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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// A fuzzer that checks correctness of json parser/writer.
// The fuzzer input is passed through parsing twice,
// so that presumably valid json is parsed/written again.
#include <stddef.h>
#include <stdint.h>
#include <string>
#include <string_view>
#include "base/compiler_specific.h"
#include "base/containers/heap_array.h"
#include "base/containers/span.h"
#include "base/json/json_reader.h"
#include "base/json/json_writer.h"
#include "base/json/string_escape.h"
#include "base/logging.h"
#include "base/values.h"
// Entry point for libFuzzer.
// We will use the last byte of data as parsing options.
// The rest will be used as text input to the parser.
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
if (size < 2) {
return 0;
}
// SAFETY: required from fuzzer.
auto all_input = UNSAFE_BUFFERS(base::span<const uint8_t>(data, size));
// Create a copy of input buffer, as otherwise we don't catch
// overflow that touches the last byte (which is used in options).
auto input = base::HeapArray<char>::CopiedFrom(
base::as_chars(all_input.first(size - 1)));
std::string_view input_string = base::as_string_view(input.as_span());
const int options = all_input[size - 1];
auto result =
base::JSONReader::ReadAndReturnValueWithError(input_string, options);
if (!result.has_value()) {
return 0;
}
std::string parsed_output;
bool b = base::JSONWriter::Write(*result, &parsed_output);
LOG_ASSERT(b);
auto double_result =
base::JSONReader::ReadAndReturnValueWithError(parsed_output, options);
LOG_ASSERT(double_result.has_value());
std::string double_parsed_output;
bool b2 = base::JSONWriter::Write(*double_result, &double_parsed_output);
LOG_ASSERT(b2);
LOG_ASSERT(parsed_output == double_parsed_output)
<< "Parser/Writer mismatch."
<< "\nInput=" << base::GetQuotedJSONString(parsed_output)
<< "\nOutput=" << base::GetQuotedJSONString(double_parsed_output);
return 0;
}
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