// Copyright 2018 Google Inc.

//

// 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 <algorithm>

#include <cstddef>

#include <cstdint>

#include <cstring>

#include <string_view>

#include "./fuzz_utils.h"

#include "src/dec/webpi_dec.h"

#include "src/utils/rescaler_utils.h"

#include "src/webp/decode.h"

namespace {

void AdvancedApiTest(std::string_view blob, uint8_t factor_u8, int colorspace,

                     bool incremental,

                     const fuzz_utils::WebPDecoderOptionsCpp& decoder_options) {

  WebPDecoderConfig config;

  if (!WebPInitDecoderConfig(&config)) return;

  const uint8_t* const data = reinterpret_cast<const uint8_t*>(blob.data());

  const size_t size = blob.size();

  if (WebPGetFeatures(data, size, &config.input) != VP8_STATUS_OK) return;

  if ((size_t)config.input.width * config.input.height >

      fuzz_utils::kFuzzPxLimit) {

    return;

  }

  // Using two independent criteria ensures that all combinations of options

  // can reach each path at the decoding stage, with meaningful differences.

  const uint8_t value = fuzz_utils::FuzzHash(data, size);

  const float factor = factor_u8 / 255.f;  // 0-1

  std::memcpy(&config.options, &decoder_options, sizeof(decoder_options));

  if (config.options.use_cropping) {

    config.options.crop_width = (int)(config.input.width * (1 - factor));

    config.options.crop_height = (int)(config.input.height * (1 - factor));

    config.options.crop_left = config.input.width - config.options.crop_width;

    config.options.crop_top = config.input.height - config.options.crop_height;

  }

  if (config.options.use_scaling) {

    config.options.scaled_width = (int)(config.input.width * factor * 2);

    config.options.scaled_height = (int)(config.input.height * factor * 2);

  }

  config.output.colorspace = static_cast<WEBP_CSP_MODE>(colorspace);

  for (int i = 0; i < 2; ++i) {

    if (i == 1) {

      // Use the bitstream data to generate extreme ranges for the options. An

      // alternative approach would be to use a custom corpus containing webp

      // files prepended with sizeof(config.options) zeroes to allow the fuzzer

      // to modify these independently.

      const int data_offset = 50;

      if (data_offset + sizeof(config.options) >= size) break;

      memcpy(&config.options, data + data_offset, sizeof(config.options));

      // Skip easily avoidable out-of-memory fuzzing errors.

      if (config.options.use_scaling) {

        int input_width = config.input.width;

        int input_height = config.input.height;

        if (config.options.use_cropping) {

          const int cw = config.options.crop_width;

          const int ch = config.options.crop_height;

          const int x = config.options.crop_left & ~1;

          const int y = config.options.crop_top & ~1;

          if (WebPCheckCropDimensions(input_width, input_height, x, y, cw,

                                      ch)) {

            input_width = cw;

            input_height = ch;

          }

        }

        int scaled_width = config.options.scaled_width;

        int scaled_height = config.options.scaled_height;

        if (WebPRescalerGetScaledDimensions(input_width, input_height,

                                            &scaled_width, &scaled_height)) {

          size_t fuzz_px_limit = fuzz_utils::kFuzzPxLimit;

          if (scaled_width != config.input.width ||

              scaled_height != config.input.height) {

            // Using the WebPRescalerImport internally can significantly slow

            // down the execution. Avoid timeouts due to that.

            fuzz_px_limit /= 2;

          }

          // A big output canvas can lead to out-of-memory and timeout issues,

          // but a big internal working buffer can too. Also, rescaling from a

          // very wide input image to a very tall canvas can be as slow as

          // decoding a huge number of pixels. Avoid timeouts due to these.

          const uint64_t max_num_operations =

              (uint64_t)std::max(scaled_width, config.input.width) *

              std::max(scaled_height, config.input.height);

          if (max_num_operations > fuzz_px_limit) {

            break;

          }

        }

      }

    }

    if (incremental) {

      // Decodes incrementally in chunks of increasing size.

      WebPIDecoder* idec = WebPIDecode(NULL, 0, &config);

      if (!idec) return;

      VP8StatusCode status;

      if (size & 8) {

        size_t available_size = value + 1;

        while (1) {

          if (available_size > size) available_size = size;

          status = WebPIUpdate(idec, data, available_size);

          if (status != VP8_STATUS_SUSPENDED || available_size == size) break;

          available_size *= 2;

        }

      } else {

        // WebPIAppend expects new data and its size with each call.

        // Implemented here by simply advancing the pointer into data.

        const uint8_t* new_data = data;

        size_t new_size = value + 1;

        while (1) {

          if (new_data + new_size > data + size) {

            new_size = data + size - new_data;

          }

          status = WebPIAppend(idec, new_data, new_size);

          if (status != VP8_STATUS_SUSPENDED || new_size == 0) break;

          new_data += new_size;

          new_size *= 2;

        }

      }

      WebPIDelete(idec);

    } else {

      (void)WebPDecode(data, size, &config);

    }

    WebPFreeDecBuffer(&config.output);

  }

}

}  // namespace

FUZZ_TEST(AdvancedApi, AdvancedApiTest)

    .WithDomains(fuzztest::String().WithMaxSize(fuzz_utils::kMaxWebPFileSize +

                                                1),

                 /*factor_u8=*/fuzztest::Arbitrary<uint8_t>(),

#if defined(WEBP_REDUCE_CSP)

                 fuzztest::ElementOf<int>({static_cast<int>(MODE_RGBA),

                                           static_cast<int>(MODE_BGRA),

                                           static_cast<int>(MODE_rgbA),

                                           static_cast<int>(MODE_bgrA)}),

#else

                 fuzztest::InRange<int>(0, static_cast<int>(MODE_LAST) - 1),

#endif

                 /*incremental=*/fuzztest::Arbitrary<bool>(),

                 fuzz_utils::ArbitraryValidWebPDecoderOptions());