crypto/ex_data.c - third_party/openssl - Git at Google

 /*
  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the OpenSSL license (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 #include "internal/cryptlib_int.h"
 #include "internal/thread_once.h"
 #include <openssl/lhash.h>

 /*
  * Each structure type (sometimes called a class), that supports
  * exdata has a stack of callbacks for each instance.
  */
 struct ex_callback_st {
     long argl;                  /* Arbitrary long */
     void *argp;                 /* Arbitrary void * */
     CRYPTO_EX_new *new_func;
     CRYPTO_EX_free *free_func;
     CRYPTO_EX_dup *dup_func;
 };

 /*
  * The state for each class.  This could just be a typedef, but
  * a structure allows future changes.
  */
 typedef struct ex_callbacks_st {
     STACK_OF(EX_CALLBACK) *meth;
 } EX_CALLBACKS;

 static EX_CALLBACKS ex_data[CRYPTO_EX_INDEX__COUNT];

 static CRYPTO_RWLOCK *ex_data_lock = NULL;
 static CRYPTO_ONCE ex_data_init = CRYPTO_ONCE_STATIC_INIT;

 DEFINE_RUN_ONCE_STATIC(do_ex_data_init)
 {
     OPENSSL_init_crypto(0, NULL);
     ex_data_lock = CRYPTO_THREAD_lock_new();
     return ex_data_lock != NULL;
 }

 /*
  * Return the EX_CALLBACKS from the |ex_data| array that corresponds to
  * a given class.  On success, *holds the lock.*
  */
 static EX_CALLBACKS *get_and_lock(int class_index)
 {
     EX_CALLBACKS *ip;

     if (class_index < 0 || class_index >= CRYPTO_EX_INDEX__COUNT) {
         CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_PASSED_INVALID_ARGUMENT);
         return NULL;
     }

     if (!RUN_ONCE(&ex_data_init, do_ex_data_init)) {
         CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_MALLOC_FAILURE);
         return NULL;
     }

     if (ex_data_lock == NULL) {
         /*
          * This can happen in normal operation when using CRYPTO_mem_leaks().
          * The CRYPTO_mem_leaks() function calls OPENSSL_cleanup() which cleans
          * up the locks. Subsequently the BIO that CRYPTO_mem_leaks() uses gets
          * freed, which also attempts to free the ex_data. However
          * CRYPTO_mem_leaks() ensures that the ex_data is freed early (i.e.
          * before OPENSSL_cleanup() is called), so if we get here we can safely
          * ignore this operation. We just treat it as an error.
          */
          return NULL;
     }

     ip = &ex_data[class_index];
     CRYPTO_THREAD_write_lock(ex_data_lock);
     return ip;
 }

 static void cleanup_cb(EX_CALLBACK *funcs)
 {
     OPENSSL_free(funcs);
 }

 /*
  * Release all "ex_data" state to prevent memory leaks. This can't be made
  * thread-safe without overhauling a lot of stuff, and shouldn't really be
  * called under potential race-conditions anyway (it's for program shutdown
  * after all).
  */
 void crypto_cleanup_all_ex_data_int(void)
 {
     int i;

     for (i = 0; i < CRYPTO_EX_INDEX__COUNT; ++i) {
         EX_CALLBACKS *ip = &ex_data[i];

         sk_EX_CALLBACK_pop_free(ip->meth, cleanup_cb);
         ip->meth = NULL;
     }

     CRYPTO_THREAD_lock_free(ex_data_lock);
     ex_data_lock = NULL;
 }


 /*
  * Unregister a new index by replacing the callbacks with no-ops.
  * Any in-use instances are leaked.
  */
 static void dummy_new(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
                      long argl, void *argp)
 {
 }

 static void dummy_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad, int idx,
                        long argl, void *argp)
 {
 }

 static int dummy_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
                      void *from_d, int idx,
                      long argl, void *argp)
 {
     return 1;
 }

 int CRYPTO_free_ex_index(int class_index, int idx)
 {
     EX_CALLBACKS *ip = get_and_lock(class_index);
     EX_CALLBACK *a;
     int toret = 0;

     if (ip == NULL)
         return 0;
     if (idx < 0 || idx >= sk_EX_CALLBACK_num(ip->meth))
         goto err;
     a = sk_EX_CALLBACK_value(ip->meth, idx);
     if (a == NULL)
         goto err;
     a->new_func = dummy_new;
     a->dup_func = dummy_dup;
     a->free_func = dummy_free;
     toret = 1;
 err:
     CRYPTO_THREAD_unlock(ex_data_lock);
     return toret;
 }

