Run the CBOR, MessagePack, BSON and BON8 round-trip invariants in CI

tests/src/round_trip_corpus.hpp exists so that the byte-stability
invariant the fuzzer drivers check also runs on a fixed corpus in CI,
instead of only at OSS-Fuzz. So far only the UBJSON and BJData drivers
had a matching unit test; the CBOR, MessagePack, BSON and BON8 drivers
assert the same invariant (assert(to_X(j2) == vec)) but nothing ran it
outside OSS-Fuzz.

Add "<FORMAT> round-trip invariants" test cases to unit-cbor.cpp,
unit-msgpack.cpp, unit-bson.cpp and unit-bon8.cpp, modeled on the
UBJSON case: seed j1 from the corpus (skipping values that do not
survive the format's own round trip, as the fuzzer drivers only ever
see values from_X() actually produced), then require from_X(to_X(j1))
not to throw and check to_X(j2) == to_X(j1). BSON only serializes
objects, so non-object corpus values are skipped. Update the comments
in round_trip_corpus.hpp and tests/fuzzing.md to name all six formats.

The stream-versus-contiguous check in the BON8 driver is left out, as
#5601 reworks it.

A local probe confirms no violations on the current corpus (CBOR 3849
checked, MessagePack 3909, BSON 2958, BON8 3841 - matching the counts
already recorded for this probe in the issue).

Closes #5714 item 1.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-09-30 18:01:35 +02:00
parent 7dc1bc9e18
commit fbe05f2ed0
6 changed files with 151 additions and 9 deletions
+4 -3
View File
@@ -93,9 +93,10 @@ conventions:
add it as a regression test to the unit test of the affected format (e.g., `tests/src/unit-bjdata.cpp`), with a
comment naming the OSS-Fuzz issue. This way the input is checked by every CI run rather than only by OSS-Fuzz, and
it stays covered even if OSS-Fuzz later closes the report as not reproducible.
- **Keep the fuzzer drivers and the unit tests in sync.** The round-trip checks of the UBJSON and BJData drivers are
also run on a fixed corpus in the unit tests (see `tests/src/round_trip_corpus.hpp` and the "round-trip invariants"
test cases), so a regression shows up in CI first. When a driver's checks change, change the unit tests with them.
- **Keep the fuzzer drivers and the unit tests in sync.** The round-trip checks of the BJData, BON8, BSON, CBOR,
MessagePack and UBJSON drivers are also run on a fixed corpus in the unit tests (see
`tests/src/round_trip_corpus.hpp` and the "round-trip invariants" test cases), so a regression shows up in CI
first. When a driver's checks change, change the unit tests with them.
- **Record in the report whether the bug shipped.** OSS-Fuzz asks whether a crash was a short-lived regression or
affects a released version; answer it when the fix is merged, as it decides whether the fix needs a release note or
a security advisory (see the [security policy](../.github/SECURITY.md)).