patacongo commented on a change in pull request #3170: URL: https://github.com/apache/incubator-nuttx/pull/3170#discussion_r601520818
########## File path: libs/libc/unistd/lib_getoptvars.c ########## @@ -0,0 +1,166 @@ +/**************************************************************************** + * libs/libc/unistd/lib_getoptvars.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 <unistd.h> +#include <pthread.h> + +#include "unistd.h" +#include "libc.h" + +/**************************************************************************** + * Pre-processor Definitions + ****************************************************************************/ + +#define INVALID_KEY CONFIG_TLS_NELEM +#define VALID_KEY(key) ((key) >= 0 && key < CONFIG_TLS_NELEM) + +/* Configuration. Currently no thread-specific data destructors. */ + +#undef HAVE_DESTRUCTOR +#define HAVE_CLEANUP 1 +#define HAVE_TLSVARS 1 + +/* Check if we have some way to avoid a memory leak */ + +#if defined(CONFIG_DISABLE_PTHREAD) || !defined(CONFIG_PTHREAD_CLEANUP) +# undef HAVE_CLEANUP +#endif + +/* Don't use TLS if we cannot avoid the memory leak or if TLS is disabled */ + +#if (!defined(HAVE_DESTRUCTOR) && !defined(HAVE_CLEANUP)) || \ + CONFIG_TLS_NELEM == 0 +# undef HAVE_TLSVARS +#endif + +/**************************************************************************** + * Private Data + ****************************************************************************/ + +#ifdef HAVE_TLSVARS +static pthread_key_t g_getopt_key = (pthread_key_t)INVALID_KEY; +static pthread_mutex_t g_getopt_mutex = PTHREAD_MUTEX_INITIALIZER; + +#else +/* Fallback to avoid memory leak when there is no destructor and no cleanup + * or when there is no TLS. + */ + +FAR struct getopt_s g_getopt_vars = +{ + NULL, + 0, + 1, + '?' +}; +#endif + +/**************************************************************************** + * Private Functions + ****************************************************************************/ + +#ifdef HAVE_TLSVARS +void _getopt_destructor(FAR void *getoptvars) +{ + lib_free(getoptvars); +} +#endif + +/**************************************************************************** + * Public Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: getoptvars + * + * Description: + * Returns a pointer to to the thread-specific getopt() data. + * + ****************************************************************************/ + +FAR struct getopt_s *getoptvars(void) +{ +#ifdef HAVE_TLSVARS + FAR struct getopt_s *go; + int ret; + + ret = pthread_mutex_lock(&g_getopt_mutex); + DEBUGASSERT(ret == OK); + UNUSED(ret); + + /* Check if a key has been assigned */ + + if (!VALID_KEY(g_getopt_key)) + { + ret = pthread_key_create(&g_getopt_key, _getopt_destructor); + DEBUGASSERT(ret == OK); + UNUSED(ret); + } + + /* Get the structure of getopt() variables using the key. */ + + go = (FAR struct getopt_s *)pthread_getspecific(g_getopt_key); + if (go == NULL) + { + /* The instance has not yet been created. Allocate getopt() + * it now. + */ + + go = (FAR struct getopt_s *)lib_malloc(sizeof(struct getopt_s)); Review comment: > How can the exit path find the callback and then call it? It can't. pthread data destructors have never been implemented. @antmerlino was planning on doing this on https://github.com/apache/incubator-nuttx/tree/feature/pthread-user, but that effort lost focus. This is handled in libs/libc/unistd/lib_getoptvars.c. Basically, it uses pthread_cleanup() instead of the data destructor. That works just fine in this case: ``` 42 #undef HAVE_DESTRUCTOR 91 #ifdef HAVE_TLSVARS 92 void _getopt_destructor(FAR void *getoptvars) 93 { 94 lib_free(getoptvars); 95 } 96 #endif 124 ret = pthread_key_create(&g_getopt_key, _getopt_destructor); 155 #if !defined(HAVE_DESTRUCTOR) && defined(CONFIG_PTHREAD_CLEANUP) 156 if (ret == OK) 157 { 158 /* Free the thread-specific data when the thread exits */ 159 160 pthread_cleanup_push(_getopt_destructor, go); 161 } 162 #endif ``` The second parameter to pthread_key_create() at line 96 does nothing as you note. That actually deallocation is setup by pthread_cleanup_push() at line 160 when the pthread exits. That is sufficient in this case -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
