static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)
{
    BN_ULONG *a = NULL;
    if (words > (INT_MAX / (4 * BN_BITS2))) {
        BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);
        return NULL;
    }
    if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {
        BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
        return NULL;
    }
    if (BN_get_flags(b, BN_FLG_SECURE))
        a = OPENSSL_secure_zalloc(words * sizeof(*a));
    else
        a = OPENSSL_zalloc(words * sizeof(*a));
    if (a == NULL) {
        BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);
        return NULL;
    }
    assert(b->top <= words);
    if (b->top > 0)
        memcpy(a, b->d, sizeof(*a) * b->top);
    return a;
}
['static\nint ec_GF2m_simple_ladder_post(const EC_GROUP *group,\n                               EC_POINT *r, EC_POINT *s,\n                               EC_POINT *p, BN_CTX *ctx)\n{\n    int ret = 0;\n    BIGNUM *t0, *t1, *t2 = NULL;\n    if (BN_is_zero(r->Z))\n        return EC_POINT_set_to_infinity(group, r);\n    if (BN_is_zero(s->Z)) {\n        if (!EC_POINT_copy(r, p)\n            || !EC_POINT_invert(group, r, ctx)) {\n            ECerr(EC_F_EC_GF2M_SIMPLE_LADDER_POST, ERR_R_EC_LIB);\n            return 0;\n        }\n        return 1;\n    }\n    BN_CTX_start(ctx);\n    t0 = BN_CTX_get(ctx);\n    t1 = BN_CTX_get(ctx);\n    t2 = BN_CTX_get(ctx);\n    if (t2 == NULL) {\n        ECerr(EC_F_EC_GF2M_SIMPLE_LADDER_POST, ERR_R_MALLOC_FAILURE);\n        goto err;\n    }\n    if (!group->meth->field_mul(group, t0, r->Z, s->Z, ctx)\n        || !group->meth->field_mul(group, t1, p->X, r->Z, ctx)\n        || !BN_GF2m_add(t1, r->X, t1)\n        || !group->meth->field_mul(group, t2, p->X, s->Z, ctx)\n        || !group->meth->field_mul(group, r->Z, r->X, t2, ctx)\n        || !BN_GF2m_add(t2, t2, s->X)\n        || !group->meth->field_mul(group, t1, t1, t2, ctx)\n        || !group->meth->field_sqr(group, t2, p->X, ctx)\n        || !BN_GF2m_add(t2, p->Y, t2)\n        || !group->meth->field_mul(group, t2, t2, t0, ctx)\n        || !BN_GF2m_add(t1, t2, t1)\n        || !group->meth->field_mul(group, t2, p->X, t0, ctx)\n        || !group->meth->field_inv(group, t2, t2, ctx)\n        || !group->meth->field_mul(group, t1, t1, t2, ctx)\n        || !group->meth->field_mul(group, r->X, r->Z, t2, ctx)\n        || !BN_GF2m_add(t2, p->X, r->X)\n        || !group->meth->field_mul(group, t2, t2, t1, ctx)\n        || !BN_GF2m_add(r->Y, p->Y, t2)\n        || !BN_one(r->Z))\n        goto err;\n    r->Z_is_one = 1;\n    BN_set_negative(r->X, 0);\n    BN_set_negative(r->Y, 0);\n    ret = 1;\n err:\n    BN_CTX_end(ctx);\n    return ret;\n}', 'BIGNUM *BN_CTX_get(BN_CTX *ctx)\n{\n    BIGNUM *ret;\n    CTXDBG_ENTRY("BN_CTX_get", ctx);\n    if (ctx->err_stack || ctx->too_many)\n        return NULL;\n    if ((ret = BN_POOL_get(&ctx->pool, ctx->flags)) == NULL) {\n        ctx->too_many = 1;\n        BNerr(BN_F_BN_CTX_GET, BN_R_TOO_MANY_TEMPORARY_VARIABLES);\n        return NULL;\n    }\n    BN_zero(ret);\n    ctx->used++;\n    CTXDBG_RET(ctx, ret);\n    return ret;\n}', 'int BN_set_word(BIGNUM *a, BN_ULONG w)\n{\n    bn_check_top(a);\n    if (bn_expand(a, (int)sizeof(BN_ULONG) * 8) == NULL)\n        return 0;\n    a->neg = 0;\n    a->d[0] = w;\n    a->top = (w ? 1 : 0);\n    a->flags &= ~BN_FLG_FIXED_TOP;\n    bn_check_top(a);\n    return 1;\n}', 'int BN_GF2m_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)\n{\n    int i;\n    const BIGNUM *at, *bt;\n    bn_check_top(a);\n    bn_check_top(b);\n    if (a->top < b->top) {\n        at = b;\n        bt = a;\n    } else {\n        at = a;\n        bt = b;\n    }\n    if (bn_wexpand(r, at->top) == NULL)\n        return 0;\n    for (i = 0; i < bt->top; i++) {\n        r->d[i] = at->d[i] ^ bt->d[i];\n    }\n    for (; i < at->top; i++) {\n        r->d[i] = at->d[i];\n    }\n    r->top = at->top;\n    bn_correct_top(r);\n    return 1;\n}', 'BIGNUM *bn_wexpand(BIGNUM *a, int words)\n{\n    return (words <= a->dmax) ? a : bn_expand2(a, words);\n}', 'BIGNUM *bn_expand2(BIGNUM *b, int words)\n{\n    if (words > b->dmax) {\n        BN_ULONG *a = bn_expand_internal(b, words);\n        if (!a)\n            return NULL;\n        if (b->d) {\n            OPENSSL_cleanse(b->d, b->dmax * sizeof(b->d[0]));\n            bn_free_d(b);\n        }\n        b->d = a;\n        b->dmax = words;\n    }\n    return b;\n}', 'static BN_ULONG *bn_expand_internal(const BIGNUM *b, int words)\n{\n    BN_ULONG *a = NULL;\n    if (words > (INT_MAX / (4 * BN_BITS2))) {\n        BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_BIGNUM_TOO_LONG);\n        return NULL;\n    }\n    if (BN_get_flags(b, BN_FLG_STATIC_DATA)) {\n        BNerr(BN_F_BN_EXPAND_INTERNAL, BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);\n        return NULL;\n    }\n    if (BN_get_flags(b, BN_FLG_SECURE))\n        a = OPENSSL_secure_zalloc(words * sizeof(*a));\n    else\n        a = OPENSSL_zalloc(words * sizeof(*a));\n    if (a == NULL) {\n        BNerr(BN_F_BN_EXPAND_INTERNAL, ERR_R_MALLOC_FAILURE);\n        return NULL;\n    }\n    assert(b->top <= words);\n    if (b->top > 0)\n        memcpy(a, b->d, sizeof(*a) * b->top);\n    return a;\n}']