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lh9ed821d2023-04-07 01:36:19 -07001/* 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 */