Merge pull request #1943 from sipa/reindex2

Add -reindex, to perform in-place reindexing of block chain files

12 files changed, 405 insertions, 148 deletions

diff --git a/src/init.cpp b/src/init.cpp
index 8670ca9d39..ee7c5c5fc4 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -293,6 +293,7 @@ std::string HelpMessage()
         "  -checkblocks=<n>       " + _("How many blocks to check at startup (default: 2500, 0 = all)") + "\n" +
         "  -checklevel=<n>        " + _("How thorough the block verification is (0-6, default: 1)") + "\n" +
         "  -loadblock=<file>      " + _("Imports blocks from external blk000?.dat file") + "\n" +
+        "  -reindex               " + _("Rebuild blockchain index from current blk000??.dat files") + "\n" +
 
         "\n" + _("Block creation options:") + "\n" +
         "  -blockminsize=<n>      "   + _("Set minimum block size in bytes (default: 0)") + "\n" +
@@ -309,6 +310,82 @@ std::string HelpMessage()
 }
 
 
+struct CImportingNow
+{
+    CImportingNow() {
+        assert(fImporting == false);
+        fImporting = true;
+    }
+
+    ~CImportingNow() {
+        assert(fImporting == true);
+        fImporting = false;
+    }
+};
+
+struct CImportData {
+    std::vector<boost::filesystem::path> vFiles;
+};
+
+void ThreadImport(void *data) {
+    CImportData *import = reinterpret_cast<CImportData*>(data);
+
+    RenameThread("bitcoin-loadblk");
+
+    vnThreadsRunning[THREAD_IMPORT]++;
+
+    // -reindex
+    if (fReindex) {
+        CImportingNow imp;
+        int nFile = 0;
+        while (!fShutdown) {
+            CDiskBlockPos pos;
+            pos.nFile = nFile;
+            pos.nPos = 0;
+            FILE *file = OpenBlockFile(pos, true);
+            if (!file)
+                break;
+            printf("Reindexing block file blk%05u.dat...\n", (unsigned int)nFile);
+            LoadExternalBlockFile(file, &pos);
+            nFile++;
+        }
+        if (!fShutdown) {
+            pblocktree->WriteReindexing(false);
+            fReindex = false;
+            printf("Reindexing finished\n");
+        }
+    }
+
+    // hardcoded $DATADIR/bootstrap.dat
+    filesystem::path pathBootstrap = GetDataDir() / "bootstrap.dat";
+    if (filesystem::exists(pathBootstrap) && !fShutdown) {
+        FILE *file = fopen(pathBootstrap.string().c_str(), "rb");
+        if (file) {
+            CImportingNow imp;
+            filesystem::path pathBootstrapOld = GetDataDir() / "bootstrap.dat.old";
+            printf("Importing bootstrap.dat...\n");
+            LoadExternalBlockFile(file);
+            RenameOver(pathBootstrap, pathBootstrapOld);
+        }
+    }
+
+    // -loadblock=
+    BOOST_FOREACH(boost::filesystem::path &path, import->vFiles) {
+        if (fShutdown)
+            break;
+        FILE *file = fopen(path.string().c_str(), "rb");
+        if (file) {
+            CImportingNow imp;
+            printf("Importing %s...\n", path.string().c_str());
+            LoadExternalBlockFile(file);
+        }
+    }
+
+    delete import;
+
+    vnThreadsRunning[THREAD_IMPORT]--;
+}
+
 /** Initialize bitcoin.
  *  @pre Parameters should be parsed and config file should be read.
  */
@@ -639,6 +716,8 @@ bool AppInit2()
 
     // ********************************************************* Step 7: load block chain
 
+    fReindex = GetBoolArg("-reindex");
+
     if (!bitdb.Open(GetDataDir()))
     {
         string msg = strprintf(_("Error initializing database environment %s!"
@@ -662,10 +741,13 @@ bool AppInit2()
     uiInterface.InitMessage(_("Loading block index..."));
     printf("Loading block index...\n");
     nStart = GetTimeMillis();
-    pblocktree = new CBlockTreeDB(nBlockTreeDBCache);
-    pcoinsdbview = new CCoinsViewDB(nCoinDBCache);
+    pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReindex);
+    pcoinsdbview = new CCoinsViewDB(nCoinDBCache, false, fReindex);
     pcoinsTip = new CCoinsViewCache(*pcoinsdbview);
 
+    if (fReindex)
+        pblocktree->WriteReindexing(true);
+
     if (!LoadBlockIndex())
         return InitError(_("Error loading blkindex.dat"));
 
@@ -798,13 +880,13 @@ bool AppInit2()
     if (!ConnectBestBlock())
         strErrors << "Failed to connect best block";
 
