contracts: Read latest fork from deploy config in L2 genesis script

Author: sebastianst

packages/contracts-bedrock/scripts/Config.sol

@@ -15,12 +15,12 @@ enum OutputMode {
 
 /// @notice Enum of forks available for selection when generating genesis allocs.
 enum Fork {
+    NONE,
     DELTA,
     ECOTONE,
     FJORD
 }
 
-/// @notice Always points to the latest fork.
 Fork constant LATEST_FORK = Fork.FJORD;
 
 /// @title Config
@@ -89,6 +89,8 @@ library Config {
     }
 
     /// @notice Returns the OutputMode for genesis allocs generation.
+    ///         It reads the mode from the environment variable OUTPUT_MODE.
+    ///         If it is unset, OutputMode.ALL is returned.
     function outputMode() internal view returns (OutputMode) {
         string memory modeStr = vm.envOr("OUTPUT_MODE", string("all"));
         bytes32 modeHash = keccak256(bytes(modeStr));
@@ -104,8 +106,14 @@ library Config {
     }
 
     /// @notice Returns the latest fork to use for genesis allocs generation.
+    ///         It reads the fork from the environment variable FORK. If it is
+    ///         unset, NONE is returned.
+    ///         If set to the special value "latest", the latest fork is returned.
     function fork() internal view returns (Fork) {
-        string memory forkStr = vm.envOr("FORK", string("latest"));
+        string memory forkStr = vm.envOr("FORK", string(""));
+        if (bytes(forkStr).length == 0) {
+            return Fork.NONE;
+        }
         bytes32 forkHash = keccak256(bytes(forkStr));
         if (forkHash == keccak256(bytes("latest"))) {
             return LATEST_FORK;

packages/contracts-bedrock/scripts/DeployConfig.s.sol

@@ -7,19 +7,28 @@ import { stdJson } from "forge-std/StdJson.sol";
 import { Executables } from "scripts/Executables.sol";
 import { Process } from "scripts/libraries/Process.sol";
 import { Chains } from "scripts/Chains.sol";
+import { Fork } from "scripts/Config.sol";
 
 /// @title DeployConfig
 /// @notice Represents the configuration required to deploy the system. It is expected
 ///         to read the file from JSON. A future improvement would be to have fallback
 ///         values if they are not defined in the JSON themselves.
 contract DeployConfig is Script {
+    using stdJson for string;
+
+    /// @notice Represents an unset offset value, as opposed to 0, which denotes no-offset.
+    uint256 constant NULL_OFFSET = type(uint256).max;
+
     string internal _json;
 
     address public finalSystemOwner;
     address public superchainConfigGuardian;
     uint256 public l1ChainID;
     uint256 public l2ChainID;
     uint256 public l2BlockTime;
+    uint256 public l2GenesisDeltaTimeOffset;
+    uint256 public l2GenesisEcotoneTimeOffset;
+    uint256 public l2GenesisFjordTimeOffset;
     uint256 public maxSequencerDrift;
     uint256 public sequencerWindowSize;
     uint256 public channelTimeout;
@@ -94,6 +103,11 @@ contract DeployConfig is Script {
         l1ChainID = stdJson.readUint(_json, "$.l1ChainID");
         l2ChainID = stdJson.readUint(_json, "$.l2ChainID");
         l2BlockTime = stdJson.readUint(_json, "$.l2BlockTime");
+
+        l2GenesisDeltaTimeOffset = _readOr(_json, "$.l2GenesisDeltaTimeOffset", NULL_OFFSET);
+        l2GenesisEcotoneTimeOffset = _readOr(_json, "$.l2GenesisEcotoneTimeOffset", NULL_OFFSET);
+        l2GenesisFjordTimeOffset = _readOr(_json, "$.l2GenesisFjordTimeOffset", NULL_OFFSET);
+
         maxSequencerDrift = stdJson.readUint(_json, "$.maxSequencerDrift");
         sequencerWindowSize = stdJson.readUint(_json, "$.sequencerWindowSize");
         channelTimeout = stdJson.readUint(_json, "$.channelTimeout");
@@ -161,6 +175,17 @@ contract DeployConfig is Script {
         useInterop = _readOr(_json, "$.useInterop", false);
     }
 
