Split logic to undo txin's off DisconnectBlock

coming from btc@eb1c2cd37f75cf4d0e85970932b9774b2d073225

Author: furszy

src/main.cpp

@@ -1990,6 +1990,39 @@ bool UndoReadFromDisk(CBlockUndo& blockundo, const CDiskBlockPos& pos, const uin
 
 } // anon namespace
 
+/**
+ * Apply the undo operation of a CTxInUndo to the given chain state.
+ * @param undo The undo object.
+ * @param view The coins view to which to apply the changes.
+ * @param out The out point that corresponds to the tx input.
+ * @return True on success.
+ */
+static bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const COutPoint& out)
+{
+    bool fClean = true;
+
+    CCoinsModifier coins = view.ModifyCoins(out.hash);
+    if (undo.nHeight != 0) {
+        // undo data contains height: this is the last output of the prevout tx being spent
+        if (!coins->IsPruned())
+            fClean = fClean && error("%s: undo data overwriting existing transaction", __func__);
+        coins->Clear();
+        coins->fCoinBase = undo.fCoinBase;
+        coins->nHeight = undo.nHeight;
+        coins->nVersion = undo.nVersion;
+    } else {
+        if (coins->IsPruned())
+            fClean = fClean && error("%s: undo data adding output to missing transaction", __func__);
+    }
+    if (coins->IsAvailable(out.n))
+        fClean = fClean && error("%s: undo data overwriting existing output", __func__);
+    if (coins->vout.size() < out.n+1)
+        coins->vout.resize(out.n+1);
+    coins->vout[out.n] = undo.txout;
+
+    return fClean;
+}
+
 bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex, CCoinsViewCache& view, bool* pfClean)
 {
     AssertLockHeld(cs_main);
@@ -2031,11 +2064,8 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
 
 
         // Check that all outputs are available and match the outputs in the block itself
-        // exactly. Note that transactions with only provably unspendable outputs won't
-        // have outputs available even in the block itself, so we handle that case
-        // specially with outsEmpty.
+        // exactly.
         {
-            CCoins outsEmpty;
             CCoinsModifier outs = view.ModifyCoins(hash);
             outs->ClearUnspendable();
 
@@ -2063,24 +2093,8 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
         for (unsigned int j = tx.vin.size(); j-- > 0;) {
             const COutPoint& out = tx.vin[j].prevout;
             const CTxInUndo& undo = txundo.vprevout[j];
-            CCoinsModifier coins = view.ModifyCoins(out.hash);
-            if (undo.nHeight != 0) {
-                // undo data contains height: this is the last output of the prevout tx being spent
-                if (!coins->IsPruned())
-                    fClean = fClean && error("DisconnectBlock() : undo data overwriting existing transaction");
-                coins->Clear();
-                coins->fCoinBase = undo.fCoinBase;
-                coins->nHeight = undo.nHeight;
-                coins->nVersion = undo.nVersion;
-            } else {
-                if (coins->IsPruned())
-                    fClean = fClean && error("DisconnectBlock() : undo data adding output to missing transaction");
-            }
-            if (coins->IsAvailable(out.n))
-                fClean = fClean && error("DisconnectBlock() : undo data overwriting existing output");
-            if (coins->vout.size() < out.n + 1)
-                coins->vout.resize(out.n + 1);
-            coins->vout[out.n] = undo.txout;
+            if (!ApplyTxInUndo(undo, view, out))
+                fClean = false;
         }
 
         if (view.HaveInputs(tx))
@@ -2103,9 +2117,9 @@ bool DisconnectBlock(CBlock& block, CValidationState& state, CBlockIndex* pindex
     if (pfClean) {
         *pfClean = fClean;
         return true;
-    } else {
-        return fClean;
     }
+
+    return fClean;
 }
 
 void static FlushBlockFile(bool fFinalize = false)