Add initial StateTransitioner & FraudProver

packages/rollup-contracts/contracts/ExecutionManager.sol

@@ -96,6 +96,14 @@ contract ExecutionManager {
         // TODO
     }
 
+    /**
+     * @notice Sets a new state manager to be associated with the execution manager.
+     * This is used when we want to swap out a new backend to be used for a different execution.
+     */
+    function setStateManager(address _stateManagerAddress) external {
+        stateManager = FullStateManager(_stateManagerAddress);
+    }
+
     /**
      * @notice Increments the provided address's nonce.
      * This is only used by the sequencer to correct nonces when transactions fail.
@@ -582,8 +590,7 @@ contract ExecutionManager {
             restoreContractContext(oldMsgSender, oldActiveContract);
             return false;
         }
-        // Associate the code contract with our ovm contract
-        stateManager.associateCodeContract(_newOvmContractAddress, codeContractAddress);
+        // TODO: Replace `getCodeContractBytecode(...) with `getOvmContractBytecode(...)
         bytes memory codeContractBytecode = stateManager.getCodeContractBytecode(codeContractAddress);
         // Get the code contract address to be emitted by a CreatedContract event
         bytes32 codeContractHash = keccak256(codeContractBytecode);
@@ -894,6 +901,7 @@ contract ExecutionManager {
         address _targetOvmContractAddress = address(bytes20(_targetAddressBytes));
         address codeContractAddress = stateManager.getCodeContractAddress(_targetOvmContractAddress);
 
+        // TODO: Replace `getCodeContractHash(...) with `getOvmContractHash(...)
         bytes32 hash = stateManager.getCodeContractHash(codeContractAddress);
 
         assembly {

packages/rollup-contracts/contracts/FullStateManager.sol

@@ -104,7 +104,7 @@ contract FullStateManager is StateManager {
      * @param _ovmContractAddress The address of the OVM contract we'd like to associate with some code.
      * @param _codeContractAddress The address of the code contract that's been deployed.
      */
-    function associateCodeContract(address _ovmContractAddress, address _codeContractAddress) external {
+    function associateCodeContract(address _ovmContractAddress, address _codeContractAddress) public {
         ovmCodeContracts[_ovmContractAddress] = _codeContractAddress;
     }
 
@@ -183,6 +183,10 @@ contract FullStateManager is StateManager {
             // Contract runtime bytecode is not pure.
             return ZERO_ADDRESS;
         }
+
+        // Associate the code contract with our ovm contract
+        associateCodeContract(_newOvmContractAddress, codeContractAddress);
+
         return codeContractAddress;
     }
 }

packages/rollup-contracts/contracts/StateManager.sol

@@ -17,7 +17,7 @@ contract StateManager {
 
     // Contract code storage / contract address retrieval
     function deployContract(address _newOvmContractAddress, bytes memory _ovmContractInitcode) public returns(address codeContractAddress);
-    function associateCodeContract(address _ovmContractAddress, address _codeContractAddress) external;
+    function associateCodeContract(address _ovmContractAddress, address _codeContractAddress) public;
     function getCodeContractAddress(address _ovmContractAddress) external view returns(address);
     function getCodeContractBytecode(address _codeContractAddress) public view returns (bytes memory codeContractBytecode);
     function getCodeContractHash(address _codeContractAddress) external view returns (bytes32 _codeContractHash);

packages/rollup-contracts/contracts/ovm/FraudVerifier.sol

@@ -0,0 +1,27 @@
+pragma solidity ^0.5.0;
+
+import {StateTransitioner} from "./StateTransitioner.sol";
+
+/**
+ * @title FraudVerifier
+ * @notice The contract which is able to delete invalid state roots.
+ */
+contract FraudVerifier {
+    mapping(uint=>StateTransitioner) stateTransitioners;
+
+    function initNewStateTransitioner(uint _preStateTransitionIndex) public returns(bool) {
+        // TODO:
+        // Create a new state transitioner for some specific pre-state transition index (assuming one hasn't already been made).
+        // Note that the invalid state root that we are verifying is at _preStateTransitionIndex+1.
+        // Add it to the stateTransitioners mapping! -- stateTransitioners[_preStateTransitionIndex] = newStateTransitioner;
+        return true;
+    }
+
+
+    function verifyFraud(uint _transitionIndex) public returns(bool) {
+        // TODO:
+        // Simply verify that the state transitioner has completed, and that the state root
+        // at _preStateTransitionIndex+1 is not equal to the state root which was committed for that index.
+        return true;
+    }
+}