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 int test_mod(void)\n{\n    BIGNUM *a = NULL, *b = NULL, *c = NULL, *d = NULL, *e = NULL;\n    int st = 0, i;\n    if (!TEST_ptr(a = BN_new())\n            || !TEST_ptr(b = BN_new())\n            || !TEST_ptr(c = BN_new())\n            || !TEST_ptr(d = BN_new())\n            || !TEST_ptr(e = BN_new()))\n        goto err;\n    if (!(TEST_true(BN_bntest_rand(a, 1024, 0, 0))))\n        goto err;\n    for (i = 0; i < NUM0; i++) {\n        if (!(TEST_true(BN_bntest_rand(b, 450 + i * 10, 0, 0))))\n            goto err;\n        BN_set_negative(a, rand_neg());\n        BN_set_negative(b, rand_neg());\n        if (!(TEST_true(BN_mod(c, a, b, ctx))\n                && TEST_true(BN_div(d, e, a, b, ctx))\n                && TEST_true(BN_sub(e, e, c))\n                && TEST_BN_eq_zero(e)))\n            goto err;\n    }\n    st = 1;\n err:\n    BN_free(a);\n    BN_free(b);\n    BN_free(c);\n    BN_free(d);\n    BN_free(e);\n    return st;\n}', 'int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)\n{\n    return bnrand(TESTING, rnd, bits, top, bottom, NULL);\n}', 'static int bnrand(BNRAND_FLAG flag, BIGNUM *rnd, int bits, int top, int bottom,\n                  BN_CTX *ctx)\n{\n    unsigned char *buf = NULL;\n    int b, ret = 0, bit, bytes, mask;\n    OPENSSL_CTX *libctx = bn_get_lib_ctx(ctx);\n    if (bits == 0) {\n        if (top != BN_RAND_TOP_ANY || bottom != BN_RAND_BOTTOM_ANY)\n            goto toosmall;\n        BN_zero(rnd);\n        return 1;\n    }\n    if (bits < 0 || (bits == 1 && top > 0))\n        goto toosmall;\n    bytes = (bits + 7) / 8;\n    bit = (bits - 1) % 8;\n    mask = 0xff << (bit + 1);\n    buf = OPENSSL_malloc(bytes);\n    if (buf == NULL) {\n        BNerr(BN_F_BNRAND, ERR_R_MALLOC_FAILURE);\n        goto err;\n    }\n    b = flag == NORMAL ? rand_bytes_ex(libctx, buf, bytes)\n                       : rand_priv_bytes_ex(libctx, buf, bytes);\n    if (b <= 0)\n        goto err;\n    if (flag == TESTING) {\n        int i;\n        unsigned char c;\n        for (i = 0; i < bytes; i++) {\n            if (rand_bytes_ex(libctx, &c, 1) <= 0)\n                goto err;\n            if (c >= 128 && i > 0)\n                buf[i] = buf[i - 1];\n            else if (c < 42)\n                buf[i] = 0;\n            else if (c < 84)\n                buf[i] = 255;\n        }\n    }\n    if (top >= 0) {\n        if (top) {\n            if (bit == 0) {\n                buf[0] = 1;\n                buf[1] |= 0x80;\n            } else {\n                buf[0] |= (3 << (bit - 1));\n            }\n        } else {\n            buf[0] |= (1 << bit);\n        }\n    }\n    buf[0] &= ~mask;\n    if (bottom)\n        buf[bytes - 1] |= 1;\n    if (!BN_bin2bn(buf, bytes, rnd))\n        goto err;\n    ret = 1;\n err:\n    OPENSSL_clear_free(buf, bytes);\n    bn_check_top(rnd);\n    return ret;\ntoosmall:\n    BNerr(BN_F_BNRAND, BN_R_BITS_TOO_SMALL);\n    return 0;\n}', 'int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,\n           BN_CTX *ctx)\n{\n    int ret;\n    if (BN_is_zero(divisor)) {\n        BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO);\n        return 0;\n    }\n    if (divisor->d[divisor->top - 1] == 0) {\n        BNerr(BN_F_BN_DIV, BN_R_NOT_INITIALIZED);\n        return 0;\n    }\n    ret = bn_div_fixed_top(dv, rm, num, divisor, ctx);\n    if (ret) {\n        if (dv != NULL)\n            bn_correct_top(dv);\n        if (rm != NULL)\n            bn_correct_top(rm);\n    }\n    return ret;\n}', 'int bn_div_fixed_top(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,\n                     const BIGNUM *divisor, BN_CTX *ctx)\n{\n    int norm_shift, i, j, loop;\n    BIGNUM *tmp, *snum, *sdiv, *res;\n    BN_ULONG *resp, *wnum, *wnumtop;\n    BN_ULONG d0, d1;\n    int num_n, div_n;\n    assert(divisor->top > 0 && divisor->d[divisor->top - 1] != 0);\n    bn_check_top(num);\n    bn_check_top(divisor);\n    bn_check_top(dv);\n    bn_check_top(rm);\n    BN_CTX_start(ctx);\n    res = (dv == NULL) ? BN_CTX_get(ctx) : dv;\n    tmp = BN_CTX_get(ctx);\n    snum = BN_CTX_get(ctx);\n    sdiv = BN_CTX_get(ctx);\n    if (sdiv == NULL)\n        goto err;\n    if (!BN_copy(sdiv, divisor))\n        goto err;\n    norm_shift = bn_left_align(sdiv);\n    sdiv->neg = 0;\n    if (!