-    std::vector<boost::filesystem::path> *vPath = new std::vector<boost::filesystem::path>();
+    CImportData *pimport = new CImportData();
     if (mapArgs.count("-loadblock"))
     {
         BOOST_FOREACH(string strFile, mapMultiArgs["-loadblock"])
-            vPath->push_back(strFile);
+            pimport->vFiles.push_back(strFile);
     }
-    NewThread(ThreadImport, vPath);
+    NewThread(ThreadImport, pimport);
 
     // ********************************************************* Step 10: load peers
 
diff --git a/src/leveldb.cpp b/src/leveldb.cpp
index 58b75e5295..9e2f32a171 100644
--- a/src/leveldb.cpp
+++ b/src/leveldb.cpp
@@ -21,7 +21,7 @@ static leveldb::Options GetOptions(size_t nCacheSize) {
     return options;
 }
 
-CLevelDB::CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool fMemory) {
+CLevelDB::CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool fMemory, bool fWipe) {
     penv = NULL;
     readoptions.verify_checksums = true;
     iteroptions.verify_checksums = true;
@@ -33,6 +33,10 @@ CLevelDB::CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool
         penv = leveldb::NewMemEnv(leveldb::Env::Default());
         options.env = penv;
     } else {
+        if (fWipe) {
+            printf("Wiping LevelDB in %s\n", path.string().c_str());
+            leveldb::DestroyDB(path.string(), options);
+        }
         boost::filesystem::create_directory(path);
         printf("Opening LevelDB in %s\n", path.string().c_str());
     }
diff --git a/src/leveldb.h b/src/leveldb.h
index e5b2e1ef0b..0b83432072 100644
--- a/src/leveldb.h
+++ b/src/leveldb.h
@@ -69,7 +69,7 @@ private:
     leveldb::DB *pdb;
 
 public:
-    CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool fMemory = false);
+    CLevelDB(const boost::filesystem::path &path, size_t nCacheSize, bool fMemory = false, bool fWipe = false);
     ~CLevelDB();
 
     template<typename K, typename V> bool Read(const K& key, V& value) {
diff --git a/src/main.cpp b/src/main.cpp
index a08e393caa..0940260f9e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,6 +41,7 @@ CBlockIndex* pindexBest = NULL;
 set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexValid; // may contain all CBlockIndex*'s that have validness >=BLOCK_VALID_TRANSACTIONS, and must contain those who aren't failed
 int64 nTimeBestReceived = 0;
 bool fImporting = false;
+bool fReindex = false;
 unsigned int nCoinCacheSize = 5000;
 
 CMedianFilter<int> cPeerBlockCounts(5, 0); // Amount of blocks that other nodes claim to have
@@ -1145,7 +1146,7 @@ int GetNumBlocksOfPeers()
 
 bool IsInitialBlockDownload()
 {
-    if (pindexBest == NULL || nBestHeight < Checkpoints::GetTotalBlocksEstimate())
+    if (pindexBest == NULL || nBestHeight < Checkpoints::GetTotalBlocksEstimate() || fReindex || fImporting)
         return true;
     static int64 nLastUpdate;
     static CBlockIndex* pindexLastBest;
@@ -1862,35 +1863,45 @@ bool CBlock::AddToBlockIndex(const CDiskBlockPos &pos)
 }
 
 
-bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64 nTime)
+bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64 nTime, bool fKnown = false)
 {
     bool fUpdatedLast = false;
 
     LOCK(cs_LastBlockFile);
 
-    while (infoLastBlockFile.nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
-        printf("Leaving block file %i: %s\n", nLastBlockFile, infoLastBlockFile.ToString().c_str());
-        FlushBlockFile();
-        nLastBlockFile++;
-        infoLastBlockFile.SetNull();
-        pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile); // check whether data for the new file somehow already exist; can fail just fine
-        fUpdatedLast = true;
+    if (fKnown) {
+        if (nLastBlockFile != pos.nFile) {
+            nLastBlockFile = pos.nFile;
+            infoLastBlockFile.SetNull();
+            pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile);
+        }
+    } else {
+        while (infoLastBlockFile.nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
+            printf("Leaving block file %i: %s\n", nLastBlockFile, infoLastBlockFile.ToString().c_str());
+            FlushBlockFile();
+            nLastBlockFile++;
+            infoLastBlockFile.SetNull();
+            pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile); // check whether data for the new file somehow already exist; can fail just fine
+            fUpdatedLast = true;
+        }
+        pos.nFile = nLastBlockFile;
+        pos.nPos = infoLastBlockFile.nSize;
     }
 
-    pos.nFile = nLastBlockFile;
-    pos.nPos = infoLastBlockFile.nSize;
     infoLastBlockFile.nSize += nAddSize;
     infoLastBlockFile.AddBlock(nHeight, nTime);
 
