Add Blockhash library following EIP-2935 (#5642)

Co-authored-by: Arr00 <13561405+arr00@users.noreply.github.com>
This commit is contained in:
Ernesto García
2025-04-29 16:05:27 -06:00
committed by GitHub
parent 56c07e59c4
commit 6dd191a979
7 changed files with 246 additions and 1 deletions

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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
import {Blockhash} from "../utils/Blockhash.sol";
/// @dev This mock is required for upgradeable tests to pass
contract BlockhashMock {
}

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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
/**
* @dev Library for accessing historical block hashes beyond the standard 256 block limit.
* Uses EIP-2935's history storage contract which maintains a ring buffer of the last
* 8191 block hashes in state.
*
* For blocks within the last 256 blocks, it uses the native `BLOCKHASH` opcode.
* For blocks between 257 and 8191 blocks ago, it queries the EIP-2935 history storage.
* For blocks older than 8191 or future blocks, it returns zero, matching the `BLOCKHASH` behavior.
*
* NOTE: After EIP-2935 activation, it takes 8191 blocks to completely fill the history.
* Before that, only block hashes since the fork block will be available.
*/
library Blockhash {
address internal constant HISTORY_STORAGE_ADDRESS = 0x0000F90827F1C53a10cb7A02335B175320002935;
/**
* @dev Retrieves the block hash for any historical block within the supported range.
*
* NOTE: The function gracefully handles future blocks and blocks beyond the history window
* by returning zero, consistent with the EVM's native `BLOCKHASH` behavior.
*/
function blockHash(uint256 blockNumber) internal view returns (bytes32) {
uint256 current = block.number;
uint256 distance;
unchecked {
// Can only wrap around to `current + 1` given `block.number - (2**256 - 1) = block.number + 1`
distance = current - blockNumber;
}
return distance > 256 && distance <= 8191 ? _historyStorageCall(blockNumber) : blockhash(blockNumber);
}
/// @dev Internal function to query the EIP-2935 history storage contract.
function _historyStorageCall(uint256 blockNumber) private view returns (bytes32 hash) {
assembly ("memory-safe") {
mstore(0, blockNumber) // Store the blockNumber in scratch space
// In case the history storage address is not deployed, the call will succeed
// without returndata, so the hash will be 0 just as querying `blockhash` directly.
if and(gt(returndatasize(), 0), staticcall(gas(), HISTORY_STORAGE_ADDRESS, 0, 0x20, 0, 0x20)) {
hash := mload(0)
}
}
}
}