openssl/crypto/engine/eng_list.c - chromium/deps/openssl - Git at Google

 /* crypto/engine/eng_list.c */
 /* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
  * project 2000.
  */
 /* ====================================================================
  * Copyright (c) 1999-2001 The OpenSSL Project.  All rights reserved.
  *
  * 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. All advertising materials mentioning features or use of this
  *    software must display the following acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    licensing@OpenSSL.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED 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 OpenSSL PROJECT OR
  * ITS 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.
  * ====================================================================
  *
  * This product includes cryptographic software written by Eric Young
  * (eay@cryptsoft.com).  This product includes software written by Tim
  * Hudson (tjh@cryptsoft.com).
  *
  */
 /* ====================================================================
  * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
  * ECDH support in OpenSSL originally developed by
  * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
  */

 #include "eng_int.h"

 /* The linked-list of pointers to engine types. engine_list_head
  * incorporates an implicit structural reference but engine_list_tail
  * does not - the latter is a computational niceity and only points
  * to something that is already pointed to by its predecessor in the
  * list (or engine_list_head itself). In the same way, the use of the
  * "prev" pointer in each ENGINE is to save excessive list iteration,
  * it doesn't correspond to an extra structural reference. Hence,
  * engine_list_head, and each non-null "next" pointer account for
  * the list itself assuming exactly 1 structural reference on each
  * list member. */
 static ENGINE *engine_list_head = NULL;
 static ENGINE *engine_list_tail = NULL;

 /* This cleanup function is only needed internally. If it should be called, we
  * register it with the "ENGINE_cleanup()" stack to be called during cleanup. */

 static void engine_list_cleanup(void)
 	{
 	ENGINE *iterator = engine_list_head;

 	while(iterator != NULL)
 		{
 		ENGINE_remove(iterator);
 		iterator = engine_list_head;
 		}
 	return;
 	}

 /* These static functions starting with a lower case "engine_" always
  * take place when CRYPTO_LOCK_ENGINE has been locked up. */
 static int engine_list_add(ENGINE *e)
 	{
 	int conflict = 0;
 	ENGINE *iterator = NULL;

 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	iterator = engine_list_head;
 	while(iterator && !conflict)
 		{
 		conflict = (strcmp(iterator->id, e->id) == 0);
 		iterator = iterator->next;
 		}
 	if(conflict)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
 			ENGINE_R_CONFLICTING_ENGINE_ID);
 		return 0;
 		}
 	if(engine_list_head == NULL)
 		{
 		/* We are adding to an empty list. */
 		if(engine_list_tail)
 			{
 			ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
 				ENGINE_R_INTERNAL_LIST_ERROR);
 			return 0;
 			}
 		engine_list_head = e;
 		e->prev = NULL;
 		/* The first time the list allocates, we should register the
 		 * cleanup. */
 		engine_cleanup_add_last(engine_list_cleanup);
 		}
 	else
 		{
 		/* We are adding to the tail of an existing list. */
 		if((engine_list_tail == NULL) ||
 				(engine_list_tail->next != NULL))
 			{
 			ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
 				ENGINE_R_INTERNAL_LIST_ERROR);
 			return 0;
 			}
 		engine_list_tail->next = e;
 		e->prev = engine_list_tail;
 		}
 	/* Having the engine in the list assumes a structural
 	 * reference. */
 	e->struct_ref++;
 	engine_ref_debug(e, 0, 1)
 	/* However it came to be, e is the last item in the list. */
 	engine_list_tail = e;
 	e->next = NULL;
 	return 1;
 	}

 static int engine_list_remove(ENGINE *e)
 	{
 	ENGINE *iterator;

 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	/* We need to check that e is in our linked list! */
 	iterator = engine_list_head;
 	while(iterator && (iterator != e))
 		iterator = iterator->next;
 	if(iterator == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE,
 			ENGINE_R_ENGINE_IS_NOT_IN_LIST);
 		return 0;
 		}
 	/* un-link e from the chain. */
 	if(e->next)
 		e->next->prev = e->prev;
 	if(e->prev)
 		e->prev->next = e->next;
 	/* Correct our head/tail if necessary. */
 	if(engine_list_head == e)
 		engine_list_head = e->next;
 	if(engine_list_tail == e)
 		engine_list_tail = e->prev;
 	engine_free_util(e, 0);
 	return 1;
 	}

 /* Get the first/last "ENGINE" type available. */
 ENGINE *ENGINE_get_first(void)
 	{
 	ENGINE *ret;

