nuttx/libs/libc/pthread/pthread_keycreate.c

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/****************************************************************************
* libs/libc/pthread/pthread_keycreate.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <pthread.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/semaphore.h>
#include <nuttx/tls.h>
#if CONFIG_TLS_NELEM > 0
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pthread_key_create
*
* Description:
* This function creates a thread-specific data key visible to all threads
* in the system. Although the same key value may be used by different
* threads, the values bound to the key by pthread_setspecific() are
* maintained on a per-thread basis and persist for the life of the calling
* thread.
*
* Upon key creation, the value NULL will be associated with the new key
* in all active threads. Upon thread creation, the value NULL will be
* associated with all defined keys in the new thread.
*
* Input Parameters:
* key - A pointer to the key to create.
* destructor - An optional destructor() function that may be associated
* with each key that is invoked when a thread exits.
*
* Returned Value:
* If successful, the pthread_key_create() function will store the newly
* created key value at *key and return zero (OK). Otherwise, an error
* number will be returned to indicate the error:
*
* EAGAIN - The system lacked sufficient resources to create another
* thread-specific data key, or the system-imposed limit on
* the total number of keys pers process {PTHREAD_KEYS_MAX}
* has been exceeded
* ENOMEM - Insufficient memory exist to create the key.
*
****************************************************************************/
int pthread_key_create(FAR pthread_key_t *key,
CODE void (*destructor)(FAR void *))
{
FAR struct task_info_s *info = task_get_info();
int candidate;
int ret;
DEBUGASSERT(key != NULL);
DEBUGASSERT(info != NULL);
/* Search for an unused index. This is done in a critical section here to
* avoid concurrent modification of the group TLS index set.
*/
ret = _SEM_WAIT(&info->ta_sem);
if (ret < 0)
{
ret = _SEM_ERRNO(ret);
return ret;
}
ret = EAGAIN;
for (candidate = 0; candidate < CONFIG_TLS_NELEM; candidate++)
{
/* Is this candidate index available? */
tls_ndxset_t mask = (tls_ndxset_t)1 << candidate;
if ((info->ta_tlsset & mask) == 0)
{
/* Yes.. allocate the index and break out of the loop */
info->ta_tlsset |= mask;
info->ta_tlsdtor[candidate] = destructor;
*key = candidate;
ret = OK;
break;
}
}
_SEM_POST(&info->ta_sem);
return ret;
}
#endif /* CONFIG_TLS_NELEM */