Add -zapwallettxes cli/config option, used for wallet recovery

This diagnostic tool removes all "tx" records from the wallet db,
then forces a full rescan, to rebuild "tx" records accurately.

src/init.cpp

@@ -305,6 +305,7 @@ std::string HelpMessage()
         "  -upgradewallet         " + _("Upgrade wallet to latest format") + "\n" +
         "  -keypool=<n>           " + _("Set key pool size to <n> (default: 100)") + "\n" +
         "  -rescan                " + _("Rescan the block chain for missing wallet transactions") + "\n" +
+        "  -zapwallettxes         " + _("Clear list of wallet transactions (diagnostic tool; implies -rescan)") + "\n" +
         "  -salvagewallet         " + _("Attempt to recover private keys from a corrupt wallet.dat") + "\n" +
         "  -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" +
@@ -437,6 +438,12 @@ bool AppInit2()
         SoftSetBoolArg("-rescan", true);
     }
 
+    if (GetBoolArg("-zapwallettxes", false)) {
+        // -zapwallettx implies a rescan
+        if (SoftSetBoolArg("-rescan", true))
+            printf("AppInit2 : parameter interaction: -zapwallettxes=1 -> setting -rescan=1\n");
+    }
+
     // ********************************************************* Step 3: parameter-to-internal-flags
 
     // -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
@@ -839,6 +846,19 @@ bool AppInit2()
 
     // ********************************************************* Step 8: load wallet
 
+    if (GetBoolArg("-zapwallettxes", false)) {
+        uiInterface.InitMessage(_("Zapping all transactions from wallet..."));
+
+        pwalletMain = new CWallet(strWalletFileName);
+        DBErrors nZapWalletRet = pwalletMain->ZapWalletTx();
+        if (nZapWalletRet != DB_LOAD_OK) {
+            uiInterface.InitMessage(_("Error loading wallet.dat: Wallet corrupted"));
+            return false;
+        }
+        delete pwalletMain;
+        pwalletMain = NULL;
+    }
+
     uiInterface.InitMessage(_("Loading wallet..."));
     printf("Loading wallet...\n");
     nStart = GetTimeMillis();

src/wallet.cpp

@@ -2243,6 +2243,28 @@ DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
     return DB_LOAD_OK;
 }
 
+DBErrors CWallet::ZapWalletTx()
+{
+    if (!fFileBacked)
+        return DB_LOAD_OK;
+    DBErrors nZapWalletTxRet = CWalletDB(strWalletFile,"cr+").ZapWalletTx(this);
+    if (nZapWalletTxRet == DB_NEED_REWRITE)
+    {
+        if (CDB::Rewrite(strWalletFile, "\x04pool"))
+        {
+            LOCK(cs_wallet);
+            setKeyPool.clear();
+            // Note: can't top-up keypool here, because wallet is locked.
+            // User will be prompted to unlock wallet the next operation
+            // the requires a new key.
+        }
+    }
+
+    if (nZapWalletTxRet != DB_LOAD_OK)
+        return nZapWalletTxRet;
+
+    return DB_LOAD_OK;
+}
 
 bool CWallet::SetAddressBookName(const CTxDestination& address, const string& strName)
 {

src/wallet.h

@@ -311,6 +311,8 @@ class CWallet : public CCryptoKeyStore
 
     DBErrors LoadWallet(bool& fFirstRunRet);
 
+    DBErrors ZapWalletTx();
+
     bool SetAddressBookName(const CTxDestination& address, const std::string& strName);
 
     bool DelAddressBookName(const CTxDestination& address);

src/walletdb.cpp

@@ -554,6 +554,86 @@ DBErrors CWalletDB::LoadWallet(CWallet* pwallet)
     return result;
 }
 
+DBErrors CWalletDB::FindWalletTx(CWallet* pwallet, vector<uint256>& vTxHash)
+{
+    pwallet->vchDefaultKey = CPubKey();
+    CWalletScanState wss;
+    bool fNoncriticalErrors = false;
+    DBErrors result = DB_LOAD_OK;
+
+    try {
+        LOCK(pwallet->cs_wallet);
+        int nMinVersion = 0;
+        if (Read((string)"minversion", nMinVersion))
+        {
+            if (nMinVersion > CLIENT_VERSION)
+                return DB_TOO_NEW;
+            pwallet->LoadMinVersion(nMinVersion);
+        }
+
+        // Get cursor
+        Dbc* pcursor = GetCursor();
+        if (!pcursor)
+        {
+            printf("Error getting wallet database cursor\n");
+            return DB_CORRUPT;
+        }
+
+        while (true)
+        {
+            // Read next record
+            CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+            CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+            int ret = ReadAtCursor(pcursor, ssKey, ssValue);
+            if (ret == DB_NOTFOUND)
+                break;
+            else if (ret != 0)
+            {
+                printf("Error reading next record from wallet database\n");
+                return DB_CORRUPT;
+            }
+
+            string strType;
+            ssKey >> strType;
+            if (strType == "tx") {
+                uint256 hash;
+                ssKey >> hash;
+
+                vTxHash.push_back(hash);
+            }
+        }
+        pcursor->close();
+    }
+    catch (boost::thread_interrupted) {
+        throw;
+    }
+    catch (...) {
+        result = DB_CORRUPT;
+    }
+
+    if (fNoncriticalErrors && result == DB_LOAD_OK)
+        result = DB_NONCRITICAL_ERROR;
+
+    return result;
+}
+
+DBErrors CWalletDB::ZapWalletTx(CWallet* pwallet)
+{
+    // build list of wallet TXs
+    vector<uint256> vTxHash;
+    DBErrors err = FindWalletTx(pwallet, vTxHash);
+    if (err != DB_LOAD_OK)
+        return err;
+
+    // erase each wallet TX
+    BOOST_FOREACH (uint256& hash, vTxHash) {
+        if (!EraseTx(hash))
+            return DB_CORRUPT;
+    }
+
+    return DB_LOAD_OK;
+}
+
 void ThreadFlushWalletDB(void* parg)
 {
     // Make this thread recognisable as the wallet flushing thread

src/walletdb.h

@@ -204,6 +204,9 @@ class CWalletDB : public CDB
 
     DBErrors ReorderTransactions(CWallet*);
     DBErrors LoadWallet(CWallet* pwallet);
+    DBErrors FindWalletTx(CWallet* pwallet, std::vector<uint256>& vTxHash);
+    DBErrors ZapWalletTx(CWallet* pwallet);
+
     static bool Recover(CDBEnv& dbenv, std::string filename, bool fOnlyKeys);
     static bool Recover(CDBEnv& dbenv, std::string filename);
 };