From 27960a36de879634ee8c491d0f4fe8160e8a4f75 Mon Sep 17 00:00:00 2001
From: Gavin Andresen <gavinandresen@gmail.com>
Date: Thu, 16 Feb 2012 10:22:31 -0500
Subject: [PATCH] Fix issue #848 : broken mining on testnet

---
 src/bitcoinrpc.cpp |    4 ++--
 src/main.cpp       |   20 ++++++++++++++++++--
 src/main.h         |    2 ++
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/bitcoinrpc.cpp b/src/bitcoinrpc.cpp
index 36490e9..1f57bf9 100644
--- a/src/bitcoinrpc.cpp
+++ b/src/bitcoinrpc.cpp
@@ -1654,7 +1654,7 @@ Value getwork(const Array& params, bool fHelp)
         }
 
         // Update nTime
-        pblock->nTime = max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
+        pblock->UpdateTime(pindexPrev);
         pblock->nNonce = 0;
 
         // Update nExtraNonce
@@ -1751,7 +1751,7 @@ Value getmemorypool(const Array& params, bool fHelp)
         }
 
         // Update nTime
-        pblock->nTime = max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
+        pblock->UpdateTime(pindexPrev);
         pblock->nNonce = 0;
 
         Array transactions;
diff --git a/src/main.cpp b/src/main.cpp
index 7478054..78a7ec3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -820,6 +820,15 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
         printf("InvalidChainFound: WARNING: Displayed transactions may not be correct!  You may need to upgrade, or other nodes may need to upgrade.\n");
 }
 
+void CBlock::UpdateTime(const CBlockIndex* pindexPrev)
+{
+    nTime = max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
+
+    // Updating time can change work required on testnet:
+    if (fTestNet)
+        nBits = GetNextWorkRequired(pindexPrev, this);
+}
+
 
 
 
@@ -2949,7 +2958,7 @@ CBlock* CreateNewBlock(CReserveKey& reservekey)
     // Fill in header
     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
     pblock->hashMerkleRoot = pblock->BuildMerkleTree();
-    pblock->nTime          = max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
+    pblock->UpdateTime(pindexPrev);
     pblock->nBits          = GetNextWorkRequired(pindexPrev, pblock.get());
     pblock->nNonce         = 0;
 
@@ -3105,6 +3114,7 @@ void static BitcoinMiner(CWallet *pwallet)
         FormatHashBuffers(pblock.get(), pmidstate, pdata, phash1);
 
         unsigned int& nBlockTime = *(unsigned int*)(pdata + 64 + 4);
+        unsigned int& nBlockBits = *(unsigned int*)(pdata + 64 + 8);
         unsigned int& nBlockNonce = *(unsigned int*)(pdata + 64 + 12);
 
 
@@ -3192,8 +3202,14 @@ void static BitcoinMiner(CWallet *pwallet)
                 break;
 
             // Update nTime every few seconds
-            pblock->nTime = max(pindexPrev->GetMedianTimePast()+1, GetAdjustedTime());
+            pblock->UpdateTime(pindexPrev);
             nBlockTime = ByteReverse(pblock->nTime);
+            if (fTestNet)
+            {
+                // Changing pblock->nTime can change work required on testnet:
+                nBlockBits = ByteReverse(pblock->nBits);
+                hashTarget = CBigNum().SetCompact(pblock->nBits).getuint256();
+            }
         }
     }
 }
diff --git a/src/main.h b/src/main.h
index a1fb548..083d340 100644
--- a/src/main.h
+++ b/src/main.h
@@ -856,6 +856,8 @@ public:
         return n;
     }
 
+    void UpdateTime(const CBlockIndex* pindexPrev);
+
 
     uint256 BuildMerkleTree() const
     {
-- 
1.7.1