+    function latestGenesisFork() public view returns (Fork) {
+        if (l2GenesisFjordTimeOffset == 0) {
+            return Fork.FJORD;
+        } else if (l2GenesisEcotoneTimeOffset == 0) {
+            return Fork.ECOTONE;
+        } else if (l2GenesisDeltaTimeOffset == 0) {
+            return Fork.DELTA;
+        }
+        revert("DeployConfig: no supported fork active at genesis");
+    }
+
     function l1StartingBlockTag() public returns (bytes32) {
         try vm.parseJsonBytes32(_json, "$.l1StartingBlockTag") returns (bytes32 tag) {
             return tag;
@@ -225,15 +250,20 @@ contract DeployConfig is Script {
     }
 
     function _readOr(string memory json, string memory key, bool defaultValue) internal view returns (bool) {
-        return vm.keyExists(json, key) ? stdJson.readBool(json, key) : defaultValue;
+        return vm.keyExistsJson(json, key) ? json.readBool(key) : defaultValue;
     }
 
     function _readOr(string memory json, string memory key, uint256 defaultValue) internal view returns (uint256) {
-        return vm.keyExists(json, key) ? stdJson.readUint(json, key) : defaultValue;
+        return (vm.keyExistsJson(json, key) && !_isNull(json, key)) ? json.readUint(key) : defaultValue;
     }
 
     function _readOr(string memory json, string memory key, address defaultValue) internal view returns (address) {
-        return vm.keyExists(json, key) ? stdJson.readAddress(json, key) : defaultValue;
+        return vm.keyExistsJson(json, key) ? json.readAddress(key) : defaultValue;
+    }
+
+    function _isNull(string memory json, string memory key) internal pure returns (bool) {
+        string memory value = json.readString(key);
+        return (keccak256(bytes(value)) == keccak256(bytes("null")));
     }
 
     function _readOr(
@@ -245,6 +275,6 @@ contract DeployConfig is Script {
         view
         returns (string memory)
     {
-        return vm.keyExists(json, key) ? stdJson.readString(json, key) : defaultValue;
+        return vm.keyExists(json, key) ? json.readString(key) : defaultValue;
     }
 }

packages/contracts-bedrock/scripts/L2Genesis.s.sol

@@ -106,7 +106,22 @@ contract L2Genesis is Deployer {
     ///         Sets the precompiles, proxies, and the implementation accounts to be `vm.dumpState`
     ///         to generate a L2 genesis alloc.
     function runWithStateDump() public {
-        runWithOptions(Config.outputMode(), Config.fork(), artifactDependencies());
+        Fork fork = Config.fork();
+        if (fork == Fork.NONE) {
+            // Will revert if no deploy config can be found either.
+            fork = latestDeployConfigGenesisFork();
+            console.log("L2Genesis: using deploy config fork: %d", uint256(fork));
+        } else {
+            console.log("L2Genesis: using env var fork: %d", uint256(fork));
+        }
+        runWithOptions(Config.outputMode(), fork, artifactDependencies());
+    }
+
+    function latestDeployConfigGenesisFork() internal returns (Fork) {
+        DeployConfig cfg =
+            DeployConfig(address(uint160(uint256(keccak256(abi.encode("optimism.deployconfig"))))));
+        cfg.read(Config.deployConfigPath());
+        return cfg.latestGenesisFork();
     }
 
     /// @notice Alias for `runWithStateDump` so that no `--sig` needs to be specified.
@@ -127,6 +142,7 @@ contract L2Genesis is Deployer {
 
     /// @notice Build the L2 genesis.
     function runWithOptions(OutputMode _mode, Fork _fork, L1Dependencies memory _l1Dependencies) public {
+        console.log("L2Genesis: outputMode: %d, fork: %d", uint256(_mode), uint256(_fork));
         vm.startPrank(deployer);
         vm.chainId(cfg.l2ChainID());