// 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 "fuzz.h"

#include "webp/decode.h"

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

  WebPDecoderConfig config;

  if (!WebPInitDecoderConfig(&config)) return 0;

  if (WebPGetFeatures(data, size, &config.input) != VP8_STATUS_OK) return 0;

  if ((size_t)config.input.width * config.input.height > kFuzzPxLimit) return 0;

  // 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 = FuzzHash(data, size);

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

  config.options.flip = value & 1;

  config.options.bypass_filtering = value & 2;

  config.options.no_fancy_upsampling = value & 4;

  config.options.use_threads = value & 8;

  if (size & 1) {

    config.options.use_cropping = 1;

    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 (size & 2) {

    int strength = (int)(factor * 100);

    config.options.dithering_strength = strength;

    config.options.alpha_dithering_strength = 100 - strength;

  }

  if (size & 4) {

    config.options.use_scaling = 1;

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

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

  }

  config.output.colorspace = (WEBP_CSP_MODE)(value % MODE_LAST);

  if (size % 3) {

    // Decodes incrementally in chunks of increasing size.

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

    if (!idec) return 0;

    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 {

    WebPDecode(data, size, &config);

  }

  WebPFreeDecBuffer(&config.output);

  return 0;

}