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json/tests/src/fuzzer-json_view_image.cpp
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Niels Lohmann 330fbead59 Document clang-tidy exclusions, drop unneeded ones, and clean up doc examples (#5909)
* Document clang-tidy exclusions and drop unneeded ones

Re-enable every excluded check in a run of clang-tidy 22 over all tests
and remove the seven that never fire (cert-err58-cpp,
clang-analyzer-webkit.NoUncountedMemberChecker,
cppcoreguidelines-virtual-class-destructor, google-readability-function-size,
hicpp-function-size, hicpp-no-assembler, readability-function-size).

Document the reason for every remaining exclusion at the top of the file.

Exclude in advance the checks that only exist in clang-tidy 23 and are
noise here (bugprone-signed-bitwise, *-explicit-constructor,
readability-trailing-comma, modernize-use-string-view), plus
modernize-use-integer-sign-comparison, which needs C++20 std::cmp_less
and flags deliberate casts.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix clang-tidy findings in documentation examples and replace redundant aliases

Apply clang-tidy fixes to the documentation examples:
- performance-avoid-endl: std::endl -> '\n'
- readability-qualified-auto: auto -> auto* / const auto*
- performance-for-range-copy: copy -> const reference
- google-readability-casting: C-style cast -> static_cast

Replace redundant aliases (readability-redundant-qualified-alias) such as
"using json = nlohmann::json;" with "using nlohmann::json;" in the
documentation, README, examples, tests, and benchmarks. Aliases at class
scope and aliases of other types (with_base_class_t etc.) are kept.

No changes to the library or its public API. All changed examples were
compiled and run; their output matches the stored .output files (except
max_size and meta, which depend on the platform and compiler).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Format doc examples with the pinned astyle

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 12:07:51 +01:00

96 lines
3.0 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 test of json_document images suitable for fuzz
testing. The input is used twice:
- as an image: json_document::load() with image_check::full must either throw
a parse_error or yield a document that serializes to the JSON text it reads
as; with image_check::bounds, reading and serializing must be safe (checked
by the sanitizers), and serializing may only throw type_error.316
- as a JSON text: if json_document::parse() accepts it, the image of the
document must load (with every check) and serialize to the same text
The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
drivers.
*/
#include <cassert>
#include <cstdint>
#include <string>
#include <vector>
#include <nlohmann/json.hpp>
#include <nlohmann/json_view.hpp>
// the checks below are assertions; NDEBUG would compile them away
#ifdef NDEBUG
#error "the fuzzer drivers must be built without NDEBUG"
#endif
using nlohmann::json;
using nlohmann::json_document;
using image_check = json_document::image_check;
// see http://llvm.org/docs/LibFuzzer.html
extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
{
// the input as an image
for (const image_check check :
{
image_check::full, image_check::bounds
})
{
json_document d;
try
{
d = json_document::load(data, size, check);
}
catch (const json::parse_error& e)
{
assert(e.id == 116);
continue;
}
std::string dumped;
try
{
dumped = d.root().dump();
}
catch (const json::type_error& e)
{
// invalid UTF-8 can only pass the bounds check
assert(check == image_check::bounds && e.id == 316);
continue;
}
const json j = d.root().materialize();
if (check == image_check::full)
{
assert(json::parse(dumped) == j);
// an image of the loaded document is the input
assert(d.save() == std::vector<std::uint8_t>(data, data + size));
}
}
// the input as a JSON text
const std::string text(reinterpret_cast<const char*>(data), size); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
const json_document parsed = json_document::parse(text, false);
if (!parsed.is_discarded())
{
const std::vector<std::uint8_t> image = parsed.save();
for (const image_check check :
{
image_check::full, image_check::bounds, image_check::none
})
{
const json_document loaded = json_document::load(image, check);
assert(loaded.root().dump() == parsed.root().dump());
}
}
return 0;
}