1 files changed, 79 insertions, 35 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index 8eec66286a..ab44e73d7c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -142,7 +142,7 @@ private:
       * ahead and mark descendants of invalid blocks as FAILED_CHILD at that time,
       * instead of putting things in this set.
       */
-    std::set<CBlockIndex*> g_failed_blocks;
+    std::set<CBlockIndex*> m_failed_blocks;
 
 public:
     CChain chainActive;
@@ -363,7 +363,7 @@ bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp, bool
 
     CBlockIndex* tip = chainActive.Tip();
     assert(tip != nullptr);
-    
+
     CBlockIndex index;
     index.pprev = tip;
     // CheckSequenceLocks() uses chainActive.Height()+1 to evaluate
@@ -1295,7 +1295,7 @@ void static InvalidChainFound(CBlockIndex* pindexNew)
 void CChainState::InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
     if (!state.CorruptionPossible()) {
         pindex->nStatus |= BLOCK_FAILED_VALID;
-        g_failed_blocks.insert(pindex);
+        m_failed_blocks.insert(pindex);
         setDirtyBlockIndex.insert(pindex);
         setBlockIndexCandidates.erase(pindex);
         InvalidChainFound(pindex);
@@ -1624,22 +1624,27 @@ void static FlushBlockFile(bool fFinalize = false)
     LOCK(cs_LastBlockFile);
 
     CDiskBlockPos posOld(nLastBlockFile, 0);
+    bool status = true;
 
     FILE *fileOld = OpenBlockFile(posOld);
     if (fileOld) {
         if (fFinalize)
-            TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nSize);
-        FileCommit(fileOld);
+            status &= TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nSize);
+        status &= FileCommit(fileOld);
         fclose(fileOld);
     }
 
     fileOld = OpenUndoFile(posOld);
     if (fileOld) {
         if (fFinalize)
-            TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nUndoSize);
-        FileCommit(fileOld);
+            status &= TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nUndoSize);
+        status &= FileCommit(fileOld);
         fclose(fileOld);
     }
+
+    if (!status) {
+        AbortNode("Flushing block file to disk failed. This is likely the result of an I/O error.");
+    }
 }
 
 static bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
@@ -1735,16 +1740,38 @@ public:
 // Protected by cs_main
 static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS];
 
+// 0.13.0 was shipped with a segwit deployment defined for testnet, but not for
+// mainnet. We no longer need to support disabling the segwit deployment
+// except for testing purposes, due to limitations of the functional test
+// environment. See test/functional/p2p-segwit.py.
+static bool IsScriptWitnessEnabled(const Consensus::Params& params)
+{
+    return params.vDeployments[Consensus::DEPLOYMENT_SEGWIT].nTimeout != 0;
+}
+
 static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consensus::Params& consensusparams) {
     AssertLockHeld(cs_main);
 
     unsigned int flags = SCRIPT_VERIFY_NONE;
 
-    // Start enforcing P2SH (BIP16)
-    if (pindex->nHeight >= consensusparams.BIP16Height) {
+    // BIP16 didn't become active until Apr 1 2012 (on mainnet, and
+    // retroactively applied to testnet)
+    // However, only one historical block violated the P2SH rules (on both
+    // mainnet and testnet), so for simplicity, always leave P2SH
+    // on except for the one violating block.
+    if (consensusparams.BIP16Exception.IsNull() || // no bip16 exception on this chain
+        pindex->phashBlock == nullptr || // this is a new candidate block, eg from TestBlockValidity()
+        *pindex->phashBlock != consensusparams.BIP16Exception) // this block isn't the historical exception
+    {
         flags |= SCRIPT_VERIFY_P2SH;
     }
 
+    // Enforce WITNESS rules whenever P2SH is in effect (and the segwit
+    // deployment is defined).
+    if (flags & SCRIPT_VERIFY_P2SH && IsScriptWitnessEnabled(consensusparams)) {
+        flags |= SCRIPT_VERIFY_WITNESS;
+    }
+
     // Start enforcing the DERSIG (BIP66) rule
     if (pindex->nHeight >= consensusparams.BIP66Height) {
         flags |= SCRIPT_VERIFY_DERSIG;
@@ -1760,9 +1787,7 @@ static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consens
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
-    // Start enforcing WITNESS rules using versionbits logic.
-    if (IsWitnessEnabled(pindex->pprev, consensusparams)) {
-        flags |= SCRIPT_VERIFY_WITNESS;
+    if (IsNullDummyEnabled(pindex->pprev, consensusparams)) {
         flags |= SCRIPT_VERIFY_NULLDUMMY;
     }
 