 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	ret = engine_list_head;
 	if(ret)
 		{
 		ret->struct_ref++;
 		engine_ref_debug(ret, 0, 1)
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	return ret;
 	}

 ENGINE *ENGINE_get_last(void)
 	{
 	ENGINE *ret;

 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	ret = engine_list_tail;
 	if(ret)
 		{
 		ret->struct_ref++;
 		engine_ref_debug(ret, 0, 1)
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	return ret;
 	}

 /* Iterate to the next/previous "ENGINE" type (NULL = end of the list). */
 ENGINE *ENGINE_get_next(ENGINE *e)
 	{
 	ENGINE *ret = NULL;
 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_GET_NEXT,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	ret = e->next;
 	if(ret)
 		{
 		/* Return a valid structural refernce to the next ENGINE */
 		ret->struct_ref++;
 		engine_ref_debug(ret, 0, 1)
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	/* Release the structural reference to the previous ENGINE */
 	ENGINE_free(e);
 	return ret;
 	}

 ENGINE *ENGINE_get_prev(ENGINE *e)
 	{
 	ENGINE *ret = NULL;
 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_GET_PREV,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	ret = e->prev;
 	if(ret)
 		{
 		/* Return a valid structural reference to the next ENGINE */
 		ret->struct_ref++;
 		engine_ref_debug(ret, 0, 1)
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	/* Release the structural reference to the previous ENGINE */
 	ENGINE_free(e);
 	return ret;
 	}

 /* Add another "ENGINE" type into the list. */
 int ENGINE_add(ENGINE *e)
 	{
 	int to_return = 1;
 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_ADD,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	if((e->id == NULL) || (e->name == NULL))
 		{
 		ENGINEerr(ENGINE_F_ENGINE_ADD,
 			ENGINE_R_ID_OR_NAME_MISSING);
 		}
 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	if(!engine_list_add(e))
 		{
 		ENGINEerr(ENGINE_F_ENGINE_ADD,
 			ENGINE_R_INTERNAL_LIST_ERROR);
 		to_return = 0;
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	return to_return;
 	}

 /* Remove an existing "ENGINE" type from the array. */
 int ENGINE_remove(ENGINE *e)
 	{
 	int to_return = 1;
 	if(e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_REMOVE,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	if(!engine_list_remove(e))
 		{
 		ENGINEerr(ENGINE_F_ENGINE_REMOVE,
 			ENGINE_R_INTERNAL_LIST_ERROR);
 		to_return = 0;
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 	return to_return;
 	}

 static void engine_cpy(ENGINE *dest, const ENGINE *src)
 	{
 	dest->id = src->id;
 	dest->name = src->name;
 #ifndef OPENSSL_NO_RSA
 	dest->rsa_meth = src->rsa_meth;
 #endif
 #ifndef OPENSSL_NO_DSA
 	dest->dsa_meth = src->dsa_meth;
 #endif
 #ifndef OPENSSL_NO_DH
 	dest->dh_meth = src->dh_meth;
 #endif
 #ifndef OPENSSL_NO_ECDH
 	dest->ecdh_meth = src->ecdh_meth;
 #endif
 #ifndef OPENSSL_NO_ECDSA
 	dest->ecdsa_meth = src->ecdsa_meth;
 #endif
 	dest->rand_meth = src->rand_meth;
 	dest->store_meth = src->store_meth;
 	dest->ciphers = src->ciphers;
 	dest->digests = src->digests;
 	dest->pkey_meths = src->pkey_meths;
 	dest->destroy = src->destroy;
 	dest->init = src->init;
 	dest->finish = src->finish;
 	dest->ctrl = src->ctrl;
 	dest->load_privkey = src->load_privkey;
 	dest->load_pubkey = src->load_pubkey;
 	dest->cmd_defns = src->cmd_defns;
 	dest->flags = src->flags;
 	}

