Niels Lohmann d2309300e9 Write and read the inner length of BSON binary subtype 0x02 ...

The BSON specification defines the payload of the "binary (old)" subtype
0x02 as an int32 followed by that many bytes. to_bson wrote the plain
payload instead, so decoders such as pymongo and libbson-based readers
rejected the bytes, and from_bson returned the inner length as part of the
payload (documented as lenient behavior in gh-5333).

The writer now emits the outer length (payload + 4), the subtype, the inner
int32 holding the payload size, and the payload. The reader requires an
outer length of at least 4 and an inner length equal to the outer length
minus 4 (the cases the bson-corpus lists as decode errors), reports parse
error 112 otherwise, and returns only the payload. Both directions change
together so that the round trip keeps working.

The single-reservation fast path for scalar entries declines subtype 0x02
because it has no room for the inner length.

This is a deliberate exception to the opt-in rule for behavior changes:
the previous output was invalid BSON.

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

2026-10-26 06:53:04 +01:00

..

binary_writer.hpp

Write and read the inner length of BSON binary subtype 0x02

2026-10-26 06:53:04 +01:00

error_handler.hpp

Add an error_handler parameter for UTF-8 to the binary readers and writers (#5746)

2026-10-04 12:13:49 +02:00

output_adapters.hpp

Write binary formats through reserved sink space and number runs (#5885)

2026-10-23 06:52:58 +02:00

serializer.hpp

Consolidate duplicated detail helpers and bodies (#5891) (#5901)

2026-10-25 06:17:50 +01:00