Merge pull request #72 from trufflesuite/storage-on-tracetransaction

Return storage changes in structLogs on debug_traceTransaction, fixes #46

lib/blockchain_double.js

@@ -677,13 +677,18 @@ BlockchainDouble.prototype.processTransactionTrace = function(hash, params, call
   var tx_hash_currently_processing = "";
   var tx_currently_processing = null;
 
+  var storageStack = {
+    currentDepth: -1,
+    stack: []
+  }
+
   var returnVal = {
     gas: 0,
     returnValue: "",
     structLogs: []
   };
 
-  function step_listener(event) {
+  function step_listener(event, next) {
     // See these docs:
     // https://github.com/ethereum/go-ethereum/wiki/Management-APIs
 
@@ -715,10 +720,14 @@ BlockchainDouble.prototype.processTransactionTrace = function(hash, params, call
       stack: event.stack.map(function(item) {
         return item.toString("hex"); // non-0x prefixed.
       }),
-      storage: {} // TODO: Figure out storage
+      storage: {}
     }
 
-    returnVal.structLogs.push(structLog);
+    structLog = self.processStorageTrace(structLog, storageStack, event, function(err, structLog) {
+      if (err) return next(err)
+      returnVal.structLogs.push(structLog);
+      next()
+    });
   }
 
   function beforeTx_listener(tx) {
@@ -800,6 +809,57 @@ BlockchainDouble.prototype.processTransactionTrace = function(hash, params, call
   });
 };
 
+BlockchainDouble.prototype.processStorageTrace = function(structLog, storageStack, event, callback) {
+  var self = this;
+  var name = event.opcode.name;
+
+  var argsNum = event.opcode.in;
+  var args = event.stack.slice(-argsNum)
+    .map((arg) => to.hex(arg));
+
+  if (storageStack.currentDepth > event.depth) {
+    storageStack.pop()
+  } if (storageStack.currentDepth < event.depth) {
+    storageStack.stack.push({})
+  }
+
+  storageStack.currentDepth = event.depth;
+
+  var key;
+  var value;
+  switch(name) {
+    case 'SSTORE': 
+      key = to.rpcDataHexString(args[1], 64).replace('0x','')
+      value = to.rpcDataHexString(args[0], 64).replace('0x','')
+      // use Object.assign to prevent future steps from overwriting this step's storage values
+      structLog.storage = Object.assign({}, storageStack.stack[storageStack.currentDepth])
+
+      callback(null, structLog)
+      // assign after callback because this storage change actually takes
+      // effect _after_ this opcode executes
+      storageStack.stack[storageStack.currentDepth][key] = value;
+      break;
+    case 'SLOAD':
+      // this one's more fun, we need to get the value the contract is loading from current storage
+      key = to.rpcDataHexString(args[0], 64).replace('0x','')
+
+      self.vm.stateManager.getContractStorage(event.address, args[0], function(err, result) {
+        if (err) return callback(err);
+
+        value = to.rpcDataHexString(result, 64).replace('0x','')
+        storageStack.stack[storageStack.currentDepth][key] = value;
+        // use Object.assign to prevent future steps from overwriting this step's storage values
+        structLog.storage = Object.assign({}, storageStack.stack[storageStack.currentDepth])
+        callback(null, structLog)
+      })
+      break;
+    default:
+      // use Object.assign to prevent future steps from overwriting this step's storage values
+      structLog.storage = Object.assign({}, storageStack.stack[storageStack.currentDepth])
+      callback(null, structLog)
+  }
+};
+
 BlockchainDouble.prototype.getAccount = function(address, number, callback) {
   var self = this;
 

test/DebugContract.sol

@@ -3,8 +3,10 @@ pragma solidity ^0.4.2;
 // Changes to this file will make tests fail.
 contract DebugContract {
   uint public value = 5;
+  uint public otherValue = 5;
 
   function setValue(uint _val) {
     value = _val;
+    otherValue += _val;
   }
 }

test/debug.js

@@ -99,7 +99,9 @@ describe("Debug", function() {
 
         assert.equal(lastop.op, "STOP");
         assert.equal(lastop.gasCost, 1);
-        assert.equal(lastop.pc, 131);
+        assert.equal(lastop.pc, 141);
+        assert.equal(lastop.storage['0000000000000000000000000000000000000000000000000000000000000000'], '000000000000000000000000000000000000000000000000000000000000001a')
+        assert.equal(lastop.storage['0000000000000000000000000000000000000000000000000000000000000001'], '000000000000000000000000000000000000000000000000000000000000001f')
 
         accept();
      });