From b3025a5d80e179c242c11486d392bc0fe30caa87 Mon Sep 17 00:00:00 2001
From: Ricardo Guilherme Schmidt <3esmit@gmail.com>
Date: Wed, 28 Feb 2018 01:36:48 -0300
Subject: [PATCH] add upgradable instance factory and needed architecture

---
 contracts/deploy/DelegatedCall.sol     | 35 ++++++++++++++++++++
 contracts/deploy/Factory.sol           | 45 ++++++++++++++++++++++++++
 contracts/deploy/Instance.sol          | 38 ++++++++++++++++++++++
 contracts/deploy/InstanceStorage.sol   | 15 +++++++++
 contracts/deploy/UpdatableInstance.sol | 25 ++++++++++++++
 5 files changed, 158 insertions(+)
 create mode 100644 contracts/deploy/DelegatedCall.sol
 create mode 100644 contracts/deploy/Factory.sol
 create mode 100644 contracts/deploy/Instance.sol
 create mode 100644 contracts/deploy/InstanceStorage.sol
 create mode 100644 contracts/deploy/UpdatableInstance.sol

diff --git a/contracts/deploy/DelegatedCall.sol b/contracts/deploy/DelegatedCall.sol
new file mode 100644
index 0000000..0526c76
--- /dev/null
+++ b/contracts/deploy/DelegatedCall.sol
@@ -0,0 +1,35 @@
+pragma solidity ^0.4.17;
+
+
+/**
+ * @title DelegatedCall
+ * @author Ricardo Guilherme Schmidt (Status Research & Development GmbH) 
+ * @dev Abstract contract that delegates calls by `delegated` modifier to result of `targetDelegatedCall()`
+ *      Important to avoid overwriting wrong storage pointers is that never define storage to this contract
+ */
+contract DelegatedCall {
+    /**
+     * @dev delegates the call of this function
+     */
+    modifier delegated {
+        //require successfull delegate call to remote `_target()`
+        require(targetDelegatedCall().delegatecall(msg.data)); 
+        assembly {
+            let outSize := returndatasize 
+            let outDataPtr := mload(0x40) //load memory
+            returndatacopy(outDataPtr, 0, outSize) //copy last return into pointer
+            return(outDataPtr, outSize) 
+        }
+        assert(false); //should never reach here
+        _; //never will execute local logic
+    }
+
+    /**
+     * @dev defines the address for delegation of calls
+     */
+    function targetDelegatedCall()
+        internal
+        constant
+        returns(address);
+
+}
diff --git a/contracts/deploy/Factory.sol b/contracts/deploy/Factory.sol
new file mode 100644
index 0000000..19975d5
--- /dev/null
+++ b/contracts/deploy/Factory.sol
@@ -0,0 +1,45 @@
+pragma solidity ^0.4.17;
+
+import "../common/Controlled.sol";
+
+contract Factory is Controlled {
+
+    event NewKernel(address newKernel, bytes infohash);
+
+    struct Version {
+        uint256 blockNumber;
+        uint256 timestamp;
+        address kernel;
+        bytes infohash;
+    }
+    mapping (address => uint256) versionMap;
+
+    Version[] versionLog;
+    uint256 latestUpdate;
+    address latestKernel;
+
+    function Factory(address _kernel, bytes _infohash)
+        public 
+    {
+        _setKernel(_kernel, _infohash);
+    }
+
+    function setKernel(address _kernel, bytes _infohash)
+        external 
+        onlyController
+    {
+        _setKernel(_kernel, _infohash);
+    }
+
+    function _setKernel(address _kernel, bytes _infohash) 
+        internal
+    {
+        require(_kernel != latestKernel);
+        versionMap[_kernel] = versionLog.length;
+        versionLog.push(Version({blockNumber: block.number, timestamp: block.timestamp, kernel: _kernel, infohash: _infohash}));
+        latestUpdate = block.timestamp;
+        latestKernel = _kernel;
+        NewKernel(_kernel, _infohash);
+    }
+
+}
\ No newline at end of file
diff --git a/contracts/deploy/Instance.sol b/contracts/deploy/Instance.sol
new file mode 100644
index 0000000..96c18d8
--- /dev/null
+++ b/contracts/deploy/Instance.sol
@@ -0,0 +1,38 @@
+pragma solidity ^0.4.17;
+
+import "./InstanceStorage.sol";
+import "./DelegatedCall.sol";
+
+/**
+ * @title Instance
+ * @author Ricardo Guilherme Schmidt (Status Research & Development GmbH) 
+ * @dev Contract that forward everything through delegatecall to defined kernel
+ */
+contract Instance is InstanceStorage, DelegatedCall {
+
+    function Instance(address _kernel) public {
+        kernel = _kernel;
+    }
+
+    /**
+     * @dev delegatecall everything (but declared functions) to `_target()`
+     * @notice Verify `kernel()` code to predict behavior
+     */
+    function () external delegated {
+        //all goes to kernel
+    }
+
+    /**
+     * @dev returns kernel if kernel that is configured
+     * @return kernel address
+     */
+    function targetDelegatedCall()
+        internal
+        constant
+        returns(address)
+    {
+        return kernel;
+    }
+
+
+}
\ No newline at end of file
diff --git a/contracts/deploy/InstanceStorage.sol b/contracts/deploy/InstanceStorage.sol
new file mode 100644
index 0000000..ba84f64
--- /dev/null
+++ b/contracts/deploy/InstanceStorage.sol
@@ -0,0 +1,15 @@
+pragma solidity ^0.4.17;
+
+
+/**
+ * @title InstanceStorage
+ * @author Ricardo Guilherme Schmidt (Status Research & Development GmbH) 
+ * @dev Defines kernel vars that Kernel contract share with Instance.
+ *      Important to avoid overwriting wrong storage pointers is that 
+ *      InstanceStorage should be always the first contract at heritance.
+ */
+contract InstanceStorage {    
+    // protected zone start (InstanceStorage vars)
+    address public kernel;
+    // protected zone end
+}
\ No newline at end of file
diff --git a/contracts/deploy/UpdatableInstance.sol b/contracts/deploy/UpdatableInstance.sol
new file mode 100644
index 0000000..550df8d
--- /dev/null
+++ b/contracts/deploy/UpdatableInstance.sol
@@ -0,0 +1,25 @@
+pragma solidity ^0.4.17;
+
+import "./Instance.sol";
+
+
+/**
+ * @title UpdatableInstance
+ * @author Ricardo Guilherme Schmidt (Status Research & Development GmbH) 
+ * @dev Contract that can be updated by a call from itself.
+ */
+contract UpdatableInstance is Instance {
+
+    function UpdatableInstance(address _kernel) 
+        Instance(_kernel) 
+        public
+    {
+
+    }
+    
+    function updateUpdatableInstance(address _kernel) external {
+        require(msg.sender == address(this));
+        kernel = _kernel;
+    }
+
+}
\ No newline at end of file