frost/secp256k1-zkp
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Eliminate all side-effects from VERIFY_CHECK() usage.

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The side-effects make review somewhat harder because 99.9% of the
 time the macro usage has no sideeffects, so they're easily ignored.

The main motivation for avoiding the side effects is so that the
 macro can be completely stubbed out for branch coverage analysis
 otherwise all the unreachable verify code gets counted against
 coverage.
This commit is contained in:
Gregory Maxwell
2015-10-19 23:55:10 +00:00
parent b30fc85c9e
commit e3cd679634
4 changed files with 17 additions and 4 deletions
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2
src/num_gmp_impl.h
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@@ -70,6 +70,7 @@ static void secp256k1_num_add_abs(secp256k1_num *r, const secp256k1_num *a, cons
static void secp256k1_num_sub_abs(secp256k1_num *r, const secp256k1_num *a, const secp256k1_num *b) {
mp_limb_t c = mpn_sub(r->data, a->data, a->limbs, b->data, b->limbs);
(void)c;
VERIFY_CHECK(c == 0);
r->limbs = a->limbs;
while (r->limbs > 1 && r->data[r->limbs-1]==0) {
@@ -125,6 +126,7 @@ static void secp256k1_num_mod_inverse(secp256k1_num *r, const secp256k1_num *a,
}
sn = NUM_LIMBS+1;
gn = mpn_gcdext(g, r->data, &sn, u, m->limbs, v, m->limbs);
(void)gn;
VERIFY_CHECK(gn == 1);
VERIFY_CHECK(g[0] == 1);
r->neg = a->neg ^ m->neg;