Debug past transactions in debugger.

alethzero/Main.ui

@@ -165,6 +165,7 @@
     <addaction name="paranoia"/>
     <addaction name="killBlockchain"/>
     <addaction name="inject"/>
+    <addaction name="debugStepback"/>
    </widget>
    <addaction name="menu_File"/>
    <addaction name="menu_Network"/>
@@ -1430,6 +1431,14 @@ font-family: Monospace, Ubuntu Mono, Lucida Console, Courier New</string>
     <string>&amp;Load Javascript...</string>
    </property>
   </action>
+  <action name="debugStepback">
+   <property name="text">
+    <string>Single Step &amp;Backwards</string>
+   </property>
+   <property name="shortcut">
+    <string>Shift+F10</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <customwidgets>

alethzero/MainWin.cpp

@@ -868,9 +868,25 @@ void Main::on_blocks_currentItemChanged()
 				if (tx.data.size())
 					s << eth::memDump(tx.data, 16, true);
 			}
-			s << "<br/><br/>";
+			auto st = eth::State(m_client->state().db(), m_client->blockChain(), h);
+			s << renderDiff(st.pendingDiff(txi));
 
-			s << renderDiff(eth::State(m_client->state().db(), m_client->blockChain(), h).pendingDiff(txi));
+			m_executiveState = st.fromPending(txi);
+			m_currentExecution = unique_ptr<Executive>(new Executive(m_executiveState));
+			Transaction t = st.pending()[txi];
+			auto r = t.rlp();
+
+			m_pcWarp.clear();
+			m_history.clear();
+			bool done = m_currentExecution->setup(&r);
+			if (!done)
+			{
+				for (; !done; done = m_currentExecution->go(1))
+					m_history.append(WorldState({m_currentExecution->vm().curPC(), m_currentExecution->vm().gas(), m_currentExecution->vm().stack(), m_currentExecution->vm().memory(), m_currentExecution->state().storage(m_currentExecution->ext().myAddress)}));
+				initDebugger();
+				updateDebugger();
+			}
+			m_currentExecution.reset();
 		}
 
 
@@ -1200,8 +1216,8 @@ void Main::on_debug_clicked()
 			t.receiveAddress = isCreation() ? Address() : fromString(ui->destination->currentText());
 			t.sign(s);
 			auto r = t.rlp();
-			m_currentExecution->setup(&r);
 
+			m_currentExecution->setup(&r);
 			m_pcWarp.clear();
 			m_history.clear();
 			bool ok = true;
@@ -1234,6 +1250,11 @@ void Main::on_debugStep_triggered()
 	ui->debugTimeline->setValue(ui->debugTimeline->value() + 1);
 }
 
+void Main::on_debugStepback_triggered()
+{
+	ui->debugTimeline->setValue(ui->debugTimeline->value() - 1);
+}
+
 void Main::debugFinished()
 {
 	m_pcWarp.clear();
@@ -1245,6 +1266,7 @@ void Main::debugFinished()
 	ui->debugStateInfo->setText("");
 //	ui->send->setEnabled(true);
 	ui->debugStep->setEnabled(false);
+	ui->debugStepback->setEnabled(false);
 	ui->debugPanel->setEnabled(false);
 }
 
@@ -1252,6 +1274,7 @@ void Main::initDebugger()
 {
 //	ui->send->setEnabled(false);
 	ui->debugStep->setEnabled(true);
+	ui->debugStepback->setEnabled(true);
 	ui->debugPanel->setEnabled(true);
 	ui->debugCode->setEnabled(false);
 	ui->debugTimeline->setMinimum(0);

alethzero/MainWin.h

@@ -101,6 +101,7 @@ private slots:
 	void on_quit_triggered() { close(); }
 	void on_urlEdit_returnPressed();
 	void on_debugStep_triggered();
+	void on_debugStepback_triggered();
 	void on_debug_clicked();
 	void on_debugTimeline_valueChanged();
 	void on_jsInput_returnPressed();

libethereum/Executive.cpp

@@ -40,7 +40,7 @@ u256 Executive::gasUsed() const
 	return m_t.gas - m_endGas;
 }
 