@@ -2190,14 +2215,18 @@ bool static FlushStateToDisk(const CChainParams& chainparams, CValidationState &
 void FlushStateToDisk() {
     CValidationState state;
     const CChainParams& chainparams = Params();
-    FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS);
+    if (!FlushStateToDisk(chainparams, state, FlushStateMode::ALWAYS)) {
+        LogPrintf("%s: failed to flush state (%s)\n", __func__, FormatStateMessage(state));
+    }
 }
 
 void PruneAndFlush() {
     CValidationState state;
     fCheckForPruning = true;
     const CChainParams& chainparams = Params();
-    FlushStateToDisk(chainparams, state, FlushStateMode::NONE);
+    if (!FlushStateToDisk(chainparams, state, FlushStateMode::NONE)) {
+        LogPrintf("%s: failed to flush state (%s)\n", __func__, FormatStateMessage(state));
+    }
 }
 
 static void DoWarning(const std::string& strWarning)
@@ -2691,18 +2720,17 @@ bool CChainState::ActivateBestChain(CValidationState &state, const CChainParams&
                 assert(trace.pblock && trace.pindex);
                 GetMainSignals().BlockConnected(trace.pblock, trace.pindex, trace.conflictedTxs);
             }
-        }
-        // When we reach this point, we switched to a new tip (stored in pindexNewTip).
-
-        // Notifications/callbacks that can run without cs_main
 
-        // Notify external listeners about the new tip.
-        GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload);
+            // Notify external listeners about the new tip.
+            // Enqueue while holding cs_main to ensure that UpdatedBlockTip is called in the order in which blocks are connected
+            GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload);
 
-        // Always notify the UI if a new block tip was connected
-        if (pindexFork != pindexNewTip) {
-            uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip);
+            // Always notify the UI if a new block tip was connected
+            if (pindexFork != pindexNewTip) {
+                uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip);
+            }
         }
+        // When we reach this point, we switched to a new tip (stored in pindexNewTip).
 
         if (nStopAtHeight && pindexNewTip && pindexNewTip->nHeight >= nStopAtHeight) StartShutdown();
 
@@ -2797,7 +2825,7 @@ bool CChainState::InvalidateBlock(CValidationState& state, const CChainParams& c
     pindex->nStatus |= BLOCK_FAILED_VALID;
     setDirtyBlockIndex.insert(pindex);
     setBlockIndexCandidates.erase(pindex);
-    g_failed_blocks.insert(pindex);
+    m_failed_blocks.insert(pindex);
 
     // DisconnectTip will add transactions to disconnectpool; try to add these
     // back to the mempool.
@@ -2843,7 +2871,7 @@ bool CChainState::ResetBlockFailureFlags(CBlockIndex *pindex) {
                 // Reset invalid block marker if it was pointing to one of those.
                 pindexBestInvalid = nullptr;
             }
-            g_failed_blocks.erase(it->second);
+            m_failed_blocks.erase(it->second);
         }
         it++;
     }
@@ -3113,6 +3141,12 @@ bool IsWitnessEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& pa
     return (VersionBitsState(pindexPrev, params, Consensus::DEPLOYMENT_SEGWIT, versionbitscache) == ThresholdState::ACTIVE);
 }
 
+bool IsNullDummyEnabled(const CBlockIndex* pindexPrev, const Consensus::Params& params)
+{
+    LOCK(cs_main);
+    return (VersionBitsState(pindexPrev, params, Consensus::DEPLOYMENT_SEGWIT, versionbitscache) == ThresholdState::ACTIVE);
+}
+
 // Compute at which vout of the block's coinbase transaction the witness
 // commitment occurs, or -1 if not found.
 static int GetWitnessCommitmentIndex(const CBlock& block)
@@ -3340,7 +3374,7 @@ bool CChainState::AcceptBlockHeader(const CBlockHeader& block, CValidationState&
         // has been found invalid (g_failed_blocks), then mark pindexPrev and any blocks
         // between them as failed.
         if (!pindexPrev->IsValid(BLOCK_VALID_SCRIPTS)) {
-            for (const CBlockIndex* failedit : g_failed_blocks) {
+            for (const CBlockIndex* failedit : m_failed_blocks) {
                 if (pindexPrev->GetAncestor(failedit->nHeight) == failedit) {
                     assert(failedit->nStatus & BLOCK_FAILED_VALID);
                     CBlockIndex* invalid_walk = pindexPrev;
@@ -3506,7 +3540,7 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
         }
         if (!ret) {
             GetMainSignals().BlockChecked(*pblock, state);
-            return error("%s: AcceptBlock FAILED (%s)", __func__, state.GetDebugMessage());
+            return error("%s: AcceptBlock FAILED (%s)", __func__, FormatStateMessage(state));
         }
     }
 
