feat: getters for ctc extradata (#204)

* feat: getters for ctc extradata

* contracts: lint fix

* contracts: fix build

Author: tynes

contracts/optimistic-ethereum/OVM/chain/OVM_CanonicalTransactionChain.sol

@@ -158,10 +158,42 @@ contract OVM_CanonicalTransactionChain is iOVM_CanonicalTransactionChain, Lib_Ad
             uint40
         )
     {
-        (, uint40 nextQueueIndex,,) = _getBatchExtraData();
+        (,uint40 nextQueueIndex,,) = _getBatchExtraData();
         return nextQueueIndex;
     }
 
+    /**
+     * Returns the timestamp of the last transaction.
+     * @return Timestamp for the last transaction.
+     */
+    function getLastTimestamp()
+        override
+        public
+        view
+        returns (
+            uint40
+        )
+    {
+        (,,uint40 lastTimestamp,) = _getBatchExtraData();
+        return lastTimestamp;
+    }
+
+    /**
+     * Returns the blocknumber of the last transaction.
+     * @return Blocknumber for the last transaction.
+     */
+    function getLastBlockNumber()
+        override
+        public
+        view
+        returns (
+            uint40
+        )
+    {
+        (,,,uint40 lastBlockNumber) = _getBatchExtraData();
+        return lastBlockNumber;
+    }
+
     /**
      * Gets the queue element at a particular index.
      * @param _index Index of the queue element to access.

contracts/optimistic-ethereum/OVM/chain/OVM_ChainStorageContainer.sol

@@ -10,9 +10,9 @@ import { iOVM_ChainStorageContainer } from "../../iOVM/chain/iOVM_ChainStorageCo
 
 /**
  * @title OVM_ChainStorageContainer
- * @dev The Chain Storage Container provides its owner contract with read, write and delete functionality. 
+ * @dev The Chain Storage Container provides its owner contract with read, write and delete functionality.
  * This provides gas efficiency gains by enabling it to overwrite storage slots which can no longer be used
- * in a fraud proof due to the fraud window having passed, and the associated chain state or 
+ * in a fraud proof due to the fraud window having passed, and the associated chain state or
  * transactions being finalized.
  * Three disctint Chain Storage Containers will be deployed on Layer 1:
  * 1. Stores transaction batches for the Canonical Transaction Chain
@@ -42,7 +42,7 @@ contract OVM_ChainStorageContainer is iOVM_ChainStorageContainer, Lib_AddressRes
     /***************
      * Constructor *
      ***************/
-    
+
     /**
      * @param _libAddressManager Address of the Address Manager.
      * @param _owner Name of the contract that owns this container (will be resolved later).
@@ -61,7 +61,7 @@ contract OVM_ChainStorageContainer is iOVM_ChainStorageContainer, Lib_AddressRes
     /**********************
      * Function Modifiers *
      **********************/
-    
+
     modifier onlyOwner() {
         require(
             msg.sender == resolve(owner),
@@ -187,7 +187,7 @@ contract OVM_ChainStorageContainer is iOVM_ChainStorageContainer, Lib_AddressRes
     {
         return buffer.get(uint40(_index));
     }
-    
+
     /**
      * @inheritdoc iOVM_ChainStorageContainer
      */
@@ -202,7 +202,7 @@ contract OVM_ChainStorageContainer is iOVM_ChainStorageContainer, Lib_AddressRes
             uint40(_index)
         );
     }
-    
+
     /**
      * @inheritdoc iOVM_ChainStorageContainer
      */

contracts/optimistic-ethereum/iOVM/chain/iOVM_CanonicalTransactionChain.sol

@@ -133,6 +133,28 @@ interface iOVM_CanonicalTransactionChain {
             Lib_OVMCodec.QueueElement memory _element
         );
 
+    /**
+     * Returns the timestamp of the last transaction.
+     * @return Timestamp for the last transaction.
+     */
+    function getLastTimestamp()
+        external
+        view
+        returns (
+            uint40
+        );
+
+    /**
+     * Returns the blocknumber of the last transaction.
+     * @return Blocknumber for the last transaction.
+     */
+    function getLastBlockNumber()
+        external
+        view
+        returns (
+            uint40
+        );
+
     /**
      * Get the number of queue elements which have not yet been included.
      * @return Number of pending queue elements.