Prevent crashes due to missing or corrupted database records

Any problems seen during deserialization will throw an uncaught
exception, crashing the entire bitcoin process.  Properly return an
error instead, so that we may at least log the error and gracefully
shutdown other portions of the app.

src/db.cpp

@@ -416,9 +416,15 @@ bool CTxDB::ReadOwnerTxes(uint160 hash160, int nMinHeight, vector<CTransaction>&
         string strType;
         uint160 hashItem;
         CDiskTxPos pos;
-        ssKey >> strType >> hashItem >> pos;
         int nItemHeight;
+
+        try {
+            ssKey >> strType >> hashItem >> pos;
             ssValue >> nItemHeight;
+        }
+        catch (std::exception &e) {
+            return error("%s() : deserialize error", __PRETTY_FUNCTION__);
+        }
 
         // Read transaction
         if (strType != "owner" || hashItem != hash160)
@@ -533,6 +539,8 @@ bool CTxDB::LoadBlockIndex()
             return false;
 
         // Unserialize
+
+        try {
         string strType;
         ssKey >> strType;
         if (strType == "blockindex" && !fRequestShutdown)
@@ -564,6 +572,10 @@ bool CTxDB::LoadBlockIndex()
         {
             break; // if shutdown requested or finished loading block index
         }
+        }    // try
+        catch (std::exception &e) {
+            return error("%s() : deserialize error", __PRETTY_FUNCTION__);
+        }
     }
     pcursor->close();
 

src/db.h

@@ -72,8 +72,13 @@ protected:
             return false;
 
         // Unserialize value
+        try {
             CDataStream ssValue((char*)datValue.get_data(), (char*)datValue.get_data() + datValue.get_size(), SER_DISK, CLIENT_VERSION);
             ssValue >> value;
+        }
+        catch (std::exception &e) {
+            return false;
+        }
 
         // Clear and free memory
         memset(datValue.get_data(), 0, datValue.get_size());