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https://github.com/nlohmann/json.git
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Niels Lohmann
43a346cf99
- copy the valid UTF-8 of a string in one step when the input is contiguous (twitter.json is read in 1.68 instead of 2.52 ms, jeopardy.json in 196 instead of 297 ms, close to CBOR and MessagePack) - share the new valid_utf8_prefix() with the writer's UTF-8 check, which now skips ASCII 8 bytes at a time - let the fuzzer check that contiguous and stream input give the same value or error, and test both paths in the unit tests - clarify that a second 0xFF after a string is an empty string Signed-off-by: Niels Lohmann <mail@nlohmann.me>
104 lines
2.8 KiB
C++
104 lines
2.8 KiB
C++
// __ _____ _____ _____
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// __| | __| | | | JSON for Modern C++ (supporting code)
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// | | |__ | | | | | | version 3.12.0
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// |_____|_____|_____|_|___| https://github.com/nlohmann/json
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//
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// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
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// SPDX-License-Identifier: MIT
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/*
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This file implements a parser test suitable for fuzz testing. Given a byte
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array data, it performs the following steps:
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- j1 = from_bon8(data)
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- vec = to_bon8(j1)
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- j2 = from_bon8(vec)
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- assert(j1 == j2)
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It also checks that reading the data from a stream, which reads strings byte by
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byte, gives the same value or error as reading it from contiguous memory, which
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copies strings in bulk.
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The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
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drivers.
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*/
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#include <cassert>
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#include <iostream>
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#include <sstream>
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#include <nlohmann/json.hpp>
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// the round-trip checks below are assertions; NDEBUG would compile them away
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#ifdef NDEBUG
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#error "the fuzzer drivers must be built without NDEBUG"
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#endif
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using json = nlohmann::json;
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namespace
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{
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// the serialization of the value read from @a input, or the error message
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template<typename InputType>
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std::string read_bon8(InputType&& input)
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{
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try
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{
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const auto vec = json::to_bon8(json::from_bon8(std::forward<InputType>(input)));
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return {vec.begin(), vec.end()};
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}
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catch (const json::exception& e)
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{
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return e.what();
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}
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}
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} // namespace
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// see http://llvm.org/docs/LibFuzzer.html
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
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{
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// contiguous and stream input must be read alike
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{
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std::istringstream stream(std::string(reinterpret_cast<const char*>(data), size));
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assert(read_bon8(std::vector<uint8_t>(data, data + size)) == read_bon8(stream));
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}
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try
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{
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// step 1: parse input
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std::vector<uint8_t> const vec1(data, data + size);
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json const j1 = json::from_bon8(vec1);
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try
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{
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// step 2: round trip
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std::vector<uint8_t> const vec2 = json::to_bon8(j1);
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// parse serialization
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json const j2 = json::from_bon8(vec2);
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// serializations must match
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assert(json::to_bon8(j2) == vec2);
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}
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catch (const json::parse_error&)
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{
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// parsing a BON8 serialization must not fail
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assert(false);
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}
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}
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catch (const json::parse_error&)
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{
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// parse errors are ok, because input may be random bytes
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}
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catch (const json::type_error&)
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{
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// type errors can occur during parsing, too
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}
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catch (const json::out_of_range&)
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{
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// out of range errors may happen if provided sizes are excessive
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}
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// return 0 - non-zero return values are reserved for future use
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return 0;
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}
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