 /*
  * Register a new index.
  */
 int CRYPTO_get_ex_new_index(int class_index, long argl, void *argp,
                             CRYPTO_EX_new *new_func, CRYPTO_EX_dup *dup_func,
                             CRYPTO_EX_free *free_func)
 {
     int toret = -1;
     EX_CALLBACK *a;
     EX_CALLBACKS *ip = get_and_lock(class_index);

     if (ip == NULL)
         return -1;

     if (ip->meth == NULL) {
         ip->meth = sk_EX_CALLBACK_new_null();
         /* We push an initial value on the stack because the SSL
          * "app_data" routines use ex_data index zero.  See RT 3710. */
         if (ip->meth == NULL
             || !sk_EX_CALLBACK_push(ip->meth, NULL)) {
             CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
             goto err;
         }
     }

     a = (EX_CALLBACK *)OPENSSL_malloc(sizeof(*a));
     if (a == NULL) {
         CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
         goto err;
     }
     a->argl = argl;
     a->argp = argp;
     a->new_func = new_func;
     a->dup_func = dup_func;
     a->free_func = free_func;

     if (!sk_EX_CALLBACK_push(ip->meth, NULL)) {
         CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
         OPENSSL_free(a);
         goto err;
     }
     toret = sk_EX_CALLBACK_num(ip->meth) - 1;
     (void)sk_EX_CALLBACK_set(ip->meth, toret, a);

  err:
     CRYPTO_THREAD_unlock(ex_data_lock);
     return toret;
 }

 /*
  * Initialise a new CRYPTO_EX_DATA for use in a particular class - including
  * calling new() callbacks for each index in the class used by this variable
  * Thread-safe by copying a class's array of "EX_CALLBACK" entries
  * in the lock, then using them outside the lock. Note this only applies
  * to the global "ex_data" state (ie. class definitions), not 'ad' itself.
  */
 int CRYPTO_new_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
 {
     int mx, i;
     void *ptr;
     EX_CALLBACK **storage = NULL;
     EX_CALLBACK *stack[10];
     EX_CALLBACKS *ip = get_and_lock(class_index);

     if (ip == NULL)
         return 0;

     ad->sk = NULL;

     mx = sk_EX_CALLBACK_num(ip->meth);
     if (mx > 0) {
         if (mx < (int)OSSL_NELEM(stack))
             storage = stack;
         else
             storage = OPENSSL_malloc(sizeof(*storage) * mx);
         if (storage != NULL)
             for (i = 0; i < mx; i++)
                 storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
     }
     CRYPTO_THREAD_unlock(ex_data_lock);

     if (mx > 0 && storage == NULL) {
         CRYPTOerr(CRYPTO_F_CRYPTO_NEW_EX_DATA, ERR_R_MALLOC_FAILURE);
         return 0;
     }
     for (i = 0; i < mx; i++) {
         if (storage[i] && storage[i]->new_func) {
             ptr = CRYPTO_get_ex_data(ad, i);
             storage[i]->new_func(obj, ptr, ad, i,
                                  storage[i]->argl, storage[i]->argp);
         }
     }
     if (storage != stack)
         OPENSSL_free(storage);
     return 1;
 }

 /*
  * Duplicate a CRYPTO_EX_DATA variable - including calling dup() callbacks
  * for each index in the class used by this variable
  */
 int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
                        const CRYPTO_EX_DATA *from)
 {
     int mx, j, i;
     void *ptr;
     EX_CALLBACK *stack[10];
     EX_CALLBACK **storage = NULL;
     EX_CALLBACKS *ip;
     int toret = 0;

     if (from->sk == NULL)
         /* Nothing to copy over */
         return 1;
     if ((ip = get_and_lock(class_index)) == NULL)
         return 0;

     mx = sk_EX_CALLBACK_num(ip->meth);
     j = sk_void_num(from->sk);
     if (j < mx)
         mx = j;
     if (mx > 0) {
         if (mx < (int)OSSL_NELEM(stack))
             storage = stack;
         else
             storage = OPENSSL_malloc(sizeof(*storage) * mx);
         if (storage != NULL)
             for (i = 0; i < mx; i++)
                 storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
     }
     CRYPTO_THREAD_unlock(ex_data_lock);