-    unsigned int nOldChunks = (pos.nPos + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
-    unsigned int nNewChunks = (infoLastBlockFile.nSize + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
-    if (nNewChunks > nOldChunks) {
-        FILE *file = OpenBlockFile(pos);
-        if (file) {
-            printf("Pre-allocating up to position 0x%x in blk%05u.dat\n", nNewChunks * BLOCKFILE_CHUNK_SIZE, pos.nFile);
-            AllocateFileRange(file, pos.nPos, nNewChunks * BLOCKFILE_CHUNK_SIZE - pos.nPos);
+    if (!fKnown) {
+        unsigned int nOldChunks = (pos.nPos + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
+        unsigned int nNewChunks = (infoLastBlockFile.nSize + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
+        if (nNewChunks > nOldChunks) {
+            FILE *file = OpenBlockFile(pos);
+            if (file) {
+                printf("Pre-allocating up to position 0x%x in blk%05u.dat\n", nNewChunks * BLOCKFILE_CHUNK_SIZE, pos.nFile);
+                AllocateFileRange(file, pos.nPos, nNewChunks * BLOCKFILE_CHUNK_SIZE - pos.nPos);
+            }
+            fclose(file);
         }
-        fclose(file);
     }
 
     if (!pblocktree->WriteBlockFileInfo(nLastBlockFile, infoLastBlockFile))
@@ -1996,7 +2007,7 @@ bool CBlock::CheckBlock(bool fCheckPOW, bool fCheckMerkleRoot) const
     return true;
 }
 
-bool CBlock::AcceptBlock()
+bool CBlock::AcceptBlock(CDiskBlockPos *dbp)
 {
     // Check for duplicate
     uint256 hash = GetHash();
@@ -2004,11 +2015,15 @@ bool CBlock::AcceptBlock()
         return error("AcceptBlock() : block already in mapBlockIndex");
 
     // Get prev block index
+    CBlockIndex* pindexPrev = NULL;
+    int nHeight = 0;
+    if (hash != hashGenesisBlock) {
+
     map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hashPrevBlock);
     if (mi == mapBlockIndex.end())
         return DoS(10, error("AcceptBlock() : prev block not found"));
-    CBlockIndex* pindexPrev = (*mi).second;
-    int nHeight = pindexPrev->nHeight+1;
+    pindexPrev = (*mi).second;
+    nHeight = pindexPrev->nHeight+1;
 
     // Check proof of work
     if (nBits != GetNextWorkRequired(pindexPrev, this))
@@ -2048,16 +2063,22 @@ bool CBlock::AcceptBlock()
                 return DoS(100, error("AcceptBlock() : block height mismatch in coinbase"));
         }
     }
+    }
 
     // Write block to history file
     unsigned int nBlockSize = ::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION);
-    if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION)))
-        return error("AcceptBlock() : out of disk space");
     CDiskBlockPos blockPos;
-    if (!FindBlockPos(blockPos, nBlockSize+8, nHeight, nTime))
+    if (dbp == NULL) {
+        if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION)))
+            return error("AcceptBlock() : out of disk space");
+    } else {
+        blockPos = *dbp;
+    }
+    if (!FindBlockPos(blockPos, nBlockSize+8, nHeight, nTime, dbp != NULL))
         return error("AcceptBlock() : FindBlockPos failed");
-    if (!WriteToDisk(blockPos))
-        return error("AcceptBlock() : WriteToDisk failed");
+    if (dbp == NULL)
+        if (!WriteToDisk(blockPos))
+            return error("AcceptBlock() : WriteToDisk failed");
     if (!AddToBlockIndex(blockPos))
         return error("AcceptBlock() : AddToBlockIndex failed");
 
@@ -2086,7 +2107,7 @@ bool CBlockIndex::IsSuperMajority(int minVersion, const CBlockIndex* pstart, uns
     return (nFound >= nRequired);
 }
 
-bool ProcessBlock(CNode* pfrom, CBlock* pblock)
+bool ProcessBlock(CNode* pfrom, CBlock* pblock, CDiskBlockPos *dbp)
 {
     // Check for duplicate
     uint256 hash = pblock->GetHash();
@@ -2124,7 +2145,7 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
 
 
     // If we don't already have its previous block, shunt it off to holding area until we get it
-    if (!mapBlockIndex.count(pblock->hashPrevBlock))
+    if (pblock->hashPrevBlock != 0 && !mapBlockIndex.count(pblock->hashPrevBlock))
     {
         printf("ProcessBlock: ORPHAN BLOCK, prev=%s\n", pblock->hashPrevBlock.ToString().substr(0,20).c_str());
 
@@ -2141,7 +2162,7 @@ bool ProcessBlock(CNode* pfrom, CBlock* pblock)
     }
 
     // Store to disk
-    if (!pblock->AcceptBlock())
+    if (!pblock->AcceptBlock(dbp))
         return error("ProcessBlock() : AcceptBlock FAILED");
 
