1 /* crypto/bn/bn_ctx.c */
2 /* Written by Ulf Moeller for the OpenSSL project. */
3 /* ====================================================================
4 * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
18 * 3. All advertising materials mentioning features or use of this
19 * software must display the following acknowledgment:
20 * "This product includes software developed by the OpenSSL Project
21 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
23 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
24 * endorse or promote products derived from this software without
25 * prior written permission. For written permission, please contact
26 * openssl-core@openssl.org.
28 * 5. Products derived from this software may not be called "OpenSSL"
29 * nor may "OpenSSL" appear in their names without prior written
30 * permission of the OpenSSL Project.
32 * 6. Redistributions of any form whatsoever must retain the following
34 * "This product includes software developed by the OpenSSL Project
35 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
37 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
38 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
40 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
43 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
44 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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47 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
48 * OF THE POSSIBILITY OF SUCH DAMAGE.
49 * ====================================================================
51 * This product includes cryptographic software written by Eric Young
52 * (eay@cryptsoft.com). This product includes software written by Tim
53 * Hudson (tjh@cryptsoft.com).
57 #if !defined(BN_CTX_DEBUG) && !defined(BN_DEBUG)
69 /* BN_CTX structure details */
71 #define BN_CTX_NUM_POS 12
75 BIGNUM bn[BN_CTX_NUM];
78 int pos[BN_CTX_NUM_POS];
82 #ifndef OPENSSL_NO_DEPRECATED
83 void BN_CTX_init(BN_CTX *ctx)
85 static void BN_CTX_init(BN_CTX *ctx)
88 #if 0 /* explicit version */
94 for (i = 0; i < BN_CTX_NUM; i++)
95 BN_init(&(ctx->bn[i]));
97 memset(ctx, 0, sizeof *ctx);
101 BN_CTX *BN_CTX_new(void)
105 ret=(BN_CTX *)OPENSSL_malloc(sizeof(BN_CTX));
108 BNerr(BN_F_BN_CTX_NEW,ERR_R_MALLOC_FAILURE);
113 ret->flags=BN_FLG_MALLOCED;
117 void BN_CTX_free(BN_CTX *ctx)
121 if (ctx == NULL) return;
122 assert(ctx->depth == 0);
124 for (i=0; i < BN_CTX_NUM; i++)
125 BN_clear_free(&(ctx->bn[i]));
126 if (ctx->flags & BN_FLG_MALLOCED)
130 void BN_CTX_start(BN_CTX *ctx)
132 if (ctx->depth < BN_CTX_NUM_POS)
133 ctx->pos[ctx->depth] = ctx->tos;
138 BIGNUM *BN_CTX_get(BN_CTX *ctx)
140 /* Note: If BN_CTX_get is ever changed to allocate BIGNUMs dynamically,
141 * make sure that if BN_CTX_get fails once it will return NULL again
142 * until BN_CTX_end is called. (This is so that callers have to check
143 * only the last return value.)
145 if (ctx->depth > BN_CTX_NUM_POS || ctx->tos >= BN_CTX_NUM)
149 BNerr(BN_F_BN_CTX_GET,BN_R_TOO_MANY_TEMPORARY_VARIABLES);
150 /* disable error code until BN_CTX_end is called: */
155 return (&(ctx->bn[ctx->tos++]));
158 void BN_CTX_end(BN_CTX *ctx)
160 if (ctx == NULL) return;
161 assert(ctx->depth > 0);
163 /* should never happen, but we can tolerate it if not in
164 * debug mode (could be a 'goto err' in the calling function
165 * before BN_CTX_start was reached) */
170 /* It appears some "scrapbook" uses of BN_CTX result in BIGNUMs being
171 * left in an inconsistent state when they are released (eg. BN_div).
172 * These can trip us up when they get reused, so the safest fix is to
173 * make sure the BIGNUMs are made sane when the context usage is
175 if (ctx->depth < BN_CTX_NUM_POS)
177 ctx->tos = ctx->pos[ctx->depth];
180 while(ctx->tos > ctx->pos[ctx->depth])
181 /* This ensures the BIGNUM is sane(r) for reuse. */
182 ctx->bn[--(ctx->tos)].top = 0;