     if (mx == 0)
         return 1;
     if (storage == NULL) {
         CRYPTOerr(CRYPTO_F_CRYPTO_DUP_EX_DATA, ERR_R_MALLOC_FAILURE);
         return 0;
     }
     /*
      * Make sure the ex_data stack is at least |mx| elements long to avoid
      * issues in the for loop that follows; so go get the |mx|'th element
      * (if it does not exist CRYPTO_get_ex_data() returns NULL), and assign
      * to itself. This is normally a no-op; but ensures the stack is the
      * proper size
      */
     if (!CRYPTO_set_ex_data(to, mx - 1, CRYPTO_get_ex_data(to, mx - 1)))
         goto err;

     for (i = 0; i < mx; i++) {
         ptr = CRYPTO_get_ex_data(from, i);
         if (storage[i] && storage[i]->dup_func)
             if (!storage[i]->dup_func(to, from, &ptr, i,
                                       storage[i]->argl, storage[i]->argp))
                 goto err;
         CRYPTO_set_ex_data(to, i, ptr);
     }
     toret = 1;
  err:
     if (storage != stack)
         OPENSSL_free(storage);
     return toret;
 }


 /*
  * Cleanup a CRYPTO_EX_DATA variable - including calling free() callbacks for
  * each index in the class used by this variable
  */
 void CRYPTO_free_ex_data(int class_index, void *obj, CRYPTO_EX_DATA *ad)
 {
     int mx, i;
     EX_CALLBACKS *ip;
     void *ptr;
     EX_CALLBACK *f;
     EX_CALLBACK *stack[10];
     EX_CALLBACK **storage = NULL;

     if ((ip = get_and_lock(class_index)) == NULL)
         goto err;

     mx = sk_EX_CALLBACK_num(ip->meth);
     if (mx > 0) {
         if (mx < (int)OSSL_NELEM(stack))
             storage = stack;
         else
             storage = OPENSSL_malloc(sizeof(*storage) * mx);
         if (storage != NULL)
             for (i = 0; i < mx; i++)
                 storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
     }
     CRYPTO_THREAD_unlock(ex_data_lock);

     for (i = 0; i < mx; i++) {
         if (storage != NULL)
             f = storage[i];
         else {
             CRYPTO_THREAD_write_lock(ex_data_lock);
             f = sk_EX_CALLBACK_value(ip->meth, i);
             CRYPTO_THREAD_unlock(ex_data_lock);
         }
         if (f != NULL && f->free_func != NULL) {
             ptr = CRYPTO_get_ex_data(ad, i);
             f->free_func(obj, ptr, ad, i, f->argl, f->argp);
         }
     }

     if (storage != stack)
         OPENSSL_free(storage);
  err:
     sk_void_free(ad->sk);
     ad->sk = NULL;
 }

 /*
  * For a given CRYPTO_EX_DATA variable, set the value corresponding to a
  * particular index in the class used by this variable
  */
 int CRYPTO_set_ex_data(CRYPTO_EX_DATA *ad, int idx, void *val)
 {
     int i;

     if (ad->sk == NULL) {
         if ((ad->sk = sk_void_new_null()) == NULL) {
             CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
             return 0;
         }
     }

     for (i = sk_void_num(ad->sk); i <= idx; ++i) {
         if (!sk_void_push(ad->sk, NULL)) {
             CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
             return 0;
         }
     }
     sk_void_set(ad->sk, idx, val);
     return 1;
 }

 /*
  * For a given CRYPTO_EX_DATA_ variable, get the value corresponding to a
  * particular index in the class used by this variable
  */
 void *CRYPTO_get_ex_data(const CRYPTO_EX_DATA *ad, int idx)
 {
     if (ad->sk == NULL || idx >= sk_void_num(ad->sk))
         return NULL;
     return sk_void_value(ad->sk, idx);
 }
	/*
	* Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the OpenSSL license (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	#include "internal/cryptlib_int.h"
	#include "internal/thread_once.h"
	#include <openssl/lhash.h>