     // Recursively process any orphan blocks that depended on this one
@@ -2304,6 +2325,11 @@ bool static LoadBlockIndexDB()
     // Load bnBestInvalidWork, OK if it doesn't exist
     pblocktree->ReadBestInvalidWork(bnBestInvalidWork);
 
+    // Check whether we need to continue reindexing
+    bool fReindexing = false;
+    pblocktree->ReadReindexing(fReindexing);
+    fReindex |= fReindexing;
+
     // Verify blocks in the best chain
     int nCheckLevel = GetArg("-checklevel", 1);
     int nCheckDepth = GetArg( "-checkblocks", 2500);
@@ -2337,7 +2363,7 @@ bool static LoadBlockIndexDB()
     return true;
 }
 
-bool LoadBlockIndex(bool fAllowNew)
+bool LoadBlockIndex()
 {
     if (fTestNet)
     {
@@ -2348,6 +2374,9 @@ bool LoadBlockIndex(bool fAllowNew)
         hashGenesisBlock = uint256("000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943");
     }
 
+    if (fReindex)
+        return true;
+
     //
     // Load block index from databases
     //
@@ -2359,9 +2388,6 @@ bool LoadBlockIndex(bool fAllowNew)
     //
     if (mapBlockIndex.empty())
     {
-        if (!fAllowNew)
-            return false;
-
         // Genesis Block:
         // CBlock(hash=000000000019d6, ver=1, hashPrevBlock=00000000000000, hashMerkleRoot=4a5e1e, nTime=1231006505, nBits=1d00ffff, nNonce=2083236893, vtx=1)
         //   CTransaction(hash=4a5e1e, ver=1, vin.size=1, vout.size=1, nLockTime=0)
@@ -2487,110 +2513,71 @@ void PrintBlockTree()
     }
 }
 
-bool LoadExternalBlockFile(FILE* fileIn)
+bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp)
 {
     int64 nStart = GetTimeMillis();
 
     int nLoaded = 0;
     {
-        try {
-            CAutoFile blkdat(fileIn, SER_DISK, CLIENT_VERSION);
-            unsigned int nPos = 0;
-            while (nPos != (unsigned int)-1 && blkdat.good() && !fRequestShutdown)
-            {
-                unsigned char pchData[65536];
-                do {
-                    fseek(blkdat, nPos, SEEK_SET);
-                    int nRead = fread(pchData, 1, sizeof(pchData), blkdat);
-                    if (nRead <= 8)
-                    {
-                        nPos = (unsigned int)-1;
-                        break;
-                    }
-                    void* nFind = memchr(pchData, pchMessageStart[0], nRead+1-sizeof(pchMessageStart));
-                    if (nFind)
-                    {
-                        if (memcmp(nFind, pchMessageStart, sizeof(pchMessageStart))==0)
-                        {
-                            nPos += ((unsigned char*)nFind - pchData) + sizeof(pchMessageStart);
-                            break;
-                        }
-                        nPos += ((unsigned char*)nFind - pchData) + 1;
-                    }
-                    else
-                        nPos += sizeof(pchData) - sizeof(pchMessageStart) + 1;
-                } while(!fRequestShutdown);
-                if (nPos == (unsigned int)-1)
-                    break;
-                fseek(blkdat, nPos, SEEK_SET);
-                unsigned int nSize;
+        CBufferedFile blkdat(fileIn, 2*MAX_BLOCK_SIZE, MAX_BLOCK_SIZE+8, SER_DISK, CLIENT_VERSION);
+        uint64 nStartByte = 0;
+        if (dbp) {
+            // (try to) skip already indexed part
+            CBlockFileInfo info;
+            if (pblocktree->ReadBlockFileInfo(dbp->nFile, info)) {
+                nStartByte = info.nSize;
+                blkdat.Seek(info.nSize);
+            }
+        }
+        uint64 nRewind = blkdat.GetPos();
+        while (blkdat.good() && !blkdat.eof() && !fShutdown) {
+            blkdat.SetPos(nRewind);
+            nRewind++; // start one byte further next time, in case of failure
+            blkdat.SetLimit(); // remove former limit
+            unsigned int nSize = 0;
+            try {
+                // locate a header
+                unsigned char buf[4];
+                blkdat.FindByte(pchMessageStart[0]);
+                nRewind = blkdat.GetPos()+1;
+                blkdat >> FLATDATA(buf);
+                if (memcmp(buf, pchMessageStart, 4))
+                    continue;
+                // read size
                 blkdat >> nSize;
-                if (nSize > 0 && nSize <= MAX_BLOCK_SIZE)
-                {
-                    CBlock block;
-                    blkdat >> block;
+                if (nSize < 80 || nSize > MAX_BLOCK_SIZE)
+                    continue;
+            } catch (std::exception &e) {
+                // no valid block header found; don't complain
+                break;
+            }
+            try {
+                // read block
+                uint64 nBlockPos = blkdat.GetPos();
+                blkdat.SetLimit(nBlockPos + nSize);
+                CBlock block;
+                blkdat >> block;
+                nRewind = blkdat.GetPos();
+
+                // process block
+                if (nBlockPos >= nStartByte) {
                     LOCK(cs_main);
-                    if (ProcessBlock(NULL,&block))
-                    {
+                    if (dbp)
+                        dbp->nPos = nBlockPos;
+                    if (ProcessBlock(NULL, &block, dbp))
                         nLoaded++;
-                        nPos += 4 + nSize;
-                    }
                 }
+            } catch (std::exception &e) {
+                printf("%s() : Deserialize or I/O error caught during load\n", __PRETTY_FUNCTION__);
             }
         }
-        catch (std::exception &e) {
-            printf("%s() : Deserialize or I/O error caught during load\n",
-                   __PRETTY_FUNCTION__);
-        }
+        fclose(fileIn);
     }
-    printf("Loaded %i blocks from external file in %"PRI64d"ms\n", nLoaded, GetTimeMillis() - nStart);
+    if (nLoaded > 0)
+        printf("Loaded %i blocks from external file in %"PRI64d"ms\n", nLoaded, GetTimeMillis() - nStart);
     return nLoaded > 0;
 }
 
