// Copyright 2020 Google LLC

//

// 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

//

//      http://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 <errno.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "opusfile/config.h"

#include "opusfile/include/opusfile.h"

// Opusfile fuzzing wrapper to help with automated fuzz testing. It's based on

// https://github.com/xiph/opusfile/blob/master/examples/opusfile_example.c

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {

  int ret, tmp;

  OggOpusFile *of = op_open_memory(data, size, &ret);

  if (!of)

    return 0;

  op_link_count(of);

  int link_index = -1;

  op_pcm_total(of, link_index);

  op_raw_total(of, link_index);

  op_pcm_tell(of);

  op_raw_tell(of);

  ogg_int64_t total_sample_count = 0;

  const int pcm_size = 120 * 48 * 2; // 120ms/ch@48kHz is recommended

  opus_int16 pcm[pcm_size];

  for (;;) {

    ret = op_read_stereo(of, pcm, pcm_size);

    if (ret < 0) {

      break;

    }

    if (op_current_link(of) != link_index) {

      link_index = op_current_link(of);

      op_pcm_total(of, link_index);

      op_raw_total(of, link_index);

      op_pcm_tell(of);

      op_raw_tell(of);

      op_bitrate_instant(of);

      tmp = op_head(of, link_index)->version;

      const OpusTags *tags = op_tags(of, link_index);

      for (int i = 0; i < tags->comments; ++i) {

        // Note: The compare also touches memory allocated for user_comments[i].

        // This is a desired side effect and should be kept even if this

        // comparison is removed.

        if (opus_tagncompare("METADATA_BLOCK_PICTURE", 22,

                             tags->user_comments[i]) == 0) {

          OpusPictureTag pic;

          if (opus_picture_tag_parse(&pic, tags->user_comments[i]) >= 0) {

            opus_picture_tag_clear(&pic);

          }

        }

      }

      if (tags->vendor) {

        tmp = tags->vendor[0];

      }

      int binary_suffix_len;

      opus_tags_get_binary_suffix(tags, &binary_suffix_len);

    }

    if (ret == 0) {

      break;

    }

    total_sample_count += ret;

  }

  if (total_sample_count > 0) {

    // Try random-access PCM reads. The number of tests is arbitrary and the

    // offset is designed to be pseudo-random, but deterministic - this is

    // implemented using Lehmer RNG with a minor hack that probably breaks some

    // properties of the RNG (but that is acceptable).

    ogg_int64_t rng_seed = 1307832949LL;

    for (int i = 0; i < 32; ++i) {

      // Derive the next deterministic offset to test and iterate the RNG.

      rng_seed = (rng_seed * 279470273LL);

      const ogg_int64_t offset = rng_seed % total_sample_count;

      rng_seed = rng_seed % 4294967291LL;

      if (op_pcm_seek(of, offset) == 0) {

        tmp = op_read_stereo(of, pcm, pcm_size);

      }

    }

  }

  op_free(of);

  return 0;

}