revm: Return bytes in Create calls

[ngotchac]

In create_inner, let b = Bytes::new(); was always returned, without ever being touched. The create calls should return the deployed contract bytecode.

This might relate to #269 ?

[rakita]

It shoud return empty if everything is okay, and return something if create fails, like here:

revm/crates/revm/src/evm_impl.rs

Line 551 in 90fe01e

interpreter.return_value(),

[ngotchac]

It shoud return empty if everything is okay, and return something if create fails, like here

I'm not sure I understand why do you think that? In geth & erigon at least, an eth_call with a contract deployment input always return the deployed bytecode:

curl --data '{"method": "eth_call","params":[{"data": "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"}, "latest"],"id":1,"jsonrpc":"2.0"}' -H "Content-Type: application/json" localhost:8545

(the input being the tx input of the WETH deployment tx : https://etherscan.io/tx/0xb95343413e459a0f97461812111254163ae53467855c0d73e0f1e7c5b8442fa3)

And this actually makes sense, since every contract deployment always end with RETURN to let the EVM know where the contract code is.

This feature is super useful to know the deployed bytecode of a contract without deploying it. Or even to run some EVM code like so:

interface ERC20 {
    function balanceOf(address) external returns(uint256);
}

contract Tester {
    constructor(address[] memory tokens) {
        uint256[] memory balances = new uint256[](tokens.length);

        for (uint256 i = 0; i < tokens.length; i += 1) {
            balances[i] = ERC20(tokens[i]).balanceOf(msg.sender);
        }

        uint256 len = (tokens.length + 1) * 32;
        assembly {
            return(balances, len)
        }
    }
}

and doing an eth_call with the deployment input will return the tokens balances.

[ngotchac]

Here's the part in go-ethereum in evm that returns the deployed code BTW: https://github.com/ethereum/go-ethereum/blob/890e2efca2111c790c6d5eb55e29981816ee1fe9/core/vm/evm.go#L404-L499

[rakita]

Sorry for the confusion, I meant revm returns only error bytes, having bytecode returned is indeed desirable.
wdyt about returning it here, if exit is return_ok fetch bytes from JournledState::state and return it?

[ngotchac]

Oh right, OK I totally misunderstood aha! Why not returning them directly in create_inner though? As they are already available, without the need to re-fetch them

[rakita]

hm you are right, Bytes is just a pointer to static vec, clone is fast.

just move this code inside return_revert and _

revm/crates/revm/src/instructions/host.rs

Line 269 in 90fe01e

interpreter.return_data_buffer = return_data;

[ngotchac]

just move this code inside return_revert and _

You mean return_ok and _ ?

[rakita]

https://github.com/bluealloy/revm/pull/289/files#diff-1d478ba44ccc56e3b1142bd3723bf97f3e254c25dd18323481aedadce0803e91L549

If create reverts, it can in that case return the return data, it should be return_revert and _

But return_ok should set it to to empty bytes.

[ngotchac]

Oh right, gotcha! So yeah I fixed that, I actually only check for Revert, so it's not added for CallTooDeep or OutOfFund

[rakita]

It is best to add it to all not just for revert, and we would need to clear past return_data_buffer with interpreter.return_data_buffer = Bytes::new() if it is return_ok

FatalExternalError is panic like error, it will stop execution and propagate to initial call

[ngotchac]

All right, it's done!

[rakita]

lgtm! ty