forked from Archive/PX4-Autopilot
127 lines
4.6 KiB
C
127 lines
4.6 KiB
C
/****************************************************************************
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* lib/semaphore/sem_destroy.c
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*
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* Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <semaphore.h>
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#include <errno.h>
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#include "sem_internal.h"
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/****************************************************************************
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* Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Type Declarations
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****************************************************************************/
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/****************************************************************************
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* Global Variables
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****************************************************************************/
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/****************************************************************************
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* Private Variables
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Function: sem_destroy
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*
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* Description:
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* This function is used to destroy the un-named semaphore indicated by
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* 'sem'. Only a semaphore that was created using sem_init() may be
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* destroyed using sem_destroy(); the effect of calling sem_destroy() with
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* a named semaphore is undefined. The effect of subsequent use of the
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* semaphore sem is undefined until sem is re-initialized by another call
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* to sem_init().
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*
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* The effect of destroying a semaphore upon which other processes are
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* currently blocked is undefined.
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*
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* Parameters:
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* sem - Semaphore to be destroyed.
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*
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* Return Value:
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* 0 (OK), or -1 (ERROR) if unsuccessful.
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*
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* Assumptions:
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*
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****************************************************************************/
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int sem_destroy (FAR sem_t *sem)
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{
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/* Assure a valid semaphore is specified */
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if (sem)
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{
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/* There is really no particular action that we need
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* take to destroy a semaphore. We will just reset
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* the count to some reasonable value (1) and release
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* ownership.
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*
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* Check if other threads are waiting on the semaphore.
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* In this case, the behavior is undefined. We will:
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* leave the count unchanged but still return OK.
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*/
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if (sem->semcount >= 0)
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{
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sem->semcount = 1;
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}
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/* Release holders of the semaphore */
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sem_destroyholder(sem);
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return OK;
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}
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else
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{
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errno = -EINVAL;
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return ERROR;
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}
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}
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