	/*
	* Each structure type (sometimes called a class), that supports
	* exdata has a stack of callbacks for each instance.
	*/
	struct ex_callback_st {
	long argl; /* Arbitrary long */
	void argp; / Arbitrary void * */
	CRYPTO_EX_new *new_func;
	CRYPTO_EX_free *free_func;
	CRYPTO_EX_dup *dup_func;
	};

	/*
	* The state for each class. This could just be a typedef, but
	* a structure allows future changes.
	*/
	typedef struct ex_callbacks_st {
	STACK_OF(EX_CALLBACK) *meth;
	} EX_CALLBACKS;

	static EX_CALLBACKS ex_data[CRYPTO_EX_INDEX__COUNT];

	static CRYPTO_RWLOCK *ex_data_lock = NULL;
	static CRYPTO_ONCE ex_data_init = CRYPTO_ONCE_STATIC_INIT;

	DEFINE_RUN_ONCE_STATIC(do_ex_data_init)
	{
	OPENSSL_init_crypto(0, NULL);
	ex_data_lock = CRYPTO_THREAD_lock_new();
	return ex_data_lock != NULL;
	}

	/*
	* Return the EX_CALLBACKS from the \|ex_data\| array that corresponds to
	* a given class. On success, holds the lock.
	*/
	static EX_CALLBACKS *get_and_lock(int class_index)
	{
	EX_CALLBACKS *ip;

	if (class_index < 0 \|\| class_index >= CRYPTO_EX_INDEX__COUNT) {
	CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_PASSED_INVALID_ARGUMENT);
	return NULL;
	}

	if (!RUN_ONCE(&ex_data_init, do_ex_data_init)) {
	CRYPTOerr(CRYPTO_F_GET_AND_LOCK, ERR_R_MALLOC_FAILURE);
	return NULL;
	}

	if (ex_data_lock == NULL) {
	/*
	* This can happen in normal operation when using CRYPTO_mem_leaks().
	* The CRYPTO_mem_leaks() function calls OPENSSL_cleanup() which cleans
	* up the locks. Subsequently the BIO that CRYPTO_mem_leaks() uses gets
	* freed, which also attempts to free the ex_data. However
	* CRYPTO_mem_leaks() ensures that the ex_data is freed early (i.e.
	* before OPENSSL_cleanup() is called), so if we get here we can safely
	* ignore this operation. We just treat it as an error.
	*/
	return NULL;
	}

	ip = &ex_data[class_index];
	CRYPTO_THREAD_write_lock(ex_data_lock);
	return ip;
	}

	static void cleanup_cb(EX_CALLBACK *funcs)
	{
	OPENSSL_free(funcs);
	}

	/*
	* Release all "ex_data" state to prevent memory leaks. This can't be made
	* thread-safe without overhauling a lot of stuff, and shouldn't really be
	* called under potential race-conditions anyway (it's for program shutdown
	* after all).
	*/
	void crypto_cleanup_all_ex_data_int(void)
	{
	int i;

	for (i = 0; i < CRYPTO_EX_INDEX__COUNT; ++i) {
	EX_CALLBACKS *ip = &ex_data[i];

	sk_EX_CALLBACK_pop_free(ip->meth, cleanup_cb);
	ip->meth = NULL;
	}

	CRYPTO_THREAD_lock_free(ex_data_lock);
	ex_data_lock = NULL;
	}


	/*
	* Unregister a new index by replacing the callbacks with no-ops.
	* Any in-use instances are leaked.
	*/
	static void dummy_new(void parent, void ptr, CRYPTO_EX_DATA *ad, int idx,
	long argl, void *argp)
	{
	}

	static void dummy_free(void parent, void ptr, CRYPTO_EX_DATA *ad, int idx,
	long argl, void *argp)
	{
	}

	static int dummy_dup(CRYPTO_EX_DATA to, const CRYPTO_EX_DATA from,
	void *from_d, int idx,
	long argl, void *argp)
	{
	return 1;
	}

	int CRYPTO_free_ex_index(int class_index, int idx)
	{
	EX_CALLBACKS *ip = get_and_lock(class_index);
	EX_CALLBACK *a;
	int toret = 0;

	if (ip == NULL)
	return 0;
	if (idx < 0 \|\| idx >= sk_EX_CALLBACK_num(ip->meth))
	goto err;
	a = sk_EX_CALLBACK_value(ip->meth, idx);
	if (a == NULL)
	goto err;
	a->new_func = dummy_new;
	a->dup_func = dummy_dup;
	a->free_func = dummy_free;
	toret = 1;
	err:
	CRYPTO_THREAD_unlock(ex_data_lock);
	return toret;
	}

