Error propagation from NearExt::call

[ilblackdragon]

There is a TODO error right now that gets ignored, as some errors are not due to runtime and can be non deterministic. Also return value is vector which is limiting.

Instead should propagate error via state and catch in on high level.

[ailisp]

Didn't have time to start, moving to current epoch

[ailisp]

@ilblackdragon
Did an investigation today, however find it impossible to propagate error due to how openethereum is designed.
First the TODO is this one (omit uninteresting details):

impl<'a> vm::Ext for NearExt<'a> {
    fn create(
...
    ) -> Result<ContractCreateResult, TrapKind> {
        // TODO: better error propagation.
        interpreter::deploy_code(
        ...
        )
        .map_err(|_| TrapKind::Call(ActionParams::default()))
    }
}

And interpreter::deploy_code has a reasonable good structure of error types:

• could fail coz of duplicate contract
• could fail due to insufficient balance to transfer
• fail due to one of evm error, convert to near error by convert_vm_error

each above case => Err(VMLogicError::EvmError(...))

And

• success Ok(ContractCreateResult::Created(...))
• fail due to call contructor fail => Ok(ContractCreateResult::Reverted(gas_need_to_refund)

However, when interpreter::deploy_code return to Ext::create on NearExt, this has to be converted to Result<ContractCreateResult, TrapKind>, because openethereum-73b1d27a6fe08245/2662d19/ethcore/evm/src/interpreter/mod.rs, exec_instruction calls

let create_result = ext.create(
...
);

and (without change openethereum), this must be Result<ContractCreateResult, TrapKind> type and its structure is:

/// Result of externalities create function.
pub enum ContractCreateResult {
	/// Returned when creation was successfull.
	/// Contains an address of newly created contract and gas left.
	Created(Address, U256),
	/// Returned when contract creation failed.
	/// VM doesn't have to know the reason.
	Failed,
	/// Reverted with REVERT.
	Reverted(U256, ReturnData),
}
pub enum TrapKind {
	Call(ActionParams),
	Create(ActionParams, Address),
}

So there is no way to propogate well structured error in interpreter::deploy_code to Ext::create on NearExt and higher level.

[ailisp]

@nearmax, @evgenykuzyakov @ilblackdragon or @artob
Can you confirm my analysis is valid, and if so, is this worth to do in a bounty, to modify openethereum to make this error propagation becomes possible? Thanks

[stale]

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