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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
This commit is contained in:
Niels Lohmann
2026-10-04 12:13:49 +02:00
committed by GitHub
parent f56b418c56
commit 73e9eae3c1
30 changed files with 1794 additions and 422 deletions

View File

@@ -4,15 +4,18 @@
#define JSON_STRICT_BINARY_UTF8 /* value */
```
When defined to `1`, the binary writers [`to_cbor`](../basic_json/to_cbor.md), [`to_ubjson`](../basic_json/to_ubjson.md),
[`to_bjdata`](../basic_json/to_bjdata.md), and [`to_bson`](../basic_json/to_bson.md) check every string value and
object key for valid UTF-8 and throw [`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) for
ill-formed UTF-8, like [`dump`](../basic_json/dump.md) does. Without it, they write the bytes unchanged.
When defined to `1`, the `error_handler` parameter of the binary writers [`to_cbor`](../basic_json/to_cbor.md),
[`to_ubjson`](../basic_json/to_ubjson.md), [`to_bjdata`](../basic_json/to_bjdata.md), and
[`to_bson`](../basic_json/to_bson.md) defaults to [`error_handler_t::strict`](../basic_json/error_handler_t.md) instead
of `error_handler_t::keep`. These writers then check every string value and object key for valid UTF-8 and throw
[`type_error.316`](../../home/exceptions.md#jsonexceptiontype_error316) for ill-formed UTF-8, like
[`dump`](../basic_json/dump.md) does. Without it, they write the bytes unchanged. An `error_handler` passed explicitly
always takes precedence.
The macro does not affect:
- [`to_msgpack`](../basic_json/to_msgpack.md): the MessagePack specification allows a `str` value to contain bytes that
are not valid UTF-8, so it always writes them unchanged.
are not valid UTF-8, so its `error_handler` always defaults to `keep`.
- [`to_bon8`](../basic_json/to_bon8.md): BON8 always checks, because the UTF-8 lead bytes mark where a string ends.
- The binary readers ([`from_cbor`](../basic_json/from_cbor.md), [`from_msgpack`](../basic_json/from_msgpack.md),
[`from_ubjson`](../basic_json/from_ubjson.md), [`from_bjdata`](../basic_json/from_bjdata.md),
@@ -33,8 +36,9 @@ The default value is `0` (disabled, the behavior of version 3.12.0 and earlier i
CBOR, UBJSON, BJData, and BSON all require strings to be UTF-8. Up to version 3.12.0, the writers did not check
this, so they could produce output that other decoders reject. Checking by default would break code that stores
other encodings (for instance ISO 8859-1) in a string and only ever writes it to a binary format, so this macro
offers the check as an opt-in ahead of version 4.0.0, where it is planned to become the default (see
other encodings (for instance ISO 8859-1) in a string and only ever writes it to a binary format. You can pass
`error_handler_t::strict` to each call, or use this macro to check by default ahead of version 4.0.0, where
`strict` is planned to become the default (see
[#5529](https://github.com/nlohmann/json/issues/5529) and [#5651](https://github.com/nlohmann/json/issues/5651)).
!!! warning "Opt-in only"