From fdc329376c8a0fa4dffd0cd2599a494a64c38472 Mon Sep 17 00:00:00 2001
From: practicalswift <practicalswift@users.noreply.github.com>
Date: Mon, 28 Aug 2017 09:24:17 +0200
Subject: Document assumptions that are being made to avoid NULL pointer
 dereferences

---
 src/qt/walletframe.cpp | 2 ++
 src/validation.cpp     | 2 ++
 src/wallet/wallet.cpp  | 1 +
 3 files changed, 5 insertions(+)

diff --git a/src/qt/walletframe.cpp b/src/qt/walletframe.cpp
index f3183320f0..714a594318 100644
--- a/src/qt/walletframe.cpp
+++ b/src/qt/walletframe.cpp
@@ -7,6 +7,7 @@
 #include "bitcoingui.h"
 #include "walletview.h"
 
+#include <cassert>
 #include <cstdio>
 
 #include <QHBoxLayout>
@@ -69,6 +70,7 @@ bool WalletFrame::setCurrentWallet(const QString& name)
 
     WalletView *walletView = mapWalletViews.value(name);
     walletStack->setCurrentWidget(walletView);
+    assert(walletView);
     walletView->updateEncryptionStatus();
     return true;
 }
diff --git a/src/validation.cpp b/src/validation.cpp
index 3b9636839d..939921d677 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1710,6 +1710,7 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
     // before the first had been spent.  Since those coinbases are sufficiently buried its no longer possible to create further
     // duplicate transactions descending from the known pairs either.
     // If we're on the known chain at height greater than where BIP34 activated, we can save the db accesses needed for the BIP30 check.
+    assert(pindex->pprev);
     CBlockIndex *pindexBIP34height = pindex->pprev->GetAncestor(chainparams.GetConsensus().BIP34Height);
     //Only continue to enforce if we're below BIP34 activation height or the block hash at that height doesn't correspond.
     fEnforceBIP30 = fEnforceBIP30 && (!pindexBIP34height || !(pindexBIP34height->GetBlockHash() == chainparams.GetConsensus().BIP34Hash));
@@ -1849,6 +1850,7 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
         if (!pblocktree->WriteTxIndex(vPos))
             return AbortNode(state, "Failed to write transaction index");
 
+    assert(pindex->phashBlock);
     // add this block to the view's block chain
     view.SetBestBlock(pindex->GetBlockHash());
 
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index d1d2060b0c..36d6ce0007 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -519,6 +519,7 @@ void CWallet::SyncMetaData(std::pair<TxSpends::iterator, TxSpends::iterator> ran
         const uint256& hash = it->second;
         CWalletTx* copyTo = &mapWallet[hash];
         if (copyFrom == copyTo) continue;
+        assert(copyFrom && "Oldest wallet transaction in range assumed to have been found.");
         if (!copyFrom->IsEquivalentTo(*copyTo)) continue;
         copyTo->mapValue = copyFrom->mapValue;
         copyTo->vOrderForm = copyFrom->vOrderForm;
-- 
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