From 5d735465d1b5b7853506979946ad5730cc3615bb Mon Sep 17 00:00:00 2001
From: Geoff Thorpe
Date: Sat, 13 Mar 2004 23:04:15 +0000
Subject: [PATCH] The efforts to eliminate the dual-representation of zero and
to ensure bignums are passed in and out of functions and APIs in a consistent
form has highlighted that zero-valued bignums don't need any allocated word
data. The use of BN_set_word() to initialise a bignum to zero causes needless
allocation and gives it a return value that must be checked. This change
converts BN_zero() to a self-contained macro that has no return/expression
value and does not cause any expansion of bignum data.
Note, it would be tempting to rewrite the deprecated version as a
success-valued comma expression, such as;
#define BN_zero(a) ((a)->top = (a)->neg = 0, 1)
However, this evaluates 'a' twice and would confuse initialisation loops
(eg. while(..) { BN_zero(bn++) } ). As such, the deprecated version
continues to use BN_set_word().
---
crypto/bn/bn.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/crypto/bn/bn.h b/crypto/bn/bn.h
index f58d5f55a0..a01f193daa 100644
--- a/crypto/bn/bn.h
+++ b/crypto/bn/bn.h
@@ -372,7 +372,17 @@ int BN_GENCB_call(BN_GENCB *cb, int a, int b);
#define BN_is_odd(a) (((a)->top > 0) && ((a)->d[0] & 1))
#define BN_one(a) (BN_set_word((a),1))
+#define BN_zero_ex(a) \
+ do { \
+ BIGNUM *_tmp_bn = (a); \
+ _tmp_bn->top = 0; \
+ _tmp_bn->neg = 0; \
+ } while(0)
+#ifdef OPENSSL_NO_DEPRECATED
+#define BN_zero(a) BN_zero_ex(a)
+#else
#define BN_zero(a) (BN_set_word((a),0))
+#endif
/* BN_set_sign(BIGNUM *, int) sets the sign of a BIGNUM
* (0 for a non-negative value, 1 for negative) */
#define BN_set_sign(a,b) ((a)->neg = (b))
--
2.34.1