BaseProvider getStorageAt position is not spec-compliant

Ethers Version

@ethersproject/providers 5.6.5

Search Terms

BaseProvider,getStorageAt

Describe the Problem

I came across this while trying to use provider.getStorageAt(someAddress, 0); against a fresh install of Hardhat. The fresh install evidently used Hardhat v2.9.5 that includes a change to make Hardhat network’s eth_getStorageAt spec compliant (Hardhat PR here, references spec found here). Apparently the spec requires the storage position passed into eth_getStorageAt to be a 32 byte hex string, which BaseProvider doesn’t do.

Calling getStorageAt would give this Hardhat error: InvalidArgumentsError: Errors encountered in param 1: Storage slot argument must have a length of 66 ("0x" + 32 bytes), but '0x0' has a length of 3. Eventually I tracked it down to this line: https://github.com/ethers-io/ethers.js/blob/master/packages/providers/src.ts/base-provider.ts#L1482

I was able to fix it locally by changing the hexValue(p) to hexZeroPad(p, 32). I’m happy to open a PR but I’m not sure if that’s the best place to make the change / if it totally preserves backward compatibility for other use cases.

For any passerby, downgrading Hardhat version to <= v2.9.4 seems to be a sufficient workaround for now

Code Snippet

provider.getStorageAt(someAddress, 0);
// or even
provider.getStorageAt(someAddress, '0x0000000000000000000000000000000000000000000000000000000000000000');

Contract ABI

No response

Errors

No response

Environment

node.js (v12 or newer), Hardhat

Environment (Other)

No response

[ricmoo]

5.6.7 should work too. I’ll re-open and look at it tomorrow.

[ricmoo]

The change should probably go into JsonRpcProvider for going over the JSON-RPC wire protocol, since I don’t want to change the behaviour of the the class BaseProvider which has other sub-classes.

Thanks! I’ll fix this today. 😃

(Note: in v6, the formatter has a storageSlot method, which is used to safely transform this value based on the network)