// Copyright 2017 The BoringSSL Authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include <openssl/bn.h>

#include <openssl/bytestring.h>

#include <openssl/span.h>

#define CHECK(expr)                 \

  do {                              \

    if (!(expr)) {                  \

      printf("%s failed\n", #expr); \

      abort();                      \

    }                               \

  } while (false)

extern "C" int LLVMFuzzerTestOneInput(const uint8_t *buf, size_t len) {

  CBS cbs, child0, child1;

  uint8_t sign0, sign1;

  CBS_init(&cbs, buf, len);

  if (!CBS_get_u16_length_prefixed(&cbs, &child0) ||

      !CBS_get_u8(&child0, &sign0) ||

      CBS_len(&child0) == 0 ||

      !CBS_get_u16_length_prefixed(&cbs, &child1) ||

      !CBS_get_u8(&child1, &sign1) ||

      CBS_len(&child1) == 0) {

    return 0;

  }

  bssl::UniquePtr<BIGNUM> numerator(

      BN_bin2bn(CBS_data(&child0), CBS_len(&child0), nullptr));

  BN_set_negative(numerator.get(), sign0 % 2);

  bssl::UniquePtr<BIGNUM> divisor(

      BN_bin2bn(CBS_data(&child1), CBS_len(&child1), nullptr));

  BN_set_negative(divisor.get(), sign1 % 2);

  if (BN_is_zero(divisor.get())) {

    return 0;

  }

  bssl::UniquePtr<BN_CTX> ctx(BN_CTX_new());

  bssl::UniquePtr<BIGNUM> result(BN_new());

  bssl::UniquePtr<BIGNUM> remainder(BN_new());

  CHECK(ctx);

  CHECK(result);

  CHECK(remainder);

  CHECK(BN_div(result.get(), remainder.get(), numerator.get(), divisor.get(),

               ctx.get()));

  CHECK(BN_ucmp(remainder.get(), divisor.get()) < 0);

  // Check that result*divisor+remainder = numerator.

  CHECK(BN_mul(result.get(), result.get(), divisor.get(), ctx.get()));

  CHECK(BN_add(result.get(), result.get(), remainder.get()));

  CHECK(BN_cmp(result.get(), numerator.get()) == 0);

  return 0;

}