From 5185e6a6efb95336a16d65fa496d12eee8a91a85 Mon Sep 17 00:00:00 2001
From: Gav Wood <i@gavwood.com>
Date: Sat, 1 Feb 2014 17:37:34 +0000
Subject: [PATCH] Changed genesis block to reflect root of empty trie as null.

---
 libethereum/BlockInfo.cpp | 2 +-
 libethereum/TrieDB.cpp    | 3 +++
 libethereum/TrieDB.h      | 4 +++-
 test/main.cpp             | 4 ++--
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/libethereum/BlockInfo.cpp b/libethereum/BlockInfo.cpp
index 3f818596d..78059c42f 100644
--- a/libethereum/BlockInfo.cpp
+++ b/libethereum/BlockInfo.cpp
@@ -42,7 +42,7 @@ bytes BlockInfo::createGenesisBlock()
 {
 	RLPStream block(3);
 	auto sha3EmptyList = sha3(RLPEmptyList);
-	block.appendList(9) << h256() << sha3EmptyList << h160() << sha3(RLPNull) << sha3EmptyList << c_genesisDifficulty << (uint)0 << string() << (uint)0;
+	block.appendList(9) << h256() << sha3EmptyList << h160() << h256() << sha3EmptyList << c_genesisDifficulty << (uint)0 << string() << (uint)0;
 	block.appendRaw(RLPEmptyList);
 	block.appendRaw(RLPEmptyList);
 	return block.out();
diff --git a/libethereum/TrieDB.cpp b/libethereum/TrieDB.cpp
index d41d22434..48838474d 100644
--- a/libethereum/TrieDB.cpp
+++ b/libethereum/TrieDB.cpp
@@ -26,4 +26,7 @@ using namespace eth;
 
 namespace eth
 {
+
+const h256 c_shaNull = sha3("");
+
 }
diff --git a/libethereum/TrieDB.h b/libethereum/TrieDB.h
index c9d983cfb..2448cf8a9 100644
--- a/libethereum/TrieDB.h
+++ b/libethereum/TrieDB.h
@@ -94,6 +94,8 @@ private:
 #pragma warning(disable:4100) // disable warnings so it compiles
 #endif
 
+extern const h256 c_shaNull;
+
 /**
  * @brief Merkle Patricia Tree "Trie": a modifed base-16 Radix tree.
  * This version uses an LDB backend
@@ -111,7 +113,7 @@ public:
 	void init();
 	void setRoot(h256 _root) { m_root = _root; }
 
-	h256 root() const { return m_root; }
+	h256 root() const { return m_root == c_shaNull ? h256() : m_root; }	// patch the root in the case of the empty trie. TODO: handle this properly.
 
 	void debugPrint() {}
 
diff --git a/test/main.cpp b/test/main.cpp
index 90b784cf8..cf0ce9280 100644
--- a/test/main.cpp
+++ b/test/main.cpp
@@ -35,11 +35,11 @@ using namespace eth;
 
 int main(int argc, char** argv)
 {
-	/*RLPStream s;
+	RLPStream s;
 	BlockInfo::genesis().fillStream(s, false);
 	std::cout << RLP(s.out()) << std::endl;
 	std::cout << asHex(s.out()) << std::endl;
-	std::cout << sha3(s.out()) << std::endl;*/
+	std::cout << sha3(s.out()) << std::endl;
 
 //	hexPrefixTest();
 //	rlpTest();