ContractCodec.decodeConstructorInput strips a non-existent 4-byte selector, corrupting constructor params

[kyonRay]

Description

org.fisco.bcos.sdk.v3.codec.ContractCodec.decodeConstructorInput(abi, bin, input) returns corrupted constructor parameters.

Cause

It delegates to decodeMethodAndGetInputObject(...) → decodeMethodAndGetInputObjectByABIDefinition(...), which strips the first 4 bytes assuming a function selector:

return ContractCodecTools.decode(
        inputObject, Hex.decode(input.substring(startWithHexPrefix ? 10 : 8)), isWasm);

But constructor parameter data (the bytes after the contract bytecode) has no 4-byte function selector, so the first 4 bytes of the first parameter are discarded → wrong decode.

By contrast, decodeConstructorInputToString(...) decodes correctly — it builds the input object with ABIObjectFactory.createInputObject(...) and calls contractCodecJsonWrapper.decode(...) on the full paramsInput (no 4-byte strip).

Suggested fix

Make decodeConstructorInput decode paramsInput directly without the 4-byte substring, mirroring decodeConstructorInputToString (e.g. ContractCodecTools.decode(ABIObjectFactory.createInputObject(ctorDef), Hex.decode(paramsInput), isWasm)).

Found via

A constructor encode→decode round-trip test whose object-path result did not match the (correct) string-path result, during #947.