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Niels Lohmann
cc472af13f
* Check the fuzzers' UBJSON/BJData round-trip invariants in the unit tests The strongest correctness checks for the UBJSON and BJData writers lived only in the OSS-Fuzz drivers: anything from_ubjson()/from_bjdata() returns must serialize with every option combination, parse back, and re-serialize stably. Those checks only run at OSS-Fuzz, so regressions surfaced days later as external reports - the same BJData assert pair was reported five times over three years, and #5494's harness change was followed by OSS-Fuzz 563659413 within a day. Add "UBJSON round-trip invariants" and "BJData round-trip invariants" test cases that run the drivers' checks on a fixed, deterministic corpus (tests/src/round_trip_corpus.hpp): integer and float boundaries, non-finite numbers, strings, binary values, optimized containers, deep nesting, the JData annotated-array matrix, and seeded random containers. They also check two properties the drivers do not: the first round trip preserves the value, and re-serializing reproduces the exact bytes. For BJData both exclude values containing a binary value, which is read back as an array of integers unless it was written as a Draft 3 optimized binary array; this carve-out is now documented in bjdata.md. Run against the headers before #5542, the BJData test fails, including on the shape from OSS-Fuzz 563659413. Also document how OSS-Fuzz reports are handled (reference them as "OSS-Fuzz: <id>", turn the reproducer into a unit test, keep drivers and unit tests in sync) in tests/fuzzing.md, and link it from the PR template and the quality assurance page. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Add the OSS-Fuzz reproducers for 474400817 and 474480402 as unit tests Following the convention added to tests/fuzzing.md, the reproducers of the two BJData fuzzer asserts tracked since January are now unit tests: - 474400817 (assert(false)): an empty object _ArraySize_ was written as the ND-array header length, which from_bjdata() could not read back. Fixed by #5455. - 474480402 (to_bjdata(j2, false, false) == vec2): a one-byte Draft 3 binary array is written in Draft 2 mode as a uint8 array and then re-serialized with the int8 marker. This is the documented exception to byte stability, not a library bug; OSS-Fuzz closed it after #5494 relaxed the harness to value stability. The test pins the exact bytes so the exception stays deliberate. The 563659413 reproducer is already a unit test (#5542). A comment also ties the existing UBJSON excessive-count test to the timeout OSS-Fuzz reported for that shape (testcase 6347769435193344). OSS-Fuzz: 474400817 OSS-Fuzz: 474480402 Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix GCC -Weffc++ and -Wuseless-cast warnings in the round-trip corpus Initialize the atoms in the member initialization list, and drop the cast of the generator's result, which already is std::size_t on 64-bit Linux. Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>