From 08074ef39739ec8f76a37fcbb0a77c7622d2dbb6 Mon Sep 17 00:00:00 2001
From: Gav Wood <gav@ethcore.io>
Date: Tue, 12 Jan 2016 17:40:34 +0100
Subject: [PATCH] Use U512s for ether cost calculation.

---
 src/error.rs       |  2 +-
 src/executive.rs   | 10 +++++-----
 src/transaction.rs | 22 +++++++++++++++-------
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 3e7d3eb6d..01618c66c 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -28,7 +28,7 @@ pub enum ExecutionError {
 	InvalidNonce { expected: U256, is: U256 },
 	/// Returned when cost of transaction (value + gas_price * gas) exceeds 
 	/// current sender balance.
-	NotEnoughCash { required: U256, is: U256 },
+	NotEnoughCash { required: U512, is: U512 },
 	/// Returned when internal evm error occurs.
 	Internal
 }
diff --git a/src/executive.rs b/src/executive.rs
index 4e829cdd5..2527209c1 100644
--- a/src/executive.rs
+++ b/src/executive.rs
@@ -123,17 +123,17 @@ impl<'a> Executive<'a> {
 
 		// TODO: we might need bigints here, or at least check overflows.
 		let balance = self.state.balance(&sender);
-		let gas_cost = t.gas * t.gas_price;
-		let total_cost = t.value + gas_cost;
+		let gas_cost = U512::from(t.gas) * U512::from(t.gas_price);
+		let total_cost = U512::from(t.value) + gas_cost;
 
 		// avoid unaffordable transactions
-		if balance < total_cost {
-			return Err(From::from(ExecutionError::NotEnoughCash { required: total_cost, is: balance }));
+		if U512::from(balance) < total_cost {
+			return Err(From::from(ExecutionError::NotEnoughCash { required: total_cost, is: U512::from(balance) }));
 		}
 
 		// NOTE: there can be no invalid transactions from this point.
 		self.state.inc_nonce(&sender);
-		self.state.sub_balance(&sender, &gas_cost);
+		self.state.sub_balance(&sender, &U256::from(gas_cost));
 
 		let mut substate = Substate::new();
 		let backup = self.state.clone();
diff --git a/src/transaction.rs b/src/transaction.rs
index 661c1355f..e67add169 100644
--- a/src/transaction.rs
+++ b/src/transaction.rs
@@ -90,25 +90,33 @@ impl Transaction {
 	/// Returns transaction sender.
 	pub fn sender(&self) -> Result<Address, Error> { Ok(From::from(try!(ec::recover(&self.signature(), &self.message_hash())).sha3())) }
 
+	/// Signs the transaction as coming from `sender`.
+	pub fn sign(&mut self, secret: &Secret) {
+		let sig = ec::sign(secret, &self.message_hash());
+		let (r, s, v) = sig.unwrap().to_rsv();
+		self.r = r;
+		self.s = s;
+		self.v = v;
+	}
+
 	/// Get the transaction cost in gas for the given params.
-	pub fn gas_required_for(is_create: bool, data: &[u8], schedule: &Schedule) -> U256 {
-		// CRITICAL TODO XXX FIX NEED BIGINT!!!!!
+	pub fn gas_required_for(is_create: bool, data: &[u8], schedule: &Schedule) -> u64 {
 		data.iter().fold(
-			U256::from(if is_create {schedule.tx_create_gas} else {schedule.tx_gas}),
-			|g, b| g + U256::from(match *b { 0 => schedule.tx_data_zero_gas, _ => schedule.tx_data_non_zero_gas})
+			(if is_create {schedule.tx_create_gas} else {schedule.tx_gas}) as u64,
+			|g, b| g + (match *b { 0 => schedule.tx_data_zero_gas, _ => schedule.tx_data_non_zero_gas }) as u64
 		)
 	}
 
 	/// Get the transaction cost in gas for this transaction.
-	pub fn gas_required(&self, schedule: &Schedule) -> U256 {
+	pub fn gas_required(&self, schedule: &Schedule) -> u64 {
 		Self::gas_required_for(match self.action{Action::Create=>true, Action::Call(_)=>false}, &self.data, schedule)
 	}
 
 	/// Do basic validation, checking for valid signature and minimum gas,
 	pub fn validate(self, schedule: &Schedule) -> Result<Transaction, Error> {
 		try!(self.sender());
-		if self.gas < self.gas_required(&schedule) {
-			Err(From::from(TransactionError::InvalidGasLimit(OutOfBounds{min: Some(self.gas_required(&schedule)), max: None, found: self.gas})))
+		if self.gas < U256::from(self.gas_required(&schedule)) {
+			Err(From::from(TransactionError::InvalidGasLimit(OutOfBounds{min: Some(U256::from(self.gas_required(&schedule))), max: None, found: self.gas})))
 		} else {
 			Ok(self)
 		}