-struct CImportingNow
-{
-    CImportingNow() {
-        assert(fImporting == false);
-        fImporting = true;
-    }
-
-    ~CImportingNow() {
-        assert(fImporting == true);
-        fImporting = false;
-    }
-};
-
-void ThreadImport(void *data) {
-    std::vector<boost::filesystem::path> *vFiles = reinterpret_cast<std::vector<boost::filesystem::path>*>(data);
-
-    RenameThread("bitcoin-loadblk");
-
-    CImportingNow imp;
-    vnThreadsRunning[THREAD_IMPORT]++;
-
-    // -loadblock=
-    BOOST_FOREACH(boost::filesystem::path &path, *vFiles) {
-        FILE *file = fopen(path.string().c_str(), "rb");
-        if (file)
-            LoadExternalBlockFile(file);
-    }
-
-    // hardcoded $DATADIR/bootstrap.dat
-    filesystem::path pathBootstrap = GetDataDir() / "bootstrap.dat";
-    if (filesystem::exists(pathBootstrap)) {
-        FILE *file = fopen(pathBootstrap.string().c_str(), "rb");
-        if (file) {
-            filesystem::path pathBootstrapOld = GetDataDir() / "bootstrap.dat.old";
-            LoadExternalBlockFile(file);
-            RenameOver(pathBootstrap, pathBootstrapOld);
-        }
-    }
-
-    delete vFiles;
-
-    vnThreadsRunning[THREAD_IMPORT]--;
-}
-
 
 
 
@@ -2800,7 +2787,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
 
         // Ask the first connected node for block updates
         static int nAskedForBlocks = 0;
-        if (!pfrom->fClient && !pfrom->fOneShot && !fImporting &&
+        if (!pfrom->fClient && !pfrom->fOneShot && !fImporting && !fReindex &&
             (pfrom->nStartingHeight > (nBestHeight - 144)) &&
             (pfrom->nVersion < NOBLKS_VERSION_START ||
              pfrom->nVersion >= NOBLKS_VERSION_END) &&
@@ -2937,7 +2924,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
                 printf("  got inventory: %s  %s\n", inv.ToString().c_str(), fAlreadyHave ? "have" : "new");
 
             if (!fAlreadyHave) {
-                if (!fImporting)
+                if (!fImporting && !fReindex)
                     pfrom->AskFor(inv);
             } else if (inv.type == MSG_BLOCK && mapOrphanBlocks.count(inv.hash)) {
                 pfrom->PushGetBlocks(pindexBest, GetOrphanRoot(mapOrphanBlocks[inv.hash]));
@@ -3167,7 +3154,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
     }
 
 
-    else if (strCommand == "block")
+    else if (strCommand == "block" && !fImporting && !fReindex) // Ignore blocks received while importing
     {
         CBlock block;
         vRecv >> block;
diff --git a/src/main.h b/src/main.h
index 899cabd85a..25dddae0f8 100644
--- a/src/main.h
+++ b/src/main.h
@@ -88,6 +88,7 @@ extern CCriticalSection cs_setpwalletRegistered;
 extern std::set<CWallet*> setpwalletRegistered;
 extern unsigned char pchMessageStart[4];
 extern bool fImporting;
+extern bool fReindex;
 extern unsigned int nCoinCacheSize;
 
