as published by the Free Software Foundation; either version 2 */ 8/* of the License, or (at your option) any later version. */ 9/* */ 10/* This program is distributed in the hope that it will be useful, */ 11/* but WITHOUT ANY WARRANTY; without even the implied warranty of */ 12/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */ 13/* GNU Library General Public License for more details. */ 14 15#ifndef _SEMAPHORE_H 16#define _SEMAPHORE_H 1 17 18#include <features.h> 19#include <sys/types.h> 20#ifdef __USE_XOPEN2K 21# define __need_timespec 22# include <time.h> 23#endif 24 25#ifndef _PTHREAD_DESCR_DEFINED 26/* Thread descriptors. Needed for `sem_t' definition. */ 27typedef struct _pthread_descr_struct *_pthread_descr; 28# define _PTHREAD_DESCR_DEFINED 29#endif 30 31/* System specific semaphore definition. */ 32typedef struct 33{ 34 struct _pthread_fastlock __sem_lock; 35 int __sem_value; 36 _pthread_descr __sem_waiting; 37} sem_t; 38 39 40 41/* Value returned if `sem_open' failed. */ 42#define SEM_FAILED ((sem_t *) 0) 43 44/* Maximum value the semaphore can have. */ 45#define SEM_VALUE_MAX ((int) ((~0u) >> 1)) 46 47 48__BEGIN_DECLS 49 50/* Initialize semaphore object SEM to VALUE. If PSHARED then share it 51 with other processes. */ 52extern int sem_init (sem_t *__sem, int __pshared, unsigned int __value) __THROW; 53 54/* Free resources associated with semaphore object SEM. */ 55extern int sem_destroy (sem_t *__sem) __THROW; 56 57/* Open a named semaphore NAME with open flags OFLAG. */ 58extern sem_t *sem_open (__const char *__name, int __oflag, ...) __THROW; 59 60/* Close descriptor for named semaphore SEM. */ 61extern int sem_close (sem_t *__sem) __THROW; 62 63/* Remove named semaphore NAME. */ 64extern int sem_unlink (__const char *__name) __THROW; 65 66/* Wait for SEM being posted. 67 68 This function is a cancellation point and therefore not marked with 69 __THROW. */ 70extern int sem_wait (sem_t *__sem); 71 72#ifdef __USE_XOPEN2K 73/* Similar to `sem_wait' but wait only until ABSTIME. 74 75 This function is a cancellation point and therefore not marked with 76 __THROW. */ 77extern int sem_timedwait (sem_t *__restrict __sem, 78 __const struct timespec *__restrict __abstime); 79#endif 80 81/* Test whether SEM is posted. */ 82extern int sem_trywait (sem_t *__sem) __THROW; 83 84/* Post SEM. */ 85extern int sem_post (sem_t *__sem) __THROW; 86 87/* Get current value of SEM and store it in *SVAL. */ 88extern int sem_getvalue (sem_t *__restrict __sem, int *__restrict __sval) 89 __THROW; 90 91 92__END_DECLS 93 94#endif /* semaphore.h */ 95