	/*
	* Register a new index.
	*/
	int CRYPTO_get_ex_new_index(int class_index, long argl, void *argp,
	CRYPTO_EX_new new_func, CRYPTO_EX_dup dup_func,
	CRYPTO_EX_free *free_func)
	{
	int toret = -1;
	EX_CALLBACK *a;
	EX_CALLBACKS *ip = get_and_lock(class_index);

	if (ip == NULL)
	return -1;

	if (ip->meth == NULL) {
	ip->meth = sk_EX_CALLBACK_new_null();
	/* We push an initial value on the stack because the SSL
	* "app_data" routines use ex_data index zero. See RT 3710. */
	if (ip->meth == NULL
	\|\| !sk_EX_CALLBACK_push(ip->meth, NULL)) {
	CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
	goto err;
	}
	}

	a = (EX_CALLBACK )OPENSSL_malloc(sizeof(a));
	if (a == NULL) {
	CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
	goto err;
	}
	a->argl = argl;
	a->argp = argp;
	a->new_func = new_func;
	a->dup_func = dup_func;
	a->free_func = free_func;

	if (!sk_EX_CALLBACK_push(ip->meth, NULL)) {
	CRYPTOerr(CRYPTO_F_CRYPTO_GET_EX_NEW_INDEX, ERR_R_MALLOC_FAILURE);
	OPENSSL_free(a);
	goto err;
	}
	toret = sk_EX_CALLBACK_num(ip->meth) - 1;
	(void)sk_EX_CALLBACK_set(ip->meth, toret, a);

	err:
	CRYPTO_THREAD_unlock(ex_data_lock);
	return toret;
	}

	/*
	* Initialise a new CRYPTO_EX_DATA for use in a particular class - including
	* calling new() callbacks for each index in the class used by this variable
	* Thread-safe by copying a class's array of "EX_CALLBACK" entries
	* in the lock, then using them outside the lock. Note this only applies
	* to the global "ex_data" state (ie. class definitions), not 'ad' itself.
	*/
	int CRYPTO_new_ex_data(int class_index, void obj, CRYPTO_EX_DATA ad)
	{
	int mx, i;
	void *ptr;
	EX_CALLBACK **storage = NULL;
	EX_CALLBACK *stack[10];
	EX_CALLBACKS *ip = get_and_lock(class_index);

	if (ip == NULL)
	return 0;

	ad->sk = NULL;

	mx = sk_EX_CALLBACK_num(ip->meth);
	if (mx > 0) {
	if (mx < (int)OSSL_NELEM(stack))
	storage = stack;
	else
	storage = OPENSSL_malloc(sizeof(storage) mx);
	if (storage != NULL)
	for (i = 0; i < mx; i++)
	storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
	}
	CRYPTO_THREAD_unlock(ex_data_lock);

	if (mx > 0 && storage == NULL) {
	CRYPTOerr(CRYPTO_F_CRYPTO_NEW_EX_DATA, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	for (i = 0; i < mx; i++) {
	if (storage[i] && storage[i]->new_func) {
	ptr = CRYPTO_get_ex_data(ad, i);
	storage[i]->new_func(obj, ptr, ad, i,
	storage[i]->argl, storage[i]->argp);
	}
	}
	if (storage != stack)
	OPENSSL_free(storage);
	return 1;
	}

	/*
	* Duplicate a CRYPTO_EX_DATA variable - including calling dup() callbacks
	* for each index in the class used by this variable
	*/
	int CRYPTO_dup_ex_data(int class_index, CRYPTO_EX_DATA *to,
	const CRYPTO_EX_DATA *from)
	{
	int mx, j, i;
	void *ptr;
	EX_CALLBACK *stack[10];
	EX_CALLBACK **storage = NULL;
	EX_CALLBACKS *ip;
	int toret = 0;

	if (from->sk == NULL)
	/* Nothing to copy over */
	return 1;
	if ((ip = get_and_lock(class_index)) == NULL)
	return 0;