 // Settings
@@ -109,11 +110,12 @@ class CCoinsViewCache;
 void RegisterWallet(CWallet* pwalletIn);
 void UnregisterWallet(CWallet* pwalletIn);
 void SyncWithWallets(const uint256 &hash, const CTransaction& tx, const CBlock* pblock = NULL, bool fUpdate = false);
-bool ProcessBlock(CNode* pfrom, CBlock* pblock);
+bool ProcessBlock(CNode* pfrom, CBlock* pblock, CDiskBlockPos *dbp = NULL);
 bool CheckDiskSpace(uint64 nAdditionalBytes=0);
 FILE* OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly = false);
 FILE* OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly = false);
-bool LoadBlockIndex(bool fAllowNew=true);
+bool LoadExternalBlockFile(FILE* fileIn, CDiskBlockPos *dbp = NULL);
+bool LoadBlockIndex();
 void PrintBlockTree();
 CBlockIndex* FindBlockByHeight(int nHeight);
 bool ProcessMessages(CNode* pfrom);
@@ -1261,7 +1263,8 @@ public:
     bool CheckBlock(bool fCheckPOW=true, bool fCheckMerkleRoot=true) const;
 
     // Store block on disk
-    bool AcceptBlock();
+    // if dbp is provided, the file is known to already reside on disk
+    bool AcceptBlock(CDiskBlockPos *dbp = NULL);
 };
 
 
diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 988f4185b9..9c47daf85d 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -489,7 +489,8 @@ void BitcoinGUI::setNumBlocks(int count, int nTotalBlocks)
     statusBar()->clearMessage();
 
     // don't show / hide progress bar and its label if we have no connection to the network
-    if (!clientModel || (clientModel->getNumConnections() == 0 && !clientModel->isImporting()))
+    enum BlockSource blockSource = clientModel ? clientModel->getBlockSource() : BLOCK_SOURCE_NONE;
+    if (blockSource == BLOCK_SOURCE_NONE || (blockSource == BLOCK_SOURCE_NETWORK && clientModel->getNumConnections() == 0))
     {
         progressBarLabel->setVisible(false);
         progressBar->setVisible(false);
@@ -499,26 +500,37 @@ void BitcoinGUI::setNumBlocks(int count, int nTotalBlocks)
 
     QString tooltip;
 
+    QString importText;
+    switch (blockSource) {
+    case BLOCK_SOURCE_NONE:
+    case BLOCK_SOURCE_NETWORK:
+        importText = tr("Synchronizing with network...");
+    case BLOCK_SOURCE_DISK:
+        importText = tr("Importing blocks from disk...");
+    case BLOCK_SOURCE_REINDEX:
+        importText = tr("Reindexing blocks on disk...");
+    }
+
     if(count < nTotalBlocks)
     {
         int nRemainingBlocks = nTotalBlocks - count;
         float nPercentageDone = count / (nTotalBlocks * 0.01f);
 
-        progressBarLabel->setText(tr(clientModel->isImporting() ? "Importing blocks..." : "Synchronizing with network..."));
+        progressBarLabel->setText(importText);
         progressBarLabel->setVisible(true);
         progressBar->setFormat(tr("~%n block(s) remaining", "", nRemainingBlocks));
         progressBar->setMaximum(nTotalBlocks);
         progressBar->setValue(count);
         progressBar->setVisible(true);
 
-        tooltip = tr("Downloaded %1 of %2 blocks of transaction history (%3% done).").arg(count).arg(nTotalBlocks).arg(nPercentageDone, 0, 'f', 2);
+        tooltip = tr("Processed %1 of %2 blocks of transaction history (%3% done).").arg(count).arg(nTotalBlocks).arg(nPercentageDone, 0, 'f', 2);
     }
     else
     {
         progressBarLabel->setVisible(false);
 
         progressBar->setVisible(false);
-        tooltip = tr("Downloaded %1 blocks of transaction history.").arg(count);
+        tooltip = tr("Processed %1 blocks of transaction history.").arg(count);
     }
 
     QDateTime lastBlockDate = clientModel->getLastBlockDate();
diff --git a/src/qt/clientmodel.cpp b/src/qt/clientmodel.cpp
index 25db695a0b..9b7362d757 100644
--- a/src/qt/clientmodel.cpp
+++ b/src/qt/clientmodel.cpp
@@ -101,9 +101,13 @@ bool ClientModel::inInitialBlockDownload() const
     return IsInitialBlockDownload();
 }
 
-bool ClientModel::isImporting() const
+enum BlockSource ClientModel::getBlockSource() const
 {
-    return fImporting;
+    if (fReindex)
+        return BLOCK_SOURCE_REINDEX;
+    if (fImporting)
+        return BLOCK_SOURCE_DISK;
+    return BLOCK_SOURCE_NETWORK;
 }
 
 int ClientModel::getNumBlocksOfPeers() const
diff --git a/src/qt/clientmodel.h b/src/qt/clientmodel.h
index fd0135b3e6..7d6401ab25 100644
--- a/src/qt/clientmodel.h
+++ b/src/qt/clientmodel.h
@@ -13,6 +13,13 @@ class QDateTime;
 class QTimer;
 QT_END_NAMESPACE
 
