crypto/engine/eng_list.c - third_party/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);
         return 0;
     }
     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_EC
     dest->ec_meth = src->ec_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 != NULL) {
         /*
          * 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 == NULL)
                 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 (iterator != NULL)
         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, "LIST_ADD", "1", 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 */
 }

 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);
	return 0;
	}
	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_EC
	dest->ec_meth = src->ec_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 != NULL) {
	/*
	* 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 == NULL)
	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 (iterator != NULL)
	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, "LIST_ADD", "1", 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 */
	}

	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;
	}