(bn_lshift_fixed_top(snum, num, norm_shift)))\n        goto err;\n    div_n = sdiv->top;\n    num_n = snum->top;\n    if (num_n <= div_n) {\n        if (bn_wexpand(snum, div_n + 1) == NULL)\n            goto err;\n        memset(&(snum->d[num_n]), 0, (div_n - num_n + 1) * sizeof(BN_ULONG));\n        snum->top = num_n = div_n + 1;\n    }\n    loop = num_n - div_n;\n    wnum = &(snum->d[loop]);\n    wnumtop = &(snum->d[num_n - 1]);\n    d0 = sdiv->d[div_n - 1];\n    d1 = (div_n == 1) ? 0 : sdiv->d[div_n - 2];\n    if (!bn_wexpand(res, loop))\n        goto err;\n    res->neg = (num->neg ^ divisor->neg);\n    res->top = loop;\n    res->flags |= BN_FLG_FIXED_TOP;\n    resp = &(res->d[loop]);\n    if (!bn_wexpand(tmp, (div_n + 1)))\n        goto err;\n    for (i = 0; i < loop; i++, wnumtop--) {\n        BN_ULONG q, l0;\n# if defined(BN_DIV3W)\n        q = bn_div_3_words(wnumtop, d1, d0);\n# else\n        BN_ULONG n0, n1, rem = 0;\n        n0 = wnumtop[0];\n        n1 = wnumtop[-1];\n        if (n0 == d0)\n            q = BN_MASK2;\n        else {\n            BN_ULONG n2 = (wnumtop == wnum) ? 0 : wnumtop[-2];\n#  ifdef BN_LLONG\n            BN_ULLONG t2;\n#   if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)\n            q = (BN_ULONG)(((((BN_ULLONG) n0) << BN_BITS2) | n1) / d0);\n#   else\n            q = bn_div_words(n0, n1, d0);\n#   endif\n#   ifndef REMAINDER_IS_ALREADY_CALCULATED\n            rem = (n1 - q * d0) & BN_MASK2;\n#   endif\n            t2 = (BN_ULLONG) d1 *q;\n            for (;;) {\n                if (t2 <= ((((BN_ULLONG) rem) << BN_BITS2) | n2))\n                    break;\n                q--;\n                rem += d0;\n                if (rem < d0)\n                    break;\n                t2 -= d1;\n            }\n#  else\n            BN_ULONG t2l, t2h;\n            q = bn_div_words(n0, n1, d0);\n#   ifndef REMAINDER_IS_ALREADY_CALCULATED\n            rem = (n1 - q * d0) & BN_MASK2;\n#   endif\n#   if defined(BN_UMULT_LOHI)\n            BN_UMULT_LOHI(t2l, t2h, d1, q);\n#   elif defined(BN_UMULT_HIGH)\n            t2l = d1 * q;\n            t2h = BN_UMULT_HIGH(d1, q);\n#   else\n            {\n                BN_ULONG ql, qh;\n                t2l = LBITS(d1);\n                t2h = HBITS(d1);\n                ql = LBITS(q);\n                qh = HBITS(q);\n                mul64(t2l, t2h, ql, qh);\n            }\n#   endif\n            for (;;) {\n                if ((t2h < rem) || ((t2h == rem) && (t2l <= n2)))\n                    break;\n                q--;\n                rem += d0;\n                if (rem < d0)\n                    break;\n                if (t2l < d1)\n                    t2h--;\n                t2l -= d1;\n            }\n#  endif\n        }\n# endif\n        l0 = bn_mul_words(tmp->d, sdiv->d, div_n, q);\n        tmp->d[div_n] = l0;\n        wnum--;\n        l0 = bn_sub_words(wnum, wnum, tmp->d, div_n + 1);\n        q -= l0;\n        for (l0 = 0 - l0, j = 0; j < div_n; j++)\n            tmp->d[j] = sdiv->d[j] & l0;\n        l0 = bn_add_words(wnum, wnum, tmp->d, div_n);\n        (*wnumtop) += l0;\n        assert((*wnumtop) == 0);\n        *--resp = q;\n    }\n    snum->neg = num->neg;\n    snum->top = div_n;\n    snum->flags |= BN_FLG_FIXED_TOP;\n    if (rm != NULL)\n        bn_rshift_fixed_top(rm, snum, norm_shift);\n    BN_CTX_end(ctx);\n    return 1;\n err:\n    bn_check_top(rm);\n    BN_CTX_end(ctx);\n    return 0;\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}']