From c0f0dd78a7356bb44fc90f2785ba42d33dd05e1f Mon Sep 17 00:00:00 2001
From: Matthias Seitz <matthias.seitz@outlook.de>
Date: Tue, 24 Sep 2024 15:39:40 +0200
Subject: [PATCH] feat: add transact function to 4788 (#11157)

---
 crates/evm/src/system_calls/eip4788.rs | 134 ++++++++++++++++---------
 1 file changed, 85 insertions(+), 49 deletions(-)

diff --git a/crates/evm/src/system_calls/eip4788.rs b/crates/evm/src/system_calls/eip4788.rs
index 79beaca695..055bfb634c 100644
--- a/crates/evm/src/system_calls/eip4788.rs
+++ b/crates/evm/src/system_calls/eip4788.rs
@@ -7,7 +7,7 @@ use reth_chainspec::{ChainSpec, EthereumHardforks};
 use reth_execution_errors::{BlockExecutionError, BlockValidationError};
 use reth_primitives::Header;
 use revm::{interpreter::Host, Database, DatabaseCommit, Evm};
-use revm_primitives::{BlockEnv, CfgEnvWithHandlerCfg, EnvWithHandlerCfg, B256};
+use revm_primitives::{BlockEnv, CfgEnvWithHandlerCfg, EnvWithHandlerCfg, ResultAndState, B256};
 
 /// Apply the [EIP-4788](https://eips.ethereum.org/EIPS/eip-4788) pre block contract call.
 ///
@@ -50,6 +50,81 @@ where
     )
 }
 
+/// Applies the pre-block call to the [EIP-4788] beacon block root contract, using the given block,
+/// [`ChainSpec`], EVM.
+///
+/// Note: this does not commit the state changes to the database, it only transact the call.
+///
+/// Returns `None` if Cancun is not active or the block is the genesis block, otherwise returns the
+/// result of the call.
+///
+/// [EIP-4788]: https://eips.ethereum.org/EIPS/eip-4788
+#[inline]
+pub fn transact_beacon_root_contract_call<EvmConfig, EXT, DB, Spec>(
+    evm_config: &EvmConfig,
+    chain_spec: &Spec,
+    block_timestamp: u64,
+    block_number: u64,
+    parent_beacon_block_root: Option<B256>,
+    evm: &mut Evm<'_, EXT, DB>,
+) -> Result<Option<ResultAndState>, BlockExecutionError>
+where
+    DB: Database + DatabaseCommit,
+    DB::Error: core::fmt::Display,
+    EvmConfig: ConfigureEvm<Header = Header>,
+    Spec: EthereumHardforks,
+{
+    if !chain_spec.is_cancun_active_at_timestamp(block_timestamp) {
+        return Ok(None)
+    }
+
+    let parent_beacon_block_root =
+        parent_beacon_block_root.ok_or(BlockValidationError::MissingParentBeaconBlockRoot)?;
+
+    // if the block number is zero (genesis block) then the parent beacon block root must
+    // be 0x0 and no system transaction may occur as per EIP-4788
+    if block_number == 0 {
+        if !parent_beacon_block_root.is_zero() {
+            return Err(BlockValidationError::CancunGenesisParentBeaconBlockRootNotZero {
+                parent_beacon_block_root,
+            }
+            .into())
+        }
+        return Ok(None)
+    }
+
+    // get previous env
+    let previous_env = Box::new(evm.context.env().clone());
+
+    // modify env for pre block call
+    evm_config.fill_tx_env_system_contract_call(
+        &mut evm.context.evm.env,
+        alloy_eips::eip4788::SYSTEM_ADDRESS,
+        BEACON_ROOTS_ADDRESS,
+        parent_beacon_block_root.0.into(),
+    );
+
+    let mut res = match evm.transact() {
+        Ok(res) => res,
+        Err(e) => {
+            evm.context.evm.env = previous_env;
+            return Err(BlockValidationError::BeaconRootContractCall {
+                parent_beacon_block_root: Box::new(parent_beacon_block_root),
+                message: e.to_string(),
+            }
+            .into())
+        }
+    };
+
+    res.state.remove(&alloy_eips::eip4788::SYSTEM_ADDRESS);
+    res.state.remove(&evm.block().coinbase);
+
+    // re-set the previous env
+    evm.context.evm.env = previous_env;
+
+    Ok(Some(res))
+}
+
 /// Applies the pre-block call to the [EIP-4788] beacon block root contract, using the given block,
 /// [`ChainSpec`], EVM.
 ///
@@ -72,55 +147,16 @@ where
     EvmConfig: ConfigureEvm<Header = Header>,
     Spec: EthereumHardforks,
 {
-    if !chain_spec.is_cancun_active_at_timestamp(block_timestamp) {
-        return Ok(())
+    if let Some(res) = transact_beacon_root_contract_call(
+        evm_config,
+        chain_spec,
+        block_timestamp,
+        block_number,
+        parent_beacon_block_root,
+        evm,
+    )? {
+        evm.context.evm.db.commit(res.state);
     }
 
-    let parent_beacon_block_root =
-        parent_beacon_block_root.ok_or(BlockValidationError::MissingParentBeaconBlockRoot)?;
-
-    // if the block number is zero (genesis block) then the parent beacon block root must
-    // be 0x0 and no system transaction may occur as per EIP-4788
-    if block_number == 0 {
-        if !parent_beacon_block_root.is_zero() {
-            return Err(BlockValidationError::CancunGenesisParentBeaconBlockRootNotZero {
-                parent_beacon_block_root,
-            }
-            .into())
-        }
-        return Ok(())
-    }
-
-    // get previous env
-    let previous_env = Box::new(evm.context.env().clone());
-
-    // modify env for pre block call
-    evm_config.fill_tx_env_system_contract_call(
-        &mut evm.context.evm.env,
-        alloy_eips::eip4788::SYSTEM_ADDRESS,
-        BEACON_ROOTS_ADDRESS,
-        parent_beacon_block_root.0.into(),
-    );
-
-    let mut state = match evm.transact() {
-        Ok(res) => res.state,
-        Err(e) => {
-            evm.context.evm.env = previous_env;
-            return Err(BlockValidationError::BeaconRootContractCall {
-                parent_beacon_block_root: Box::new(parent_beacon_block_root),
-                message: e.to_string(),
-            }
-            .into())
-        }
-    };
-
-    state.remove(&alloy_eips::eip4788::SYSTEM_ADDRESS);
-    state.remove(&evm.block().coinbase);
-
-    evm.context.evm.db.commit(state);
-
-    // re-set the previous env
-    evm.context.evm.env = previous_env;
-
     Ok(())
 }