From 3f725ce89d6e83859aba1a4f374906d0ee85e265 Mon Sep 17 00:00:00 2001
From: debris <marek.kotewicz@gmail.com>
Date: Mon, 11 Jan 2016 15:55:54 +0100
Subject: [PATCH] reverting the execution state when out of gas

---
 src/evm/executive.rs | 61 ++++++++++++++++++++++++++------------------
 src/evm/ext.rs       |  1 +
 src/evm/jit.rs       |  4 +++
 3 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/src/evm/executive.rs b/src/evm/executive.rs
index 5645f4daa..7b4b7da59 100644
--- a/src/evm/executive.rs
+++ b/src/evm/executive.rs
@@ -65,8 +65,6 @@ pub struct Executed {
 	///
 	/// where `tn` is current transaction.
 	pub cumulative_gas_used: U256,
-	/// Transaction output.
-	pub output: Bytes,
 	/// Vector of logs generated by transaction.
 	pub logs: Vec<LogEntry>
 }
@@ -78,7 +76,6 @@ impl Executed {
 			gas_used: U256::zero(),
 			refunded: U256::zero(),
 			cumulative_gas_used: U256::zero(),
-			output: vec![],
 			logs: vec![]
 		}
 	}
@@ -168,6 +165,8 @@ impl<'a> Executive<'a> {
 		self.state.inc_nonce(&sender);
 		let mut substate = Substate::new();
 
+		let backup = self.state.clone();
+
 		let res = match t.action() {
 			&Action::Create => {
 				let params = EvmParams {
@@ -198,9 +197,7 @@ impl<'a> Executive<'a> {
 		};
 
 		// finalize here!
-		self.finalize(substate, &sender, U256::zero(), U256::zero(), t.gas_price);
-		//res
-		Ok(Executed::new())
+		self.finalize(t, substate, backup, res)
 	}
 
 	/// Calls contract function with given contract params.
@@ -247,27 +244,41 @@ impl<'a> Executive<'a> {
 	}
 
 	/// Finalizes the transaction (does refunds and suicides).
-	fn finalize(&mut self, substate: Substate, sender: &Address, gas: U256, gas_left: U256, gas_price: U256) {
-		let schedule = self.engine.evm_schedule(self.info);
+	fn finalize(&mut self, t: &Transaction, substate: Substate, backup: State, result: EvmResult) -> ExecutionResult {
+		match result { 
+			Err(EvmError::Internal) => Err(ExecutionError::Internal),
+			Err(EvmError::OutOfGas) => {
+				let executed = Executed::new();
+				*self.state = backup;
+				Ok(executed)
+			},
+			Ok(gas_left) => {
+				let executed = Executed::new();
 
-		// refunds from SSTORE nonzero -> zero
-		let sstore_refunds = U256::from(schedule.sstore_refund_gas) * substate.refunds_count;
-		// refunds from contract suicides
-		let suicide_refunds = U256::from(schedule.suicide_refund_gas) * U256::from(substate.suicides.len());
+				let schedule = self.engine.evm_schedule(self.info);
 
-		// real ammount to refund
-		let refund = cmp::min(sstore_refunds + suicide_refunds, (gas - gas_left) / U256::from(2)) + gas_left;
-		let refund_value = refund * gas_price;
-		self.state.add_balance(sender, &refund_value);
-		
-		// fees earned by author
-		let fees = (gas - refund) * gas_price;
-		let author = &self.info.author;
-		self.state.add_balance(author, &fees);
+				// refunds from SSTORE nonzero -> zero
+				let sstore_refunds = U256::from(schedule.sstore_refund_gas) * substate.refunds_count;
+				// refunds from contract suicides
+				let suicide_refunds = U256::from(schedule.suicide_refund_gas) * U256::from(substate.suicides.len());
 
-		// perform suicides
-		for address in substate.suicides.iter() {
-			self.state.kill_account(address);
+				// real ammount to refund
+				let refund = cmp::min(sstore_refunds + suicide_refunds, (t.gas - gas_left) / U256::from(2)) + gas_left;
+				let refund_value = refund * t.gas_price;
+				self.state.add_balance(&t.sender(), &refund_value);
+				
+				// fees earned by author
+				let fees = (t.gas - refund) * t.gas_price;
+				let author = &self.info.author;
+				self.state.add_balance(author, &fees);
+
+				// perform suicides
+				for address in substate.suicides.iter() {
+					self.state.kill_account(address);
+				}
+
+				Ok(executed)
+			}
 		}
 	}
 }
@@ -392,7 +403,7 @@ impl<'a> Ext for Externalities<'a> {
 			return Err(EvmError::OutOfGas)
 		}
 
-		let mut gas = gas - gas_cost;
+		let gas = gas - gas_cost;
 
 		//println!("depth: {:?}", self.depth);
 		// if balance is insufficient or we are to deep, return
diff --git a/src/evm/ext.rs b/src/evm/ext.rs
index 33f89e32f..e2680ea71 100644
--- a/src/evm/ext.rs
+++ b/src/evm/ext.rs
@@ -6,6 +6,7 @@ use util::bytes::*;
 use evm_schedule::*;
 use evm::EvmError;
 
+// TODO: replace all u64 with u256
 pub trait Ext {
 	/// Returns a value for given key.
 	fn sload(&self, key: &H256) -> H256;
diff --git a/src/evm/jit.rs b/src/evm/jit.rs
index 467d871a4..d397ee77d 100644
--- a/src/evm/jit.rs
+++ b/src/evm/jit.rs
@@ -159,6 +159,10 @@ impl IntoJit<evmjit::RuntimeDataHandle> for RuntimeData {
 	}
 }
 
+/// Externalities adapter. Maps callbacks from evmjit to externalities trait.
+/// 
+/// Evmjit doesn't have to know about children execution failures. 
+/// This adapter 'catches' them and moves upstream.
 struct ExtAdapter<'a> {
 	ext: &'a mut evm::Ext,
 	err: &'a mut Option<evm::EvmError>