141 lines
4.8 KiB
C
141 lines
4.8 KiB
C
/****************************************************************************
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* sched/sem_unlink.c
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*
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* Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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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 <stdbool.h>
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#include <semaphore.h>
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#include <sched.h>
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#include <queue.h>
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#include "os_internal.h"
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#include "sem_internal.h"
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/****************************************************************************
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* Pre-processor 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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* Name: sem_unlink
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*
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* Description:
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* This function removes the semaphore named by the input parameter 'name.'
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* If the semaphore named by 'name' is currently referenced by other task,
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* the sem_unlink() will have no effect on the state of the semaphore. If
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* one or more processes have the semaphore open when sem_unlink() is
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* called, destruction of the semaphore will be postponed until all
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* references to the semaphore have been destroyed by calls of sem_close().
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*
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* Parameters:
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* name - Semaphore name
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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_unlink(FAR const char *name)
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{
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FAR nsem_t *psem;
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int ret = ERROR;
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/* Verify the input values */
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if (name)
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{
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sched_lock();
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/* Find the named semaphore */
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psem = sem_findnamed(name);
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/* Check if the semaphore was found */
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if (psem)
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{
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/* If the named semaphore was found and if there are no
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* connects to it, then deallocate it
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*/
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if (!psem->nconnect)
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{
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dq_rem((FAR dq_entry_t*)psem, &g_nsems);
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sched_kfree(psem);
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}
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/* If one or more process still has the semaphore open,
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* then just mark it as unlinked. The unlinked semaphore will
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* be deleted when the final process closes the semaphore.
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*/
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else
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{
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psem->unlinked = true;
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}
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ret = OK;
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}
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sched_unlock();
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}
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return ret;
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}
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