Files
json/tests/src/fuzzer-parse_json.cpp
T
Niels Lohmann 5e93415d91 Merge remote-tracking branch 'origin/develop' into claude/fix-issue-3989-db7e45
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	include/nlohmann/detail/input/lexer.hpp
#	include/nlohmann/detail/input/parser.hpp
#	single_include/nlohmann/json.hpp
#	tests/src/fuzzer-parse_json.cpp
2026-10-01 07:36:30 +02:00

88 lines
2.4 KiB
C++

// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++ (supporting code)
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
/*
This file implements a parser test suitable for fuzz testing. Given a byte
array data, it performs the following steps:
- j1 = parse(data)
- s1 = serialize(j1)
- j2 = parse(s1)
- s2 = serialize(j2)
- assert(s1 == s2)
Furthermore, it parses data with a SAX parser that recovers from every error
and checks that the events are balanced, that parsing ends, and that valid
input is parsed without errors (see #3989).
The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
drivers.
*/
#include <cassert>
#include <nlohmann/json.hpp>
// the round-trip checks below are assertions; NDEBUG would compile them away
#ifdef NDEBUG
#error "the fuzzer drivers must be built without NDEBUG"
#endif
#include "fuzzer-recovering_checker.hpp"
using json = nlohmann::json;
// see http://llvm.org/docs/LibFuzzer.html
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
{
// step 0: recover from all errors, reading from memory and from a stream
{
const auto checker = check_recovering_parse(data, size, json::input_format_t::json);
assert(checker.events <= (4 * size) + 4);
assert((checker.errors == 0) == json::accept(data, data + size));
}
try
{
// step 1: parse input
json const j1 = json::parse(data, data + size);
try
{
// step 2: round trip
// first serialization
std::string const s1 = j1.dump();
// parse serialization
json const j2 = json::parse(s1);
// second serialization
std::string const s2 = j2.dump();
// serializations must match
assert(s1 == s2);
}
catch (const json::parse_error&)
{
// parsing a JSON serialization must not fail
assert(false);
}
}
catch (const json::parse_error&)
{
// parse errors are ok, because input may be random bytes
}
catch (const json::out_of_range&)
{
// out of range errors may happen if provided sizes are excessive
}
// return 0 - non-zero return values are reserved for future use
return 0;
}