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/* crypto/bn/bn_ctx.c */
/* Written by Ulf Moeller for the OpenSSL project. */
/* ====================================================================
* Copyright (c) 1998-2000 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
* openssl-core@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).
*
*/
#if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
#ifndef NDEBUG
#define NDEBUG
#endif
#endif
#include <stdio.h>
#include <assert.h>
#include "cryptlib.h"
#include "bn_lcl.h"
/* BN_CTX structure details */
#define BN_CTX_NUM 32
#define BN_CTX_NUM_POS 12
struct bignum_ctx
{
int tos;
BIGNUM bn[BN_CTX_NUM];
int flags;
int depth;
int pos[BN_CTX_NUM_POS];
int too_many;
};
#ifndef OPENSSL_NO_DEPRECATED
void BN_CTX_init(BN_CTX *ctx)
#else
static void BN_CTX_init(BN_CTX *ctx)
#endif
{
#if 0 /* explicit version */
int i;
ctx->tos = 0;
ctx->flags = 0;
ctx->depth = 0;
ctx->too_many = 0;
for (i = 0; i < BN_CTX_NUM; i++)
BN_init(&(ctx->bn[i]));
#else
memset(ctx, 0, sizeof *ctx);
#endif
}
BN_CTX *BN_CTX_new(void)
{
BN_CTX *ret;
ret=(BN_CTX *)OPENSSL_malloc(sizeof(BN_CTX));
if (ret == NULL)
{
BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
return(NULL);
}
BN_CTX_init(ret);
ret->flags=BN_FLG_MALLOCED;
return(ret);
}
void BN_CTX_free(BN_CTX *ctx)
{
int i;
if (ctx == NULL) return;
assert(ctx->depth == 0);
for (i=0; i < BN_CTX_NUM; i++) {
bn_check_top(&(ctx->bn[i]));
if (ctx->bn[i].d)
BN_clear_free(&(ctx->bn[i]));
}
if (ctx->flags & BN_FLG_MALLOCED)
OPENSSL_free(ctx);
}
void BN_CTX_start(BN_CTX *ctx)
{
if (ctx->depth < BN_CTX_NUM_POS)
ctx->pos[ctx->depth] = ctx->tos;
ctx->depth++;
}
BIGNUM *BN_CTX_get(BN_CTX *ctx)
{
/* Note: If BN_CTX_get is ever changed to allocate BIGNUMs dynamically,
* make sure that if BN_CTX_get fails once it will return NULL again
* until BN_CTX_end is called. (This is so that callers have to check
* only the last return value.)
*/
if (ctx->depth > BN_CTX_NUM_POS || ctx->tos >= BN_CTX_NUM)
{
if (!ctx->too_many)
{
BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
/* disable error code until BN_CTX_end is called: */
ctx->too_many = 1;
}
return NULL;
}
/* always return a 'zeroed' bignum */
ctx->bn[ctx->tos].top = 0;
return (&(ctx->bn[ctx->tos++]));
}
void BN_CTX_end(BN_CTX *ctx)
{
if (ctx == NULL) return;
assert(ctx->depth > 0);
if (ctx->depth == 0)
/* should never happen, but we can tolerate it if not in
* debug mode (could be a 'goto err' in the calling function
* before BN_CTX_start was reached) */
BN_CTX_start(ctx);
ctx->too_many = 0;
ctx->depth--;
if (ctx->depth < BN_CTX_NUM_POS)
#ifndef BN_DEBUG
ctx->tos = ctx->pos[ctx->depth];
#else
while(ctx->tos > ctx->pos[ctx->depth])
bn_check_top(&ctx->bn[--(ctx->tos)]);
#endif
}
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