@@ -3514,7 +3548,7 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
 
     CValidationState state; // Only used to report errors, not invalidity - ignore it
     if (!g_chainstate.ActivateBestChain(state, chainparams, pblock))
-        return error("%s: ActivateBestChain failed", __func__);
+        return error("%s: ActivateBestChain failed (%s)", __func__, FormatStateMessage(state));
 
     return true;
 }
@@ -3632,7 +3666,9 @@ void PruneBlockFilesManual(int nManualPruneHeight)
 {
     CValidationState state;
     const CChainParams& chainparams = Params();
-    FlushStateToDisk(chainparams, state, FlushStateMode::NONE, nManualPruneHeight);
+    if (!FlushStateToDisk(chainparams, state, FlushStateMode::NONE, nManualPruneHeight)) {
+        LogPrintf("%s: failed to flush state (%s)\n", __func__, FormatStateMessage(state));
+    }
 }
 
 /**
@@ -3886,6 +3922,7 @@ bool LoadChainTip(const CChainParams& chainparams)
         LogPrintf("%s: Connecting genesis block...\n", __func__);
         CValidationState state;
         if (!ActivateBestChain(state, chainparams)) {
+            LogPrintf("%s: failed to activate chain (%s)\n", __func__, FormatStateMessage(state));
             return false;
         }
     }
@@ -4000,7 +4037,7 @@ bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview,
             if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
                 return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
             if (!g_chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
-                return error("VerifyDB(): *** found unconnectable block at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
+                return error("VerifyDB(): *** found unconnectable block at %d, hash=%s (%s)", pindex->nHeight, pindex->GetBlockHash().ToString(), FormatStateMessage(state));
         }
     }
 
@@ -4108,6 +4145,9 @@ bool CChainState::RewindBlockIndex(const CChainParams& params)
 
     int nHeight = 1;
     while (nHeight <= chainActive.Height()) {
+        // Although SCRIPT_VERIFY_WITNESS is now generally enforced on all
+        // blocks in ConnectBlock, we don't need to go back and
+        // re-download/re-verify blocks from before segwit actually activated.
         if (IsWitnessEnabled(chainActive[nHeight - 1], params.GetConsensus()) && !(chainActive[nHeight]->nStatus & BLOCK_OPT_WITNESS)) {
             break;
         }
@@ -4127,11 +4167,13 @@ bool CChainState::RewindBlockIndex(const CChainParams& params)
             break;
         }
         if (!DisconnectTip(state, params, nullptr)) {
-            return error("RewindBlockIndex: unable to disconnect block at height %i", pindex->nHeight);
+            return error("RewindBlockIndex: unable to disconnect block at height %i (%s)", pindex->nHeight, FormatStateMessage(state));
         }
         // Occasionally flush state to disk.
-        if (!FlushStateToDisk(params, state, FlushStateMode::PERIODIC))
+        if (!FlushStateToDisk(params, state, FlushStateMode::PERIODIC)) {
+            LogPrintf("RewindBlockIndex: unable to flush state to disk (%s)\n", FormatStateMessage(state));
             return false;
+        }
     }
 
     // Reduce validity flag and have-data flags.
@@ -4197,6 +4239,7 @@ bool RewindBlockIndex(const CChainParams& params) {
         // it'll get called a bunch real soon.
         CValidationState state;
         if (!FlushStateToDisk(params, state, FlushStateMode::ALWAYS)) {
+            LogPrintf("RewindBlockIndex: unable to flush state to disk (%s)\n", FormatStateMessage(state));
             return false;
         }
     }
@@ -4206,7 +4249,7 @@ bool RewindBlockIndex(const CChainParams& params) {
 
 void CChainState::UnloadBlockIndex() {
     nBlockSequenceId = 1;
-    g_failed_blocks.clear();
+    m_failed_blocks.clear();
     setBlockIndexCandidates.clear();
 }
 
@@ -4283,7 +4326,7 @@ bool CChainState::LoadGenesisBlock(const CChainParams& chainparams)
         CBlockIndex *pindex = AddToBlockIndex(block);
         CValidationState state;
         if (!ReceivedBlockTransactions(block, state, pindex, blockPos, chainparams.GetConsensus()))
-            return error("%s: genesis block not accepted", __func__);
+            return error("%s: genesis block not accepted (%s)", __func__, FormatStateMessage(state));
     } catch (const std::runtime_error& e) {
         return error("%s: failed to write genesis block: %s", __func__, e.what());
     }
@@ -4748,7 +4791,8 @@ bool DumpMempool(void)
         }
 
         file << mapDeltas;
-        FileCommit(file.Get());
+        if (!FileCommit(file.Get()))
+            throw std::runtime_error("FileCommit failed");
         file.fclose();
         RenameOver(GetDataDir() / "mempool.dat.new", GetDataDir() / "mempool.dat");
         int64_t last = GetTimeMicros();