 ENGINE *ENGINE_by_id(const char *id)
 	{
 	ENGINE *iterator;
 	char *load_dir = NULL;
 	if(id == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_BY_ID,
 			ERR_R_PASSED_NULL_PARAMETER);
 		return NULL;
 		}
 	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
 	iterator = engine_list_head;
 	while(iterator && (strcmp(id, iterator->id) != 0))
 		iterator = iterator->next;
 	if(iterator)
 		{
 		/* We need to return a structural reference. If this is an
 		 * ENGINE type that returns copies, make a duplicate - otherwise
 		 * increment the existing ENGINE's reference count. */
 		if(iterator->flags & ENGINE_FLAGS_BY_ID_COPY)
 			{
 			ENGINE *cp = ENGINE_new();
 			if(!cp)
 				iterator = NULL;
 			else
 				{
 				engine_cpy(cp, iterator);
 				iterator = cp;
 				}
 			}
 		else
 			{
 			iterator->struct_ref++;
 			engine_ref_debug(iterator, 0, 1)
 			}
 		}
 	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
 #if 0
 	if(iterator == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_BY_ID,
 			ENGINE_R_NO_SUCH_ENGINE);
 		ERR_add_error_data(2, "id=", id);
 		}
 	return iterator;
 #else
 	/* EEK! Experimental code starts */
 	if(iterator) return iterator;
 	/* Prevent infinite recusrion if we're looking for the dynamic engine. */
 	if (strcmp(id, "dynamic"))
 		{
 #ifdef OPENSSL_SYS_VMS
 		if((load_dir = getenv("OPENSSL_ENGINES")) == 0) load_dir = "SSLROOT:[ENGINES]";
 #else
 		if((load_dir = getenv("OPENSSL_ENGINES")) == 0) load_dir = ENGINESDIR;
 #endif
 		iterator = ENGINE_by_id("dynamic");
 		if(!iterator || !ENGINE_ctrl_cmd_string(iterator, "ID", id, 0) ||
 				!ENGINE_ctrl_cmd_string(iterator, "DIR_LOAD", "2", 0) ||
 				!ENGINE_ctrl_cmd_string(iterator, "DIR_ADD",
 					load_dir, 0) ||
 				!ENGINE_ctrl_cmd_string(iterator, "LOAD", NULL, 0))
 				goto notfound;
 		return iterator;
 		}
 notfound:
 	ENGINE_free(iterator);
 	ENGINEerr(ENGINE_F_ENGINE_BY_ID,ENGINE_R_NO_SUCH_ENGINE);
 	ERR_add_error_data(2, "id=", id);
 	return NULL;
 	/* EEK! Experimental code ends */
 #endif
 	}

 int ENGINE_up_ref(ENGINE *e)
 	{
 	if (e == NULL)
 		{
 		ENGINEerr(ENGINE_F_ENGINE_UP_REF,ERR_R_PASSED_NULL_PARAMETER);
 		return 0;
 		}
 	CRYPTO_add(&e->struct_ref,1,CRYPTO_LOCK_ENGINE);
 	return 1;
 	}
	/* crypto/engine/eng_list.c */
	/* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
	* project 2000.
	*/
	/* ====================================================================
	* Copyright (c) 1999-2001 The OpenSSL Project. All rights reserved.
	*
	* 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. All advertising materials mentioning features or use of this
	* software must display the following acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* licensing@OpenSSL.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED 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 OpenSSL PROJECT OR
	* ITS 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.
	* ====================================================================
	*
	* This product includes cryptographic software written by Eric Young
	* (eay@cryptsoft.com). This product includes software written by Tim
	* Hudson (tjh@cryptsoft.com).
	*
	*/
	/* ====================================================================
	* Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
	* ECDH support in OpenSSL originally developed by
	* SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
	*/

	#include "eng_int.h"

	/* The linked-list of pointers to engine types. engine_list_head
	* incorporates an implicit structural reference but engine_list_tail
	* does not - the latter is a computational niceity and only points
	* to something that is already pointed to by its predecessor in the
	* list (or engine_list_head itself). In the same way, the use of the
	* "prev" pointer in each ENGINE is to save excessive list iteration,
	* it doesn't correspond to an extra structural reference. Hence,
	* engine_list_head, and each non-null "next" pointer account for
	* the list itself assuming exactly 1 structural reference on each
	* list member. */
	static ENGINE *engine_list_head = NULL;
	static ENGINE *engine_list_tail = NULL;

	/* This cleanup function is only needed internally. If it should be called, we
	* register it with the "ENGINE_cleanup()" stack to be called during cleanup. */

	static void engine_list_cleanup(void)
	{
	ENGINE *iterator = engine_list_head;

	while(iterator != NULL)
	{
	ENGINE_remove(iterator);
	iterator = engine_list_head;
	}
	return;
	}

	/* These static functions starting with a lower case "engine_" always
	* take place when CRYPTO_LOCK_ENGINE has been locked up. */
	static int engine_list_add(ENGINE *e)
	{
	int conflict = 0;
	ENGINE *iterator = NULL;

