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// 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 <stdint.h>
#include <string.h>
#include "./fuzz_utils.h"
#include "src/utils/rescaler_utils.h"
#include "src/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);
}
#if defined(WEBP_REDUCE_CSP)
config.output.colorspace = (value & 1)
? ((value & 2) ? MODE_RGBA : MODE_BGRA)
: ((value & 2) ? MODE_rgbA : MODE_bgrA);
#else
config.output.colorspace = (WEBP_CSP_MODE)(value % MODE_LAST);
#endif // WEBP_REDUCE_CSP
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 scaled_width = config.options.scaled_width;
int scaled_height = config.options.scaled_height;
if (WebPRescalerGetScaledDimensions(config.input.width,
config.input.height, &scaled_width,
&scaled_height)) {
size_t fuzz_px_limit = 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)Max(scaled_width, config.input.width) *
Max(scaled_height, config.input.height);
if (max_num_operations > fuzz_px_limit) {
break;
}
}
}
}
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;
}
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