Simplify DisconnectBlock arguments/return value

furszy · Fuzzbawls · commit 0f6676439fc5 · 2020-08-12T16:13:52.000-07:00
coming from btc@db994b2de93f52c9e7bed8529ca925de5064a46f Github-Pull: #1735 Rebased-From: 17e9b8e
diff --git a/src/main.cpp b/src/main.cpp
@@ -2023,41 +2023,55 @@ static bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const CO
     return fClean;
 }
 
-bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, CCoinsViewCache& view, bool* pfClean)
+enum DisconnectResult
+{
+    DISCONNECT_OK,      // All good.
+    DISCONNECT_UNCLEAN, // Rolled back, but UTXO set was inconsistent with block.
+    DISCONNECT_FAILED   // Something else went wrong.
+};
+
+/** Undo the effects of this block (with given index) on the UTXO set represented by coins.
+ *  When UNCLEAN or FAILED is returned, view is left in an indeterminate state. */
+DisconnectResult DisconnectBlock(CBlock& block, CBlockIndex* pindex, CCoinsViewCache& view)
 {
     AssertLockHeld(cs_main);
 
     if (pindex->GetBlockHash() != view.GetBestBlock())
         LogPrintf("%s : pindex=%s view=%s\n", __func__, pindex->GetBlockHash().GetHex(), view.GetBestBlock().GetHex());
     assert(pindex->GetBlockHash() == view.GetBestBlock());
 
-    if (pfClean)
-        *pfClean = false;
-
     bool fClean = true;
 
     CBlockUndo blockUndo;
     CAmount nValueOut = 0;
     CAmount nValueIn = 0;
     CDiskBlockPos pos = pindex->GetUndoPos();
-    if (pos.IsNull())
-        return error("DisconnectBlock() : no undo data available");
-    if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash()))
-        return error("DisconnectBlock() : failure reading undo data");
+    if (pos.IsNull()) {
+        error("DisconnectBlock() : no undo data available");
+        return DISCONNECT_FAILED;
+    }
+    if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash())) {
+        error("DisconnectBlock() : failure reading undo data");
+        return DISCONNECT_FAILED;
+    }
 
-    if (blockUndo.vtxundo.size() + 1 != block.vtx.size())
-        return error("DisconnectBlock() : block and undo data inconsistent");
+    if (blockUndo.vtxundo.size() + 1 != block.vtx.size()) {
+        error("DisconnectBlock() : block and undo data inconsistent");
+        return DISCONNECT_FAILED;
+    }
 
     //Track zPIV money supply
-    if (!UpdateZPIVSupplyDisconnect(block, pindex))
-        return error("%s: Failed to calculate new zPIV supply", __func__);
+    if (!UpdateZPIVSupplyDisconnect(block, pindex)) {
+        error("%s: Failed to calculate new zPIV supply", __func__);
+        return DISCONNECT_FAILED;
+    }
 
     // undo transactions in reverse order
     for (int i = block.vtx.size() - 1; i >= 0; i--) {
         const CTransaction& tx = block.vtx[i];
 
         if (!DisconnectZerocoinTx(tx, nValueIn, zerocoinDB))
-            return false;
+            return DISCONNECT_FAILED;
 
         nValueOut += tx.GetValueOut();
         uint256 hash = tx.GetHash();
@@ -2088,8 +2102,11 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
 
         // restore inputs
         const CTxUndo& txundo = blockUndo.vtxundo[i - 1];
-        if (txundo.vprevout.size() != tx.vin.size())
-            return error("DisconnectBlock() : transaction and undo data inconsistent - txundo.vprevout.siz=%d tx.vin.siz=%d", txundo.vprevout.size(), tx.vin.size());
+        if (txundo.vprevout.size() != tx.vin.size()) {
+            error("DisconnectBlock() : transaction and undo data inconsistent - txundo.vprevout.siz=%d tx.vin.siz=%d",
+                  txundo.vprevout.size(), tx.vin.size());
+            return DISCONNECT_FAILED;
+        }
         for (unsigned int j = tx.vin.size(); j-- > 0;) {
             const COutPoint& out = tx.vin[j].prevout;
             const CTxInUndo& undo = txundo.vprevout[j];
@@ -2114,12 +2131,7 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
         DataBaseAccChecksum(pindex, false);
     }
 
-    if (pfClean) {
-        *pfClean = fClean;
-        return true;
-    }
-
-    return fClean;
+    return fClean ? DISCONNECT_OK : DISCONNECT_UNCLEAN;
 }
 
 void static FlushBlockFile(bool fFinalize = false)
@@ -2665,7 +2677,7 @@ bool static DisconnectTip(CValidationState& state)
     int64_t nStart = GetTimeMicros();
     {
         CCoinsViewCache view(pcoinsTip);
-        if (!DisconnectBlock(block, state, pindexDelete, view))
+        if (DisconnectBlock(block, pindexDelete, view) != DISCONNECT_OK)
             return error("DisconnectTip() : DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
         assert(view.Flush());
     }
@@ -4430,15 +4442,18 @@ bool CVerifyDB::VerifyDB(CCoinsView* coinsview, int nCheckLevel, int nCheckDepth
         }
         // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
         if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
-            bool fClean = true;
-            if (!DisconnectBlock(block, state, pindex, coins, &fClean))
-                return error("%s: *** irrecoverable inconsistency in block data at %d, hash=%s", __func__, pindex->nHeight, pindex->GetBlockHash().ToString());
+            DisconnectResult res = DisconnectBlock(block, pindex, coins);
+            if (res == DISCONNECT_FAILED) {
+                return error("%s: *** irrecoverable inconsistency in block data at %d, hash=%s", __func__,
+                             pindex->nHeight, pindex->GetBlockHash().ToString());
+            }
             pindexState = pindex->pprev;
-            if (!fClean) {
+            if (res == DISCONNECT_UNCLEAN) {
                 nGoodTransactions = 0;
                 pindexFailure = pindex;
-            } else
+            } else {
                 nGoodTransactions += block.vtx.size();
+            }
         }
         if (ShutdownRequested())
             return true;