	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	iterator = engine_list_head;
	while(iterator && !conflict)
	{
	conflict = (strcmp(iterator->id, e->id) == 0);
	iterator = iterator->next;
	}
	if(conflict)
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
	ENGINE_R_CONFLICTING_ENGINE_ID);
	return 0;
	}
	if(engine_list_head == NULL)
	{
	/* We are adding to an empty list. */
	if(engine_list_tail)
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
	ENGINE_R_INTERNAL_LIST_ERROR);
	return 0;
	}
	engine_list_head = e;
	e->prev = NULL;
	/* The first time the list allocates, we should register the
	* cleanup. */
	engine_cleanup_add_last(engine_list_cleanup);
	}
	else
	{
	/* We are adding to the tail of an existing list. */
	if((engine_list_tail == NULL) \|\|
	(engine_list_tail->next != NULL))
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_ADD,
	ENGINE_R_INTERNAL_LIST_ERROR);
	return 0;
	}
	engine_list_tail->next = e;
	e->prev = engine_list_tail;
	}
	/* Having the engine in the list assumes a structural
	* reference. */
	e->struct_ref++;
	engine_ref_debug(e, 0, 1)
	/* However it came to be, e is the last item in the list. */
	engine_list_tail = e;
	e->next = NULL;
	return 1;
	}

	static int engine_list_remove(ENGINE *e)
	{
	ENGINE *iterator;

	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	/* We need to check that e is in our linked list! */
	iterator = engine_list_head;
	while(iterator && (iterator != e))
	iterator = iterator->next;
	if(iterator == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE,
	ENGINE_R_ENGINE_IS_NOT_IN_LIST);
	return 0;
	}
	/* un-link e from the chain. */
	if(e->next)
	e->next->prev = e->prev;
	if(e->prev)
	e->prev->next = e->next;
	/* Correct our head/tail if necessary. */
	if(engine_list_head == e)
	engine_list_head = e->next;
	if(engine_list_tail == e)
	engine_list_tail = e->prev;
	engine_free_util(e, 0);
	return 1;
	}

	/* Get the first/last "ENGINE" type available. */
	ENGINE *ENGINE_get_first(void)
	{
	ENGINE *ret;

	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	ret = engine_list_head;
	if(ret)
	{
	ret->struct_ref++;
	engine_ref_debug(ret, 0, 1)
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	return ret;
	}

	ENGINE *ENGINE_get_last(void)
	{
	ENGINE *ret;

	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	ret = engine_list_tail;
	if(ret)
	{
	ret->struct_ref++;
	engine_ref_debug(ret, 0, 1)
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	return ret;
	}

	/* Iterate to the next/previous "ENGINE" type (NULL = end of the list). */
	ENGINE ENGINE_get_next(ENGINE e)
	{
	ENGINE *ret = NULL;
	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_GET_NEXT,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	ret = e->next;
	if(ret)
	{
	/* Return a valid structural refernce to the next ENGINE */
	ret->struct_ref++;
	engine_ref_debug(ret, 0, 1)
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	/* Release the structural reference to the previous ENGINE */
	ENGINE_free(e);
	return ret;
	}

	ENGINE ENGINE_get_prev(ENGINE e)
	{
	ENGINE *ret = NULL;
	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_GET_PREV,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	ret = e->prev;
	if(ret)
	{
	/* Return a valid structural reference to the next ENGINE */
	ret->struct_ref++;
	engine_ref_debug(ret, 0, 1)
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	/* Release the structural reference to the previous ENGINE */
	ENGINE_free(e);
	return ret;
	}

	/* Add another "ENGINE" type into the list. */
	int ENGINE_add(ENGINE *e)
	{
	int to_return = 1;
	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_ADD,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	if((e->id == NULL) \|\| (e->name == NULL))
	{
	ENGINEerr(ENGINE_F_ENGINE_ADD,
	ENGINE_R_ID_OR_NAME_MISSING);
	}
	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	if(!engine_list_add(e))
	{
	ENGINEerr(ENGINE_F_ENGINE_ADD,
	ENGINE_R_INTERNAL_LIST_ERROR);
	to_return = 0;
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	return to_return;
	}