+enum BlockSource {
+    BLOCK_SOURCE_NONE,
+    BLOCK_SOURCE_NETWORK,
+    BLOCK_SOURCE_DISK,
+    BLOCK_SOURCE_REINDEX
+};
+
 /** Model for Bitcoin network client. */
 class ClientModel : public QObject
 {
@@ -34,7 +41,7 @@ public:
     //! Return true if core is doing initial block download
     bool inInitialBlockDownload() const;
     //! Return true if core is importing blocks
-    bool isImporting() const;
+    enum BlockSource getBlockSource() const;
     //! Return conservative estimate of total number of blocks, or 0 if unknown
     int getNumBlocksOfPeers() const;
     //! Return warnings to be displayed in status bar
diff --git a/src/serialize.h b/src/serialize.h
index 549e46cbc3..9e14666fac 100644
--- a/src/serialize.h
+++ b/src/serialize.h
@@ -1225,4 +1225,148 @@ public:
     }
 };
 
+/** Wrapper around a FILE* that implements a ring buffer to
+ *  deserialize from. It guarantees the ability to rewind
+ *  a given number of bytes. */
+class CBufferedFile
+{
+private:
+    FILE *src;          // source file
+    uint64 nSrcPos;     // how many bytes have been read from source
+    uint64 nReadPos;    // how many bytes have been read from this
+    uint64 nReadLimit;  // up to which position we're allowed to read
+    uint64 nRewind;     // how many bytes we guarantee to rewind
+    std::vector<char> vchBuf; // the buffer
+
+    short state;
+    short exceptmask;
+
+protected:
+    void setstate(short bits, const char *psz) {
+        state |= bits;
+        if (state & exceptmask)
+            throw std::ios_base::failure(psz);
+    }
+
+    // read data from the source to fill the buffer
+    bool Fill() {
+        unsigned int pos = nSrcPos % vchBuf.size();
+        unsigned int readNow = vchBuf.size() - pos;
+        unsigned int nAvail = vchBuf.size() - (nSrcPos - nReadPos) - nRewind;
+        if (nAvail < readNow)
+            readNow = nAvail;
+        if (readNow == 0)
+            return false;
+        size_t read = fread((void*)&vchBuf[pos], 1, readNow, src);
+        if (read == 0) {
+            setstate(std::ios_base::failbit, feof(src) ? "CBufferedFile::Fill : end of file" : "CBufferedFile::Fill : fread failed");
+            return false;
+        } else {
+            nSrcPos += read;
+            return true;
+        }
+    }
+
+public:
+    int nType;
+    int nVersion;
+
+    CBufferedFile(FILE *fileIn, uint64 nBufSize, uint64 nRewindIn, int nTypeIn, int nVersionIn) :
+        src(fileIn), nSrcPos(0), nReadPos(0), nReadLimit((uint64)(-1)), nRewind(nRewindIn), vchBuf(nBufSize, 0),
+        state(0), exceptmask(std::ios_base::badbit | std::ios_base::failbit), nType(nTypeIn), nVersion(nVersionIn) {
+    }
+
+    // check whether no error occurred
+    bool good() const {
+        return state == 0;
+    }
+
+    // check whether we're at the end of the source file
+    bool eof() const {
+        return nReadPos == nSrcPos && feof(src);
+    }
+
+    // read a number of bytes
+    CBufferedFile& read(char *pch, size_t nSize) {
+        if (nSize + nReadPos > nReadLimit)
+            throw std::ios_base::failure("Read attempted past buffer limit");
+        if (nSize + nRewind > vchBuf.size())
+            throw std::ios_base::failure("Read larger than buffer size");
+        while (nSize > 0) {
+            if (nReadPos == nSrcPos)
+                Fill();
+            unsigned int pos = nReadPos % vchBuf.size();
+            size_t nNow = nSize;
+            if (nNow + pos > vchBuf.size())
+                nNow = vchBuf.size() - pos;
+            if (nNow + nReadPos > nSrcPos)
+                nNow = nSrcPos - nReadPos;
+            memcpy(pch, &vchBuf[pos], nNow);
+            nReadPos += nNow;
+            pch += nNow;
+            nSize -= nNow;
+        }
+        return (*this);
+    }
+
+    // return the current reading position
+    uint64 GetPos() {
+        return nReadPos;
+    }
+
+    // rewind to a given reading position
+    bool SetPos(uint64 nPos) {
+        nReadPos = nPos;
+        if (nReadPos + nRewind < nSrcPos) {
+            nReadPos = nSrcPos - nRewind;
+            return false;
+        } else if (nReadPos > nSrcPos) {
+            nReadPos = nSrcPos;
+            return false;
+        } else {
+            return true;
+        }
+    }
+
+    bool Seek(uint64 nPos) {
+        long nLongPos = nPos;
+        if (nPos != (uint64)nLongPos)
+            return false;
+        if (fseek(src, nLongPos, SEEK_SET))
+            return false;
+        nLongPos = ftell(src);
+        nSrcPos = nLongPos;
+        nReadPos = nLongPos;
+        state = 0;
+        return true;
+    }
+
+    // prevent reading beyond a certain position
+    // no argument removes the limit
+    bool SetLimit(uint64 nPos = (uint64)(-1)) {
+        if (nPos < nReadPos)
+            return false;
+        nReadLimit = nPos;
+        return true;
+    }
+
+    template<typename T>
+    CBufferedFile& operator>>(T& obj) {
+        // Unserialize from this stream
+        ::Unserialize(*this, obj, nType, nVersion);
+        return (*this);
+    }
+
+    // search for a given byte in the stream, and remain positioned on it
+    void FindByte(char ch) {
+        while (true) {
+            if (nReadPos == nSrcPos)
+                Fill();
+            if (vchBuf[nReadPos % vchBuf.size()] == ch)
+                break;
+            nReadPos++;
+        }
+    }
+};
+
 #endif
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
index c1f47f786b..c8a565af3a 100644
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -22,7 +22,7 @@ struct TestingSetup {
         pblocktree = new CBlockTreeDB(true);
         pcoinsdbview = new CCoinsViewDB(true);
         pcoinsTip = new CCoinsViewCache(*pcoinsdbview);
-        LoadBlockIndex(true);
+        LoadBlockIndex();
         bool fFirstRun;
         pwalletMain = new CWallet("wallet.dat");
         pwalletMain->LoadWallet(fFirstRun);
diff --git a/src/txdb.cpp b/src/txdb.cpp
index d9972d5b06..93c5f23d8b 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -19,7 +19,7 @@ void static BatchWriteHashBestChain(CLevelDBBatch &batch, const uint256 &hash) {
     batch.Write('B', hash);
 }
 
