Catch UTXO set read errors and shutdown

Github-Pull: #5619
Rebased-From: 13cdce4

src/init.cpp

@@ -112,7 +112,28 @@ bool ShutdownRequested()
     return fRequestShutdown;
 }
 
+class CCoinsViewErrorCatcher : public CCoinsViewBacked
+{
+public:
+    CCoinsViewErrorCatcher(CCoinsView* view) : CCoinsViewBacked(view) {}
+    bool GetCoins(const uint256 &txid, CCoins &coins) const {
+        try {
+            return CCoinsViewBacked::GetCoins(txid, coins);
+        } catch(const std::runtime_error& e) {
+            uiInterface.ThreadSafeMessageBox(_("Error reading from database, shutting down."), "", CClientUIInterface::MSG_ERROR);
+            LogPrintf("Error reading from database: %s\n", e.what());
+            // Starting the shutdown sequence and returning false to the caller would be
+            // interpreted as 'entry not found' (as opposed to unable to read data), and
+            // could lead to invalid interpration. Just exit immediately, as we can't
+            // continue anyway, and all writes should be atomic.
+            abort();
+        }
+    }
+    // Writes do not need similar protection, as failure to write is handled by the caller.
+};
+
 static CCoinsViewDB *pcoinsdbview = NULL;
+static CCoinsViewErrorCatcher *pcoinscatcher = NULL;
 
 void Shutdown()
 {
@@ -155,6 +176,8 @@ void Shutdown()
         }
         delete pcoinsTip;
         pcoinsTip = NULL;
+        delete pcoinscatcher;
+        pcoinscatcher = NULL;
         delete pcoinsdbview;
         pcoinsdbview = NULL;
         delete pblocktree;
@@ -986,11 +1009,13 @@ bool AppInit2(boost::thread_group& threadGroup)
                 UnloadBlockIndex();
                 delete pcoinsTip;
                 delete pcoinsdbview;
+                delete pcoinscatcher;
                 delete pblocktree;
 
                 pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReindex);
                 pcoinsdbview = new CCoinsViewDB(nCoinDBCache, false, fReindex);
-                pcoinsTip = new CCoinsViewCache(pcoinsdbview);
+                pcoinscatcher = new CCoinsViewErrorCatcher(pcoinsdbview);
+                pcoinsTip = new CCoinsViewCache(pcoinscatcher);
 
                 if (fReindex)
                     pblocktree->WriteReindexing(true);