	/* Remove an existing "ENGINE" type from the array. */
	int ENGINE_remove(ENGINE *e)
	{
	int to_return = 1;
	if(e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_REMOVE,
	ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	if(!engine_list_remove(e))
	{
	ENGINEerr(ENGINE_F_ENGINE_REMOVE,
	ENGINE_R_INTERNAL_LIST_ERROR);
	to_return = 0;
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	return to_return;
	}

	static void engine_cpy(ENGINE dest, const ENGINE src)
	{
	dest->id = src->id;
	dest->name = src->name;
	#ifndef OPENSSL_NO_RSA
	dest->rsa_meth = src->rsa_meth;
	#endif
	#ifndef OPENSSL_NO_DSA
	dest->dsa_meth = src->dsa_meth;
	#endif
	#ifndef OPENSSL_NO_DH
	dest->dh_meth = src->dh_meth;
	#endif
	#ifndef OPENSSL_NO_ECDH
	dest->ecdh_meth = src->ecdh_meth;
	#endif
	#ifndef OPENSSL_NO_ECDSA
	dest->ecdsa_meth = src->ecdsa_meth;
	#endif
	dest->rand_meth = src->rand_meth;
	dest->store_meth = src->store_meth;
	dest->ciphers = src->ciphers;
	dest->digests = src->digests;
	dest->pkey_meths = src->pkey_meths;
	dest->destroy = src->destroy;
	dest->init = src->init;
	dest->finish = src->finish;
	dest->ctrl = src->ctrl;
	dest->load_privkey = src->load_privkey;
	dest->load_pubkey = src->load_pubkey;
	dest->cmd_defns = src->cmd_defns;
	dest->flags = src->flags;
	}

	ENGINE ENGINE_by_id(const char id)
	{
	ENGINE *iterator;
	char *load_dir = NULL;
	if(id == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_BY_ID,
	ERR_R_PASSED_NULL_PARAMETER);
	return NULL;
	}
	CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
	iterator = engine_list_head;
	while(iterator && (strcmp(id, iterator->id) != 0))
	iterator = iterator->next;
	if(iterator)
	{
	/* We need to return a structural reference. If this is an
	* ENGINE type that returns copies, make a duplicate - otherwise
	* increment the existing ENGINE's reference count. */
	if(iterator->flags & ENGINE_FLAGS_BY_ID_COPY)
	{
	ENGINE *cp = ENGINE_new();
	if(!cp)
	iterator = NULL;
	else
	{
	engine_cpy(cp, iterator);
	iterator = cp;
	}
	}
	else
	{
	iterator->struct_ref++;
	engine_ref_debug(iterator, 0, 1)
	}
	}
	CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
	#if 0
	if(iterator == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_BY_ID,
	ENGINE_R_NO_SUCH_ENGINE);
	ERR_add_error_data(2, "id=", id);
	}
	return iterator;
	#else
	/* EEK! Experimental code starts */
	if(iterator) return iterator;
	/* Prevent infinite recusrion if we're looking for the dynamic engine. */
	if (strcmp(id, "dynamic"))
	{
	#ifdef OPENSSL_SYS_VMS
	if((load_dir = getenv("OPENSSL_ENGINES")) == 0) load_dir = "SSLROOT:[ENGINES]";
	#else
	if((load_dir = getenv("OPENSSL_ENGINES")) == 0) load_dir = ENGINESDIR;
	#endif
	iterator = ENGINE_by_id("dynamic");
	if(!iterator \|\| !ENGINE_ctrl_cmd_string(iterator, "ID", id, 0) \|\|
	!ENGINE_ctrl_cmd_string(iterator, "DIR_LOAD", "2", 0) \|\|
	!ENGINE_ctrl_cmd_string(iterator, "DIR_ADD",
	load_dir, 0) \|\|
	!ENGINE_ctrl_cmd_string(iterator, "LOAD", NULL, 0))
	goto notfound;
	return iterator;
	}
	notfound:
	ENGINE_free(iterator);
	ENGINEerr(ENGINE_F_ENGINE_BY_ID,ENGINE_R_NO_SUCH_ENGINE);
	ERR_add_error_data(2, "id=", id);
	return NULL;
	/* EEK! Experimental code ends */
	#endif
	}

	int ENGINE_up_ref(ENGINE *e)
	{
	if (e == NULL)
	{
	ENGINEerr(ENGINE_F_ENGINE_UP_REF,ERR_R_PASSED_NULL_PARAMETER);
	return 0;
	}
	CRYPTO_add(&e->struct_ref,1,CRYPTO_LOCK_ENGINE);
	return 1;
	}