incubator-nuttx/fs/mqueue/mq_unlink.c

167 lines
5.1 KiB
C

/****************************************************************************
* fs/mqueue/mq_unlink.c
*
* Copyright (C) 2007, 2009, 2014, 2017 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <stdio.h>
#include <mqueue.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/mqueue.h>
#include "inode/inode.h"
#include "mqueue/mqueue.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mq_unlink
*
* Description:
* This function removes the message queue named by "mq_name." If one
* or more tasks have the message queue open when mq_unlink() is called,
* removal of the message queue is postponed until all references to the
* message queue have been closed.
*
* Input Parameters:
* mq_name - Name of the message queue
*
* Returned Value:
* None
*
* Assumptions:
*
****************************************************************************/
int mq_unlink(FAR const char *mq_name)
{
FAR struct inode *inode;
struct inode_search_s desc;
char fullpath[MAX_MQUEUE_PATH];
int errcode;
int ret;
/* Get the full path to the message queue */
snprintf(fullpath, MAX_MQUEUE_PATH, CONFIG_FS_MQUEUE_MPATH "/%s", mq_name);
/* Get the inode for this message queue. */
SETUP_SEARCH(&desc, fullpath, false);
sched_lock();
ret = inode_find(&desc);
if (ret < 0)
{
/* There is no inode that includes in this path */
errcode = -ret;
goto errout_with_search;
}
/* Get the search results */
inode = desc.node;
DEBUGASSERT(inode != NULL);
/* Verify that what we found is, indeed, a message queue */
if (!INODE_IS_MQUEUE(inode))
{
errcode = ENXIO;
goto errout_with_inode;
}
/* Refuse to unlink the inode if it has children. I.e., if it is
* functioning as a directory and the directory is not empty.
*/
inode_semtake();
if (inode->i_child != NULL)
{
errcode = ENOTEMPTY;
goto errout_with_semaphore;
}
/* Remove the old inode from the tree. Because we hold a reference count
* on the inode, it will not be deleted now. This will set the
* FSNODEFLAG_DELETED bit in the inode flags.
*/
ret = inode_remove(fullpath);
/* inode_remove() should always fail with -EBUSY because we hae a reference
* on the inode. -EBUSY means that the inode was, indeed, unlinked but
* thatis could not be freed because there are references.
*/
DEBUGASSERT(ret >= 0 || ret == -EBUSY);
UNUSED(ret);
/* Now we do not release the reference count in the normal way (by calling
* inode release. Rather, we call mq_inode_release(). mq_inode_release
* will decrement the reference count on the inode. But it will also free
* the message queue if that reference count decrements to zero. Since we
* hold one reference, that can only occur if the message queue is not
* in-use.
*/
inode_semgive();
mq_inode_release(inode);
RELEASE_SEARCH(&desc);
sched_unlock();
return OK;
errout_with_semaphore:
inode_semgive();
errout_with_inode:
inode_release(inode);
errout_with_search:
RELEASE_SEARCH(&desc);
set_errno(errcode);
sched_unlock();
return ERROR;
}