153 lines
5.3 KiB
C
153 lines
5.3 KiB
C
/****************************************************************************
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* fs/semaphore/sem_close.c
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*
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* Copyright (C) 2014 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 <semaphore.h>
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#include <sched.h>
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#include <errno.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/semaphore.h>
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#include <nuttx/fs/fs.h>
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#include "inode/inode.h"
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#ifdef CONFIG_FS_NAMED_SEMAPHORES
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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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* Public Data
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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_close
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*
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* Description:
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* This function is called to indicate that the calling task is finished
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* with the specified named semaphore, 'sem'. The sem_close() deallocates
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* any system resources allocated by the system for this named semaphore.
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*
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* If the semaphore has not been removed with a call to sem_unlink(), then
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* sem_close() has no effect on the named semaphore. However, when the
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* named semaphore has been fully unlinked, the semaphore will vanish when
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* the last task closes it.
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*
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* Parameters:
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* sem - semaphore descriptor
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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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* - Care must be taken to avoid risking the deletion of a semaphore that
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* another calling task has already locked.
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* - sem_close must not be called for an un-named semaphore
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*
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****************************************************************************/
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int sem_close(FAR sem_t *sem)
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{
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FAR struct nsem_inode_s *nsem;
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struct inode *inode ;
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DEBUGASSERT(sem);
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/* Upcast to get back to out internal representation */
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nsem = (FAR struct nsem_inode_s *)sem;
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DEBUGASSERT(nsem->ns_inode);
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inode = nsem->ns_inode;
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/* Decrement the reference count on the inode */
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inode_semtake();
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if (inode->i_crefs > 0)
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{
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inode->i_crefs--;
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}
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/* If the semaphore was previously unlinked and the reference count has
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* decremented to zero, then release the semaphore and delete the inode
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* now.
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*/
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if (inode->i_crefs <= 0 && (inode->i_flags & FSNODEFLAG_DELETED) != 0)
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{
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/* Destroy the semaphore and free the container */
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sem_destroy(&nsem->ns_sem);
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group_free(NULL, nsem);
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/* Release and free the inode container. If it has been properly
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* unlinked, then the peer pointer should be NULL.
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*/
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inode_semgive();
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DEBUGASSERT(inode->i_peer == NULL);
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inode_free(inode);
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return OK;
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}
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inode_semgive();
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return OK;
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}
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#endif /* CONFIG_FS_NAMED_SEMAPHORES */
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