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. */ 27 typedef struct pthread *_pthread_descr; 28 # define _PTHREAD_DESCR_DEFINED 29 #endif 30 31 /* System specific semaphore definition. */ 32 typedef 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 (2147483647) 46 47 48 __BEGIN_DECLS 49 50 /* Initialize semaphore object SEM to VALUE. If PSHARED then share it 51 with other processes. */ 52 extern int sem_init (sem_t *__sem, int __pshared, unsigned int __value) __THROW; 53 54 /* Free resources associated with semaphore object SEM. */ 55 extern int sem_destroy (sem_t *__sem) __THROW; 56 57 /* Open a named semaphore NAME with open flags OFLAG. */ 58 extern sem_t *sem_open (__const char *__name, int __oflag, ...) __THROW; 59 60 /* Close descriptor for named semaphore SEM. */ 61 extern int sem_close (sem_t *__sem) __THROW; 62 63 /* Remove named semaphore NAME. */ 64 extern 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. */ 70 extern 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. */ 77 extern int sem_timedwait (sem_t *__restrict __sem, 78 __const struct timespec *__restrict __abstime); 79 #endif 80 81 /* Test whether SEM is posted. */ 82 extern int sem_trywait (sem_t *__sem) __THROW; 83 84 /* Post SEM. */ 85 extern int sem_post (sem_t *__sem) __THROW; 86 87 /* Get current value of SEM and store it in *SVAL. */ 88 extern int sem_getvalue (sem_t *__restrict __sem, int *__restrict __sval) 89 __THROW; 90 91 92 __END_DECLS 93 94 #endif /* semaphore.h */ 95