fix(ctb): better XDM pause in MSD

Improves the pausing mechanism for the CrossDomainMessenger in the
MigrationSystemDictator.

packages/contracts-bedrock/contracts/deployment/MigrationSystemDictator.sol

@@ -49,15 +49,24 @@ contract MigrationSystemDictator is BaseSystemDictator {
     }
 
     /**
-     * @notice Pauses the system by shutting down the L1CrossDomainMessenger and clearing many
-     *         addresses inside the AddressManager.
+     * @notice Pauses the system by shutting down the L1CrossDomainMessenger and setting the
+     *         deposit halt flag to tell the Sequencer's DTL to stop accepting deposits.
      */
     function step2() external onlyOwner step(2) {
-        // Pause the L1CrossDomainMessenger
-        L1CrossDomainMessenger(config.proxyAddressConfig.l1CrossDomainMessengerProxy).pause();
+        // Temporarily brick the L1CrossDomainMessenger by setting its implementation address to
+        // address(0) which will cause the ResolvedDelegateProxy to revert. Better than pausing
+        // the L1CrossDomainMessenger via pause() because it can be easily reverted.
+        config.globalConfig.addressManager.setAddress("OVM_L1CrossDomainMessenger", address(0));
+
+        // TODO: Set the deposit halt flag.
+    }
 
-        // Remove all dead addresses from the AddressManager
-        string[18] memory deads = [
+    /**
+     * @notice Removes deprecated addresses from the AddressManager.
+     */
+    function step3() external onlyOwner step(3) {
+        // Remove all deprecated addresses from the AddressManager
+        string[18] memory deprecated = [
             "Proxy__OVM_L1CrossDomainMessenger",
             "Proxy__OVM_L1StandardBridge",
             "OVM_CanonicalTransactionChain",
@@ -78,15 +87,15 @@ contract MigrationSystemDictator is BaseSystemDictator {
             "OVM_L1MultiMessageRelayer"
         ];
 
-        for (uint256 i = 0; i < deads.length; i++) {
-            config.globalConfig.addressManager.setAddress(deads[i], address(0));
+        for (uint256 i = 0; i < deprecated.length; i++) {
+            config.globalConfig.addressManager.setAddress(deprecated[i], address(0));
         }
     }
 
     /**
      * @notice Transfers system ownership to the ProxyAdmin.
      */
-    function step3() external onlyOwner step(3) {
+    function step4() external onlyOwner step(4) {
         // Transfer ownership of the AddressManager to the ProxyAdmin.
         config.globalConfig.addressManager.transferOwnership(
             address(config.globalConfig.proxyAdmin)
@@ -101,7 +110,11 @@ contract MigrationSystemDictator is BaseSystemDictator {
     /**
      * @notice Upgrades and initializes proxy contracts.
      */
-    function step4() external onlyOwner step(4) {
+    function step5() external onlyOwner step(5) {
+        // Pause the L1CrossDomainMessenger. Now we use the real pause() function because by the
+        // time we're done here we'll have access to the unpause() function.
+        L1CrossDomainMessenger(config.proxyAddressConfig.l1CrossDomainMessengerProxy).pause();
+
         // Upgrade and initialize the L2OutputOracle.
         config.globalConfig.proxyAdmin.upgradeAndCall(
             payable(config.proxyAddressConfig.l2OutputOracleProxy),
@@ -175,7 +188,7 @@ contract MigrationSystemDictator is BaseSystemDictator {
     /**
      * @notice Unpauses the system at which point the system should be fully operational.
      */
-    function step5() external onlyOwner step(5) {
+    function step6() external onlyOwner step(6) {
         // Unpause the L1CrossDomainMessenger.
         L1CrossDomainMessenger(config.proxyAddressConfig.l1CrossDomainMessengerProxy).unpause();
     }
@@ -183,7 +196,7 @@ contract MigrationSystemDictator is BaseSystemDictator {
     /**
      * @notice Tranfers admin ownership to the final owner.
      */
-    function step6() external onlyOwner step(6) {
+    function step7() external onlyOwner step(7) {
         // Transfer ownership of the L1CrossDomainMessenger to the final owner.
         L1CrossDomainMessenger(config.proxyAddressConfig.l1CrossDomainMessengerProxy)
             .transferOwnership(config.globalConfig.finalOwner);

packages/contracts-bedrock/deploy/019-MigrationSystemDictatorSteps.ts

@@ -188,7 +188,12 @@ const deployFn: DeployFunction = async (hre) => {
       )
     },
     2: async () => {
-      await assertContractVariable(L1CrossDomainMessenger, 'paused', true)
+      assert(
+        (await AddressManager.getAddress('OVM_L1CrossDomainMessenger')) ===
+          ethers.constants.AddressZero
+      )
+    },
+    3: async () => {
       const deads = [
         'Proxy__OVM_L1CrossDomainMessenger',
         'Proxy__OVM_L1StandardBridge',
@@ -216,7 +221,7 @@ const deployFn: DeployFunction = async (hre) => {
         )
       }
     },
-    3: async () => {
+    4: async () => {
       await assertContractVariable(AddressManager, 'owner', ProxyAdmin.address)
       assert(
         (await L1StandardBridgeProxy.callStatic.getOwner({
@@ -224,7 +229,7 @@ const deployFn: DeployFunction = async (hre) => {
         })) === ProxyAdmin.address
       )
     },
-    4: async () => {
+    5: async () => {
       // Check L2OutputOracle was initialized properly.
       await assertContractVariable(
         L2OutputOracle,
@@ -279,6 +284,7 @@ const deployFn: DeployFunction = async (hre) => {
       )
 
       // Check L1CrossDomainMessenger was initialized properly.
+      await assertContractVariable(L1CrossDomainMessenger, 'paused', true)
       try {
         await L1CrossDomainMessenger.xDomainMessageSender()
         assert(false, `L1CrossDomainMessenger was not initialized properly`)
@@ -318,10 +324,10 @@ const deployFn: DeployFunction = async (hre) => {
         L1CrossDomainMessenger.address
       )
     },
-    5: async () => {
+    6: async () => {
       await assertContractVariable(L1CrossDomainMessenger, 'paused', false)
     },
-    6: async () => {
+    7: async () => {
       await assertContractVariable(
         L1CrossDomainMessenger,
         'owner',
@@ -335,7 +341,7 @@ const deployFn: DeployFunction = async (hre) => {
     },
   }
 
-  for (let i = 1; i <= 6; i++) {
+  for (let i = 1; i <= 7; i++) {
     if ((await MigrationSystemDictator.currentStep()) === i) {
       if (isLiveDeployer) {
         console.log(`Executing step ${i}...`)