semaphore.h

Go to the documentation of this file.

/* Copyright (C) 2002-2022 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
 
   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.
 
   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.
 
   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */
 
#ifndef _SEMAPHORE_H
#define _SEMAPHORE_H    1
 
#include <time.h>
 
/* Definition for sem_t.  */
typedef struct
{
  int __lock;
  int __count;
  int __init;
  /* Threads currently blocked on this semaphore; see __ESBMC_sem_waiters. */
  unsigned int __waiters;
} sem_t;
 
/* Initialize semaphore object SEM to VALUE.  If PSHARED then share it
   with other processes.  */
extern int sem_init (sem_t *__sem, int __pshared, unsigned int __value);
 
/* Free resources associated with semaphore object SEM.  */
extern int sem_destroy (sem_t *__sem);
 
/* Open a named semaphore NAME with open flags OFLAG.  */
extern sem_t *sem_open (const char *__name, int __oflag, ...);
 
/* Close descriptor for named semaphore SEM.  */
extern int sem_close (sem_t *__sem);
 
/* Remove named semaphore NAME.  */
extern int sem_unlink (const char *__name);
 
/* Wait for SEM being posted.
 
   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern int sem_wait (sem_t *__sem);
 
#ifdef __USE_XOPEN2K
/* Similar to `sem_wait' but wait only until ABSTIME.
 
   This function is a cancellation point and therefore not marked with
   __THROW.  */
# ifndef __USE_TIME_BITS64
extern int sem_timedwait (sem_t *__restrict __sem,
              const struct timespec *__restrict __abstime);
# else
#  ifdef __REDIRECT
extern int __REDIRECT (sem_timedwait,
                       (sem_t *__restrict __sem,
                        const struct timespec *__restrict __abstime),
                        __sem_timedwait64);
#  else
#   define sem_timedwait __sem_timedwait64
#  endif
# endif
#endif
 
#ifdef __USE_GNU
# ifndef __USE_TIME_BITS64
extern int sem_clockwait (sem_t *__restrict __sem,
              clockid_t clock,
              const struct timespec *__restrict __abstime);
# else
#  ifdef __REDIRECT
extern int __REDIRECT (sem_clockwait,
                       (sem_t *__restrict __sem,
                        clockid_t clock,
                        const struct timespec *__restrict __abstime),
                        __sem_clockwait64);
#  else
#   define sem_clockwait __sem_clockwait64
#  endif
# endif
#endif
 
/* Test whether SEM is posted.  */
extern int sem_trywait (sem_t *__sem);
 
/* Post SEM.  */
extern int sem_post (sem_t *__sem);
 
/* Get current value of SEM and store it in *SVAL.  */
extern int sem_getvalue (sem_t *__restrict __sem, int *__restrict __sval);
 
#endif  /* semaphore.h */