Refactor static context check in CREATE. (#6886)

* Refactor static context check in CREATE.

* Fix wasm.

ethcore/evm/src/interpreter/mod.rs

@@ -322,20 +322,24 @@ impl<Cost: CostType> Interpreter<Cost> {
 				let init_off = stack.pop_back();
 				let init_size = stack.pop_back();
 
-				let address_scheme = if instruction == instructions::CREATE { CreateContractAddress::FromSenderAndNonce } else { CreateContractAddress::FromSenderAndCodeHash };
 				let create_gas = provided.expect("`provided` comes through Self::exec from `Gasometer::get_gas_cost_mem`; `gas_gas_mem_cost` guarantees `Some` when instruction is `CALL`/`CALLCODE`/`DELEGATECALL`/`CREATE`; this is `CREATE`; qed");
 
-				let contract_code = self.mem.read_slice(init_off, init_size);
-				let can_create = ext.balance(&params.address)? >= endowment && ext.depth() < ext.schedule().max_depth;
+				if ext.is_static() {
+					return Err(vm::Error::MutableCallInStaticContext);
+				}
 
 				// clear return data buffer before creating new call frame.
 				self.return_data = ReturnData::empty();
 
+				let can_create = ext.balance(&params.address)? >= endowment && ext.depth() < ext.schedule().max_depth;
 				if !can_create {
 					stack.push(U256::zero());
 					return Ok(InstructionResult::UnusedGas(create_gas));
 				}
 
+				let contract_code = self.mem.read_slice(init_off, init_size);
+				let address_scheme = if instruction == instructions::CREATE { CreateContractAddress::FromSenderAndNonce } else { CreateContractAddress::FromSenderAndCodeHash };
+
 				let create_result = ext.create(&create_gas.as_u256(), &endowment, contract_code, address_scheme);
 				return match create_result {
 					ContractCreateResult::Created(address, gas_left) => {
@@ -351,9 +355,6 @@ impl<Cost: CostType> Interpreter<Cost> {
 						stack.push(U256::zero());
 						Ok(InstructionResult::Ok)
 					},
-					ContractCreateResult::FailedInStaticCall => {
-						Err(vm::Error::MutableCallInStaticContext)
-					},
 				};
 			},
 			instructions::CALL | instructions::CALLCODE | instructions::DELEGATECALL | instructions::STATICCALL => {

ethcore/evm/src/tests.rs

@@ -724,7 +724,6 @@ fn test_jumps(factory: super::Factory) {
 	assert_eq!(gas_left, U256::from(54_117));
 }
 
-
 evm_test!{test_calls: test_calls_jit, test_calls_int}
 fn test_calls(factory: super::Factory) {
 	let code = "600054602d57600160005560006000600060006050610998610100f160006000600060006050610998610100f25b".from_hex().unwrap();
@@ -769,6 +768,27 @@ fn test_calls(factory: super::Factory) {
 	assert_eq!(ext.calls.len(), 2);
 }
 
+evm_test!{test_create_in_staticcall: test_create_in_staticcall_jit, test_create_in_staticcall_int}
+fn test_create_in_staticcall(factory: super::Factory) {
+	let code = "600060006064f000".from_hex().unwrap();
+
+	let address = Address::from(0x155);
+	let mut params = ActionParams::default();
+	params.gas = U256::from(100_000);
+	params.code = Some(Arc::new(code));
+	params.address = address.clone();
+	let mut ext = FakeExt::new_byzantium();
+	ext.is_static = true;
+
+	let err = {
+		let mut vm = factory.create(params.gas);
+		test_finalize(vm.exec(params, &mut ext)).unwrap_err()
+	};
+
+	assert_eq!(err, vm::Error::MutableCallInStaticContext);
+	assert_eq!(ext.calls.len(), 0);
+}
+
 fn assert_set_contains<T : Debug + Eq + PartialEq + Hash>(set: &HashSet<T>, val: &T) {
 	let contains = set.contains(val);
 	if !contains {

ethcore/src/externalities.rs

@@ -240,7 +240,6 @@ impl<'a, T: 'a, V: 'a, B: 'a> Ext for Externalities<'a, T, V, B>
 			Ok(FinalizationResult{ gas_left, apply_state: false, return_data }) => {
 				ContractCreateResult::Reverted(gas_left, return_data)
 			},
-			Err(vm::Error::MutableCallInStaticContext) => ContractCreateResult::FailedInStaticCall,
 			_ => ContractCreateResult::Failed,
 		}
 	}

ethcore/vm/src/ext.rs

@@ -35,9 +35,6 @@ pub enum ContractCreateResult {
 	/// Returned when contract creation failed.
 	/// VM doesn't have to know the reason.
 	Failed,
-	/// Returned when contract creation failed.
-	/// VM doesn't have to know the reason.
-	FailedInStaticCall,
 	/// Reverted with REVERT.
 	Reverted(U256, ReturnData),
 }

ethcore/vm/src/tests.rs

@@ -65,6 +65,7 @@ pub struct FakeExt {
 	pub schedule: Schedule,
 	pub balances: HashMap<Address, U256>,
 	pub tracing: bool,
+	pub is_static: bool,
 }
 
 // similar to the normal `finalize` function, but ignoring NeedsReturn.
@@ -192,7 +193,7 @@ impl Ext for FakeExt {
 	}
 
 	fn is_static(&self) -> bool {
-		false
+		self.is_static
 	}
 
 	fn inc_sstore_clears(&mut self) {

ethcore/wasm/src/runtime.rs

@@ -277,10 +277,6 @@ impl<'a, 'b> Runtime<'a, 'b> {
 				self.gas_counter = self.gas_limit - gas_left.low_u64();
 				Ok(Some((-1i32).into()))
 			},
-			vm::ContractCreateResult::FailedInStaticCall => {
-				trace!(target: "wasm", "runtime: create contract called in static context");
-				Err(interpreter::Error::Trap("CREATE in static context".to_owned()))
-			},
 		}
 	}