mirror of
https://github.com/nlohmann/json.git
synced 2026-10-16 03:07:12 +00:00
Niels Lohmann
eb74fe2ab7
* Fuzz the streaming input adapters against the contiguous one The fast paths for contiguous input (bulk string scanning, multi-byte loads, lazy position tracking) are taken only when parsing from a pointer range; streams and non-contiguous iterators still read byte by byte. The fuzzer drivers parsed only contiguous input, so a difference between the two would ship unnoticed. check_input_adapters() in fuzzer_common.hpp reads the input through a std::istringstream, a std::list iterator range, and (on POSIX) a FILE* from fmemopen, and asserts the same value, or the same exception id, message and byte position, as for the pointer range. All seven drivers call it; the JSON driver checks parse and accept, each with and without ignore_comments. It replaces the stream check of the BON8 driver. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Rename the reader parameter to avoid a flawfinder false positive Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
124 lines
3.6 KiB
C++
124 lines
3.6 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:
|
|
|
|
- j0 = parse(data, allow_exceptions = false)
|
|
- j1 = parse(data)
|
|
- assert(j0 is discarded if parsing j1 fails, and j0 == j1 otherwise)
|
|
- s1 = serialize(j1)
|
|
- j2 = parse(s1)
|
|
- s2 = serialize(j2)
|
|
- assert(s1 == s2)
|
|
- for ignore_comments = false and true: assert(parse(data) and accept(data)
|
|
give the same result for a stream, a non-contiguous iterator range, and a
|
|
FILE* as for the pointer range)
|
|
|
|
The pointer range takes the bulk fast paths, the other input adapters read byte
|
|
by byte; see check_input_adapters().
|
|
|
|
The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
|
|
drivers.
|
|
*/
|
|
|
|
#include "fuzzer_common.hpp"
|
|
|
|
namespace
|
|
{
|
|
// json::parse and json::accept for check_input_adapters()
|
|
struct parse_json
|
|
{
|
|
bool ignore_comments;
|
|
|
|
template<typename... Args>
|
|
json operator()(Args&& ... args) const
|
|
{
|
|
return json::parse(std::forward<Args>(args)..., nullptr, true, ignore_comments);
|
|
}
|
|
};
|
|
|
|
struct accept_json
|
|
{
|
|
bool ignore_comments;
|
|
|
|
template<typename... Args>
|
|
bool operator()(Args&& ... args) const
|
|
{
|
|
return json::accept(std::forward<Args>(args)..., ignore_comments);
|
|
}
|
|
};
|
|
} // namespace
|
|
|
|
// see http://llvm.org/docs/LibFuzzer.html
|
|
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
|
|
{
|
|
// step 0: parse input without exceptions
|
|
bool noexcept_threw = false;
|
|
json const j_noexcept = parse_without_exceptions([&] { return json::parse(data, data + size, nullptr, false); }, noexcept_threw);
|
|
// whether step 1 succeeded; if not, the catch blocks below check that
|
|
// step 0 failed, too
|
|
bool parsed = false;
|
|
|
|
try
|
|
{
|
|
// step 1: parse input
|
|
json const j1 = json::parse(data, data + size);
|
|
parsed = true;
|
|
|
|
// without exceptions, the same input must give the same value
|
|
assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
|
|
|
|
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
|
|
assert(parsed || noexcept_threw || j_noexcept.is_discarded());
|
|
}
|
|
catch (const json::out_of_range&)
|
|
{
|
|
// out of range errors may happen if provided sizes are excessive
|
|
assert(parsed || noexcept_threw || j_noexcept.is_discarded());
|
|
}
|
|
|
|
// step 3: the other input adapters must read the data alike
|
|
for (const bool ignore_comments :
|
|
{
|
|
false, true
|
|
})
|
|
{
|
|
check_input_adapters(data, size, parse_json{ignore_comments});
|
|
check_input_adapters(data, size, accept_json{ignore_comments});
|
|
}
|
|
|
|
// return 0 - non-zero return values are reserved for future use
|
|
return 0;
|
|
}
|