Return an error instead of throwing on invalid UTF-8 in deserialisation helpers#1249
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palas wants to merge 3 commits into
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Return an error instead of throwing on invalid UTF-8 in deserialisation helpers#1249palas wants to merge 3 commits into
palas wants to merge 3 commits into
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palas
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Pull request overview
This PR hardens Cardano API deserialisation helpers by avoiding Text.decodeUtf8’s impure exception on invalid UTF-8, ensuring these helpers return normal decoding errors instead of crashing.
Changes:
- Switched Bech32 deserialisation paths in
deserialiseInput/deserialiseInputAnyOfto useText.decodeUtf8'and treat invalid UTF-8 as a format mismatch. - Updated
deserialiseAnyVerificationKeyBech32to avoid throwing on invalid UTF-8 and return a decoding error instead. - Added a Herald changelog fragment documenting the bugfix.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
| cardano-api/src/Cardano/Api/Serialise/DeserialiseAnyOf.hs | Avoids impure exceptions by using decodeUtf8' and mapping invalid UTF-8 to Bech32 format mismatch. |
| cardano-api/src/Cardano/Api/Key/Internal/SomeAddressVerificationKey.hs | Prevents invalid UTF-8 from throwing during Bech32 verification key deserialisation. |
| .changes/20260708_140000_cardano-api_pablo.lamela_nonthrowing_utf8_decode.yml | Changelog fragment describing the bugfix behavior change. |
carbolymer
reviewed
Jul 9, 2026
carbolymer
approved these changes
Jul 9, 2026
Jimbo4350
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Jul 9, 2026
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We shouldn't throw away the UnicodeException error. It needs to be rendered.
Instead of discarding the UnicodeException and fabricating StringToDecodeContainsInvalidChars [], deserialiseAnyVerificationKeyBech32 now returns Bech32InvalidUtf8 carrying the rendered decoding error.
Restructure the bech32 branches of deserialiseInput and deserialiseInputAnyOf as suggested in review.
carbolymer
reviewed
Jul 13, 2026
| -- ^ Unexpected header | ||
| | -- | The input is not valid UTF-8, so it cannot be a Bech32-encoded | ||
| -- string. The field contains the rendered UTF-8 decoding error. | ||
| Bech32InvalidUtf8 !Text |
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Why the field is Text and not the exception itself? I'd suggest moving of rendering of the exception to Pretty instance instead of keeping it in two places.
Jimbo4350
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2 comments to address.
| -- The input was not valid UTF-8, so it cannot be valid Bech32. | ||
| decodeText = | ||
| first (const DeserialiseInputErrorFormatMismatch) | ||
| . Text.decodeUtf8' |
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We are still throwing away the exception error here.
| deserialiseBech32 = either id fromBech32 $ decodeText inputBs | ||
| where | ||
| -- The input was not valid UTF-8, so it cannot be valid Bech32. | ||
| decodeText = |
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We are still throwing away the exception error here.
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Context
deserialiseInput,deserialiseInputAnyOfanddeserialiseAnyVerificationKeyBech32(and therebydeserialiseAnyVerificationKey) usedText.decodeUtf8, which throws an impure exception when the input is not valid UTF-8. For example,deserialiseInputon the bytes"\xc3\x28"threw instead of returningLeft InputInvalidError.This PR switches them to
Text.decodeUtf8'and treats invalid UTF-8 as a normal decoding failure.How to trust this PR
DeserialiseInputErrorFormatMismatch/Bech32DecodingError) does not change behaviour for any valid input.Rightcase ofdecodeUtf8'.Checklist
.changes/