Handle corrupt wallets gracefully.

Corrupt wallets used to cause a DB_RUNRECOVERY uncaught exception and a
crash. This commit does three things:

1) Runs a BDB verify early in the startup process, and if there is a
low-level problem with the database:
  + Moves the bad wallet.dat to wallet.timestamp.bak
  + Runs a 'salvage' operation to get key/value pairs, and
    writes them to a new wallet.dat
  + Continues with startup.

2) Much more tolerant of serialization errors. All errors in deserialization
are reported by tolerated EXCEPT for errors related to reading keypairs
or master key records-- those are reported and then shut down, so the user
can get help (or recover from a backup).

3) Adds a new -salvagewallet option, which:
 + Moves the wallet.dat to wallet.timestamp.bak
 + extracts ONLY keypairs and master keys into a new wallet.dat
 + soft-sets -rescan, to recreate transaction history

This was tested by randomly corrupting testnet wallets using a little
python script I wrote (https://gist.github.com/3812689)

1 files changed, 53 insertions, 18 deletions

diff --git a/src/init.cpp b/src/init.cpp
index d271893644..480d65422c 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -279,6 +279,7 @@ 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" +
+        "  -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" +
         "  -loadblock=<file>      " + _("Imports blocks from external blk000?.dat file") + "\n" +
@@ -379,6 +380,11 @@ bool AppInit2()
         SoftSetBoolArg("-discover", false);
     }
 
+    if (GetBoolArg("-salvagewallet")) {
+        // Rewrite just private keys: rescan to find transactions
+        SoftSetBoolArg("-rescan", true);
+    }
+
     // ********************************************************* Step 3: parameter-to-internal-flags
 
     fDebug = GetBoolArg("-debug");
@@ -434,12 +440,13 @@ bool AppInit2()
 
     // ********************************************************* Step 4: application initialization: dir lock, daemonize, pidfile, debug log
 
+    const char* pszDataDir = GetDataDir().string().c_str();
+
     // Make sure only a single Bitcoin process is using the data directory.
     boost::filesystem::path pathLockFile = GetDataDir() / ".lock";
     FILE* file = fopen(pathLockFile.string().c_str(), "a"); // empty lock file; created if it doesn't exist.
     if (file) fclose(file);
     static boost::interprocess::file_lock lock(pathLockFile.string().c_str());
-    const char* pszDataDir = GetDataDir().string().c_str();
     if (!lock.try_lock())
         return InitError(strprintf(_("Cannot obtain a lock on data directory %s.  Bitcoin is probably already running."), pszDataDir));
 
@@ -481,7 +488,38 @@ bool AppInit2()
 
     int64 nStart;
 
-    // ********************************************************* Step 5: network initialization
+    // ********************************************************* Step 5: verify database integrity
+
+    uiInterface.InitMessage(_("Verifying database integrity..."));
+
+    if (!bitdb.Open(GetDataDir()))
+    {
+        string msg = strprintf(_("Error initializing database environment %s!"
+                                 " To recover, BACKUP THAT DIRECTORY, then remove"
+                                 " everything from it except for wallet.dat."), pszDataDir);
+        return InitError(msg);
+    }
+
+    if (GetBoolArg("-salvagewallet"))
+    {
+        // Recover readable keypairs:
+        if (!CWalletDB::Recover(bitdb, "wallet.dat", true))
+            return false;
+    }
+
+    CDBEnv::VerifyResult r = bitdb.Verify("wallet.dat", CWalletDB::Recover);
+    if (r == CDBEnv::RECOVER_OK)
+    {
+        string msg = strprintf(_("Warning: wallet.dat corrupt, data salvaged!"
+                                 " Original wallet.dat saved as wallet.{timestamp}.bak in %s; if"
+                                 " your balance or transactions are incorrect you should"
+                                 " restore from a backup."), pszDataDir);
+        uiInterface.ThreadSafeMessageBox(msg, _("Bitcoin"), CClientUIInterface::OK | CClientUIInterface::ICON_EXCLAMATION | CClientUIInterface::MODAL);
+    }
+    if (r == CDBEnv::RECOVER_FAIL)
+        return InitError(_("wallet.dat corrupt, salvage failed"));
+
+    // ********************************************************* Step 6: network initialization
 
     int nSocksVersion = GetArg("-socks", 5);
 
