161 lines
4.6 KiB
C
161 lines
4.6 KiB
C
/****************************************************************************
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* fs/semaphore/sem_unlink.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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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 <stdio.h>
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#include <sched.h>
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#include <queue.h>
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#include <errno.h>
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#include <assert.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/semaphore.h>
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#include "inode/inode.h"
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#include "semaphore/semaphore.h"
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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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* Input Parameters:
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* name - Semaphore name
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*
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* Returned 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 struct inode *inode;
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struct inode_search_s desc;
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char fullpath[MAX_SEMPATH];
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int errcode;
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int ret;
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/* Get the full path to the semaphore */
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snprintf(fullpath, MAX_SEMPATH, CONFIG_FS_NAMED_SEMPATH "/%s", name);
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/* Get the inode for this semaphore. */
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SETUP_SEARCH(&desc, fullpath, false);
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sched_lock();
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ret = inode_find(&desc);
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if (ret < 0)
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{
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/* There is no inode that includes in this path */
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errcode = -ret;
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goto errout_with_search;
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}
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/* Get the search results */
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inode = desc.node;
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DEBUGASSERT(inode != NULL);
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/* Verify that what we found is, indeed, a semaphore */
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if (!INODE_IS_NAMEDSEM(inode))
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{
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errcode = ENXIO;
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goto errout_with_inode;
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}
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/* Refuse to unlink the inode if it has children. I.e., if it is
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* functioning as a directory and the directory is not empty.
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*/
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ret = inode_semtake();
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if (ret < 0)
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{
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errcode = -ret;
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goto errout_with_inode;
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}
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if (inode->i_child != NULL)
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{
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errcode = ENOTEMPTY;
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goto errout_with_semaphore;
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}
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/* Remove the old inode from the tree. Because we hold a reference count
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* on the inode, it will not be deleted now. This will set the
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* FSNODEFLAG_DELETED bit in the inode flags.
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*/
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ret = inode_remove(fullpath);
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/* inode_remove() should always fail with -EBUSY because we hae a reference
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* on the inode. -EBUSY means that the inode was, indeed, unlinked but
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* thatis could not be freed because there are references.
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*/
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DEBUGASSERT(ret >= 0 || ret == -EBUSY);
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UNUSED(ret);
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/* Now we do not release the reference count in the normal way (by calling
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* inode release. Rather, we call sem_close(). sem_close will decrement
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* the reference count on the inode. But it will also free the semaphore
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* if that reference count decrements to zero. Since we hold one
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* reference, that can only occur if the semaphore is not in-use.
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*/
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inode_semgive();
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ret = sem_close((FAR sem_t *)inode->u.i_nsem);
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RELEASE_SEARCH(&desc);
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sched_unlock();
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return ret;
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errout_with_semaphore:
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inode_semgive();
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errout_with_inode:
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inode_release(inode);
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errout_with_search:
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RELEASE_SEARCH(&desc);
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set_errno(errcode);
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sched_unlock();
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return ERROR;
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}
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