Separate path for ext code size (#2251)

* Separate path for code size

* Actually use it for EVM

* add extcodesize to TestExt

ethcore/src/evm/ext.rs

@@ -83,6 +83,9 @@ pub trait Ext {
 	/// Returns code at given address
 	fn extcode(&self, address: &Address) -> Bytes;
 
+	/// Returns code size at given address
+	fn extcodesize(&self, address: &Address) -> usize;
+
 	/// Creates log entry with given topics and data
 	fn log(&mut self, topics: Vec<H256>, data: &[u8]);
 

ethcore/src/evm/interpreter/mod.rs

@@ -471,7 +471,7 @@ impl<Cost: CostType> Interpreter<Cost> {
 			},
 			instructions::EXTCODESIZE => {
 				let address = u256_to_address(&stack.pop_back());
-				let len = ext.extcode(&address).len();
+				let len = ext.extcodesize(&address);
 				stack.push(U256::from(len));
 			},
 			instructions::CALLDATACOPY => {

ethcore/src/evm/tests.rs

@@ -140,6 +140,10 @@ impl Ext for FakeExt {
 		self.codes.get(address).unwrap_or(&Bytes::new()).clone()
 	}
 
+	fn extcodesize(&self, address: &Address) -> usize {
+		self.codes.get(address).map(|v| v.len()).unwrap_or(0)
+	}
+
 	fn log(&mut self, topics: Vec<H256>, data: &[u8]) {
 		self.logs.push(FakeLogEntry {
 			topics: topics,

ethcore/src/externalities.rs

@@ -205,6 +205,11 @@ impl<'a, T, V> Ext for Externalities<'a, T, V> where T: 'a + Tracer, V: 'a + VMT
 		self.state.code(address).unwrap_or_else(|| vec![])
 	}
 
+	fn extcodesize(&self, address: &Address) -> usize {
+		self.state.code_size(address).unwrap_or(0)
+	}
+
+
 	#[cfg_attr(feature="dev", allow(match_ref_pats))]
 	fn ret(mut self, gas: &U256, data: &[u8]) -> evm::Result<U256>
 		where Self: Sized {

ethcore/src/json_tests/executive.rs

@@ -131,6 +131,10 @@ impl<'a, T, V> Ext for TestExt<'a, T, V> where T: Tracer, V: VMTracer {
 		self.ext.extcode(address)
 	}
 
+	fn extcodesize(&self, address: &Address) -> usize {
+		self.ext.extcodesize(address)
+	}
+
 	fn log(&mut self, topics: Vec<H256>, data: &[u8]) {
 		self.ext.log(topics, data)
 	}

ethcore/src/state/mod.rs

@@ -191,12 +191,18 @@ impl State {
 		}))
 	}
 
-	/// Mutate storage of account `a` so that it is `value` for `key`.
+	/// Get the code of account `a`.
 	pub fn code(&self, a: &Address) -> Option<Bytes> {
 		self.ensure_cached(a, true,
 			|a| a.as_ref().map_or(None, |a| a.code().map(|x| x.to_vec())))
 	}
 
+	/// Get the code size of account `a`.
+	pub fn code_size(&self, a: &Address) -> Option<usize> {
+		self.ensure_cached(a, true,
+			|a| a.as_ref().map_or(None, |a| a.code().map(|x| x.len())))
+	}
+
 	/// Add `incr` to the balance of account `a`.
 	pub fn add_balance(&mut self, a: &Address, incr: &U256) {
 		trace!(target: "state", "add_balance({}, {}): {}", a, incr, self.balance(a));