@@ -587,15 +625,7 @@ bool AppInit2()
     BOOST_FOREACH(string strDest, mapMultiArgs["-seednode"])
         AddOneShot(strDest);
 
-    // ********************************************************* Step 6: load blockchain
-
-    if (!bitdb.Open(GetDataDir()))
-    {
-        string msg = strprintf(_("Error initializing database environment %s!"
-                                 " To recover, BACKUP THAT DIRECTORY, then remove"
-                                 " everything from it except for wallet.dat."), pszDataDir);
-        return InitError(msg);
-    }
+    // ********************************************************* Step 7: load blockchain
 
     if (GetBoolArg("-loadblockindextest"))
     {
@@ -650,18 +680,24 @@ bool AppInit2()
         return false;
     }
 
-    // ********************************************************* Step 7: load wallet
+    // ********************************************************* Step 8: load wallet
 
     uiInterface.InitMessage(_("Loading wallet..."));
     printf("Loading wallet...\n");
     nStart = GetTimeMillis();
     bool fFirstRun = true;
     pwalletMain = new CWallet("wallet.dat");
-    int nLoadWalletRet = pwalletMain->LoadWallet(fFirstRun);
+    DBErrors nLoadWalletRet = pwalletMain->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DB_LOAD_OK)
     {
         if (nLoadWalletRet == DB_CORRUPT)
             strErrors << _("Error loading wallet.dat: Wallet corrupted") << "\n";
+        else if (nLoadWalletRet == DB_NONCRITICAL_ERROR)
+        {
+            string msg(_("Warning: error reading wallet.dat! All keys read correctly, but transaction data"
+                         " or address book entries might be missing or incorrect."));
+            uiInterface.ThreadSafeMessageBox(msg, _("Bitcoin"), CClientUIInterface::OK | CClientUIInterface::ICON_EXCLAMATION | CClientUIInterface::MODAL);
+        }
         else if (nLoadWalletRet == DB_TOO_NEW)
             strErrors << _("Error loading wallet.dat: Wallet requires newer version of Bitcoin") << "\n";
         else if (nLoadWalletRet == DB_NEED_REWRITE)
@@ -727,7 +763,7 @@ bool AppInit2()
         printf(" rescan      %15"PRI64d"ms\n", GetTimeMillis() - nStart);
     }
 
-    // ********************************************************* Step 8: import blocks
+    // ********************************************************* Step 9: import blocks
 
     if (mapArgs.count("-loadblock"))
     {
@@ -753,7 +789,7 @@ bool AppInit2()
         }
     }
 
-    // ********************************************************* Step 9: load peers
+    // ********************************************************* Step 10: load peers
 
     uiInterface.InitMessage(_("Loading addresses..."));
     printf("Loading addresses...\n");
@@ -768,7 +804,7 @@ bool AppInit2()
     printf("Loaded %i addresses from peers.dat  %"PRI64d"ms\n",
            addrman.size(), GetTimeMillis() - nStart);
 
-    // ********************************************************* Step 10: start node
+    // ********************************************************* Step 11: start node
 
     if (!CheckDiskSpace())
         return false;
@@ -788,7 +824,7 @@ bool AppInit2()
     if (fServer)
         NewThread(ThreadRPCServer, NULL);
 
-    // ********************************************************* Step 11: finished
+    // ********************************************************* Step 12: finished
 
     uiInterface.InitMessage(_("Done loading"));
     printf("Done loading\n");
@@ -808,4 +844,3 @@ bool AppInit2()
 
     return true;
 }
-