	mx = sk_EX_CALLBACK_num(ip->meth);
	j = sk_void_num(from->sk);
	if (j < mx)
	mx = j;
	if (mx > 0) {
	if (mx < (int)OSSL_NELEM(stack))
	storage = stack;
	else
	storage = OPENSSL_malloc(sizeof(storage) mx);
	if (storage != NULL)
	for (i = 0; i < mx; i++)
	storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
	}
	CRYPTO_THREAD_unlock(ex_data_lock);

	if (mx == 0)
	return 1;
	if (storage == NULL) {
	CRYPTOerr(CRYPTO_F_CRYPTO_DUP_EX_DATA, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	/*
	* Make sure the ex_data stack is at least \|mx\| elements long to avoid
	* issues in the for loop that follows; so go get the \|mx\|'th element
	* (if it does not exist CRYPTO_get_ex_data() returns NULL), and assign
	* to itself. This is normally a no-op; but ensures the stack is the
	* proper size
	*/
	if (!CRYPTO_set_ex_data(to, mx - 1, CRYPTO_get_ex_data(to, mx - 1)))
	goto err;

	for (i = 0; i < mx; i++) {
	ptr = CRYPTO_get_ex_data(from, i);
	if (storage[i] && storage[i]->dup_func)
	if (!storage[i]->dup_func(to, from, &ptr, i,
	storage[i]->argl, storage[i]->argp))
	goto err;
	CRYPTO_set_ex_data(to, i, ptr);
	}
	toret = 1;
	err:
	if (storage != stack)
	OPENSSL_free(storage);
	return toret;
	}


	/*
	* Cleanup a CRYPTO_EX_DATA variable - including calling free() callbacks for
	* each index in the class used by this variable
	*/
	void CRYPTO_free_ex_data(int class_index, void obj, CRYPTO_EX_DATA ad)
	{
	int mx, i;
	EX_CALLBACKS *ip;
	void *ptr;
	EX_CALLBACK *f;
	EX_CALLBACK *stack[10];
	EX_CALLBACK **storage = NULL;

	if ((ip = get_and_lock(class_index)) == NULL)
	goto err;

	mx = sk_EX_CALLBACK_num(ip->meth);
	if (mx > 0) {
	if (mx < (int)OSSL_NELEM(stack))
	storage = stack;
	else
	storage = OPENSSL_malloc(sizeof(storage) mx);
	if (storage != NULL)
	for (i = 0; i < mx; i++)
	storage[i] = sk_EX_CALLBACK_value(ip->meth, i);
	}
	CRYPTO_THREAD_unlock(ex_data_lock);

	for (i = 0; i < mx; i++) {
	if (storage != NULL)
	f = storage[i];
	else {
	CRYPTO_THREAD_write_lock(ex_data_lock);
	f = sk_EX_CALLBACK_value(ip->meth, i);
	CRYPTO_THREAD_unlock(ex_data_lock);
	}
	if (f != NULL && f->free_func != NULL) {
	ptr = CRYPTO_get_ex_data(ad, i);
	f->free_func(obj, ptr, ad, i, f->argl, f->argp);
	}
	}

	if (storage != stack)
	OPENSSL_free(storage);
	err:
	sk_void_free(ad->sk);
	ad->sk = NULL;
	}

	/*
	* For a given CRYPTO_EX_DATA variable, set the value corresponding to a
	* particular index in the class used by this variable
	*/
	int CRYPTO_set_ex_data(CRYPTO_EX_DATA ad, int idx, void val)
	{
	int i;

	if (ad->sk == NULL) {
	if ((ad->sk = sk_void_new_null()) == NULL) {
	CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	}

	for (i = sk_void_num(ad->sk); i <= idx; ++i) {
	if (!sk_void_push(ad->sk, NULL)) {
	CRYPTOerr(CRYPTO_F_CRYPTO_SET_EX_DATA, ERR_R_MALLOC_FAILURE);
	return 0;
	}
	}
	sk_void_set(ad->sk, idx, val);
	return 1;
	}

	/*
	* For a given CRYPTO_EX_DATA_ variable, get the value corresponding to a
	* particular index in the class used by this variable
	*/
	void CRYPTO_get_ex_data(const CRYPTO_EX_DATA ad, int idx)
	{
	if (ad->sk == NULL \|\| idx >= sk_void_num(ad->sk))
	return NULL;
	return sk_void_value(ad->sk, idx);
	}