-void Executive::setup(bytesConstRef _rlp)
+bool Executive::setup(bytesConstRef _rlp)
 {
 	// Entry point for a user-executed transaction.
 	m_t = Transaction(_rlp);
@@ -95,12 +95,12 @@ void Executive::setup(bytesConstRef _rlp)
 	m_s.subBalance(m_sender, cost);
 
 	if (m_t.isCreation())
-		create(m_sender, m_t.value, m_t.gasPrice, m_t.gas - gasCost, &m_t.data, m_sender);
+		return create(m_sender, m_t.value, m_t.gasPrice, m_t.gas - gasCost, &m_t.data, m_sender);
 	else
-		call(m_t.receiveAddress, m_sender, m_t.value, m_t.gasPrice, bytesConstRef(&m_t.data), m_t.gas - gasCost, m_sender);
+		return call(m_t.receiveAddress, m_sender, m_t.value, m_t.gasPrice, bytesConstRef(&m_t.data), m_t.gas - gasCost, m_sender);
 }
 
-void Executive::call(Address _receiveAddress, Address _senderAddress, u256 _value, u256 _gasPrice, bytesConstRef _data, u256 _gas, Address _originAddress)
+bool Executive::call(Address _receiveAddress, Address _senderAddress, u256 _value, u256 _gasPrice, bytesConstRef _data, u256 _gas, Address _originAddress)
 {
 //	cnote << "Transferring" << formatBalance(_value) << "to receiver.";
 	m_s.addBalance(_receiveAddress, _value);
@@ -110,12 +110,16 @@ void Executive::call(Address _receiveAddress, Address _senderAddress, u256 _valu
 		m_vm = new VM(_gas);
 		bytes const& c = m_s.code(_receiveAddress);
 		m_ext = new ExtVM(m_s, _receiveAddress, _senderAddress, _originAddress, _value, _gasPrice, _data, &c);
+		return false;
 	}
 	else
+	{
 		m_endGas = _gas;
+		return true;
+	}
 }
 
-void Executive::create(Address _sender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _init, Address _origin)
+bool Executive::create(Address _sender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _init, Address _origin)
 {
 	m_newAddress = right160(sha3(rlpList(_sender, m_s.transactionsFrom(_sender) - 1)));
 	while (m_s.addressInUse(m_newAddress))
@@ -127,6 +131,7 @@ void Executive::create(Address _sender, u256 _endowment, u256 _gasPrice, u256 _g
 	// Execute _init.
 	m_vm = new VM(_gas);
 	m_ext = new ExtVM(m_s, m_newAddress, _sender, _origin, _endowment, _gasPrice, bytesConstRef(), _init);
+	return _init.empty();
 }
 
 bool Executive::go(uint64_t _steps)

libethereum/Executive.h

@@ -40,9 +40,9 @@ public:
 	Executive(State& _s): m_s(_s) {}
 	~Executive();
 
-	void setup(bytesConstRef _transaction);
+	bool setup(bytesConstRef _transaction);
-	void create(Address _txSender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _code, Address _originAddress);
+	bool create(Address _txSender, u256 _endowment, u256 _gasPrice, u256 _gas, bytesConstRef _code, Address _originAddress);
-	void call(Address _myAddress, Address _txSender, u256 _txValue, u256 _gasPrice, bytesConstRef _txData, u256 _gas, Address _originAddress);
+	bool call(Address _myAddress, Address _txSender, u256 _txValue, u256 _gasPrice, bytesConstRef _txData, u256 _gas, Address _originAddress);
 	bool go(uint64_t _steps = (uint64_t)-1);
 	void finalize();
 	u256 gasUsed() const;