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Add blockhash to docs (#5653)

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Co-authored-by: ernestognw <ernestognw@gmail.com>
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Arr00
2025-04-29 19:04:32 -04:00
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commit 3e75ff1862
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1
contracts/utils/Blockhash.sol
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@ -14,6 +14,7 @@ pragma solidity ^0.8.20;
* Before that, only block hashes since the fork block will be available. * Before that, only block hashes since the fork block will be available.
*/ */
library Blockhash { library Blockhash {
/// @dev Address of the EIP-2935 history storage contract.
address internal constant HISTORY_STORAGE_ADDRESS = 0x0000F90827F1C53a10cb7A02335B175320002935; address internal constant HISTORY_STORAGE_ADDRESS = 0x0000F90827F1C53a10cb7A02335B175320002935;
/** /**

3
contracts/utils/README.adoc
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@ -45,6 +45,7 @@ Miscellaneous contracts and libraries containing utility functions you can use t
* {Panic}: A library to revert with https://docs.soliditylang.org/en/v0.8.20/control-structures.html#panic-via-assert-and-error-via-require[Solidity panic codes]. * {Panic}: A library to revert with https://docs.soliditylang.org/en/v0.8.20/control-structures.html#panic-via-assert-and-error-via-require[Solidity panic codes].
* {Comparators}: A library that contains comparator functions to use with the {Heap} library. * {Comparators}: A library that contains comparator functions to use with the {Heap} library.
* {CAIP2}, {CAIP10}: Libraries for formatting and parsing CAIP-2 and CAIP-10 identifiers. * {CAIP2}, {CAIP10}: Libraries for formatting and parsing CAIP-2 and CAIP-10 identifiers.
* {Blockhash}: A library for accessing historical block hashes beyond the standard 256 block limit utilizing EIP-2935's historical blockhash functionality.
[NOTE] [NOTE]
==== ====
@ -156,3 +157,5 @@ Ethereum contracts have no native concept of an interface, so applications must
{{CAIP2}} {{CAIP2}}
{{CAIP10}} {{CAIP10}}
{{Blockhash}}

19
docs/modules/ROOT/pages/utilities.adoc
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@ -386,3 +386,22 @@ await instance.multicall([
instance.interface.encodeFunctionData("bar") instance.interface.encodeFunctionData("bar")
]); ]);
---- ----
=== Historical Block Hashes
xref:api:utils.adoc#Blockhash[`Blockhash`] provides L2 protocol developers with extended access to historical block hashes beyond Ethereum's native 256-block limit. By leveraging https://eips.ethereum.org/EIPS/eip-2935[EIP-2935]'s history storage contract, the library enables access to block hashes up to 8,191 blocks in the past, making it invaluable for L2 fraud proofs and state verification systems.
The library seamlessly combines native `BLOCKHASH` opcode access for recent blocks (≤256) with EIP-2935 history storage queries for older blocks (257-8,191). It handles edge cases gracefully by returning zero for future blocks or those beyond the history window, matching the EVM's behavior. The implementation uses gas-efficient assembly for static calls to the history storage contract.
[source,solidity]
----
contract L1Inbox {
using Blockhash for uint256;
function verifyBlockHash(uint256 blockNumber, bytes32 expectedHash) public view returns (bool) {
return blockNumber.blockHash() == expectedHash;
}
}
----
IMPORTANT: After EIP-2935 activation, it takes 8,191 blocks to completely fill the history storage. Before that, only block hashes since the fork block will be available.