-CCoinsViewDB::CCoinsViewDB(size_t nCacheSize, bool fMemory) : db(GetDataDir() / "coins", nCacheSize, fMemory) {
+CCoinsViewDB::CCoinsViewDB(size_t nCacheSize, bool fMemory, bool fWipe) : db(GetDataDir() / "coins", nCacheSize, fMemory, fWipe) {
 }
 
 bool CCoinsViewDB::GetCoins(uint256 txid, CCoins &coins) { 
@@ -64,7 +64,7 @@ bool CCoinsViewDB::BatchWrite(const std::map<uint256, CCoins> &mapCoins, CBlockI
     return db.WriteBatch(batch);
 }
 
-CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory) : CLevelDB(GetDataDir() / "blktree", nCacheSize, fMemory) {
+CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory, bool fWipe) : CLevelDB(GetDataDir() / "blktree", nCacheSize, fMemory, fWipe) {
 }
 
 bool CBlockTreeDB::WriteBlockIndex(const CDiskBlockIndex& blockindex)
@@ -94,6 +94,18 @@ bool CBlockTreeDB::WriteLastBlockFile(int nFile) {
     return Write('l', nFile);
 }
 
+bool CBlockTreeDB::WriteReindexing(bool fReindexing) {
+    if (fReindexing)
+        return Write('R', '1');
+    else
+        return Erase('R');
+}
+
+bool CBlockTreeDB::ReadReindexing(bool &fReindexing) {
+    fReindexing = Exists('R');
+    return true;
+}
+
 bool CBlockTreeDB::ReadLastBlockFile(int &nFile) {
     return Read('l', nFile);
 }
diff --git a/src/txdb.h b/src/txdb.h
index e13925c964..d7d327069f 100644
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -14,7 +14,7 @@ class CCoinsViewDB : public CCoinsView
 protected:
     CLevelDB db;
 public:
-    CCoinsViewDB(size_t nCacheSize, bool fMemory = false);
+    CCoinsViewDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false);
 
     bool GetCoins(uint256 txid, CCoins &coins);
     bool SetCoins(uint256 txid, const CCoins &coins);
@@ -29,7 +29,7 @@ public:
 class CBlockTreeDB : public CLevelDB
 {
 public:
-    CBlockTreeDB(size_t nCacheSize, bool fMemory = false);
+    CBlockTreeDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false);
 private:
     CBlockTreeDB(const CBlockTreeDB&);
     void operator=(const CBlockTreeDB&);
@@ -41,6 +41,8 @@ public:
     bool WriteBlockFileInfo(int nFile, const CBlockFileInfo &fileinfo);
     bool ReadLastBlockFile(int &nFile);
     bool WriteLastBlockFile(int nFile);
+    bool WriteReindexing(bool fReindex);
+    bool ReadReindexing(bool &fReindex);
     bool LoadBlockIndexGuts();
 };