From 97703e4c7d9e84123bef2aea88866125d2fb933c Mon Sep 17 00:00:00 2001
From: Christopher Jeffrey <chjjeffrey@gmail.com>
Date: Thu, 17 Nov 2016 03:02:46 -0800
Subject: [PATCH] chain: only expose state if block is successfully written.

---
 lib/chain/chain.js | 37 +++++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/lib/chain/chain.js b/lib/chain/chain.js
index 8cd23c73..27007cfa 100644
--- a/lib/chain/chain.js
+++ b/lib/chain/chain.js
@@ -249,17 +249,18 @@ Chain.prototype._close = function close() {
  */
 
 Chain.prototype.verifyContext = co(function* verifyContext(block, prev) {
-  var state = yield this.verify(block, prev);
-  var view;
+  var state, view;
 
+  // Initial non-contextual verification.
+  state = yield this.verify(block, prev);
+
+  // BIP30 - Verify there are no duplicate txids.
   yield this.verifyDuplicates(block, prev, state);
 
+  // Verify scripts, spend and add coins.
   view = yield this.verifyInputs(block, prev, state);
 
-  // Expose the state globally.
-  this.state = state;
-
-  return view;
+  return new ContextResult(view, state);
 });
 
 /**
@@ -869,7 +870,7 @@ Chain.prototype.disconnect = co(function* disconnect(entry) {
 
 Chain.prototype.reconnect = co(function* reconnect(entry) {
   var block = yield this.db.getBlock(entry.hash);
-  var prev, view;
+  var prev, result;
 
   if (this.options.spv) {
     assert(!block);
@@ -882,7 +883,7 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
   assert(prev);
 
   try {
-    view = yield this.verifyContext(block, prev);
+    result = yield this.verifyContext(block, prev);
   } catch (e) {
     if (e.type === 'VerifyError') {
       if (!e.malleated)
@@ -892,10 +893,11 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
     throw e;
   }
 
-  yield this.db.reconnect(entry, block, view);
+  yield this.db.reconnect(entry, block, result.view);
 
   this.tip = entry;
   this.height = entry.height;
+  this.state = result.state;
 
   this.bestHeight = entry.height;
   this.network.updateHeight(entry.height);
@@ -918,7 +920,7 @@ Chain.prototype.reconnect = co(function* reconnect(entry) {
  */
 
 Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev) {
-  var view;
+  var result;
 
   // A higher fork has arrived.
   // Time to reorganize the chain.
@@ -938,7 +940,7 @@ Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev) {
   // now that we're certain its previous
   // block is in the chain.
   try {
-    view = yield this.verifyContext(block, prev);
+    result = yield this.verifyContext(block, prev);
   } catch (e) {
     // Couldn't verify block.
     // Revert the height.
@@ -954,10 +956,12 @@ Chain.prototype.setBestChain = co(function* setBestChain(entry, block, prev) {
   }
 
   // Save block and connect inputs.
-  yield this.db.save(entry, block, view);
+  yield this.db.save(entry, block, result.view);
 
+  // Expose the new state.
   this.tip = entry;
   this.height = entry.height;
+  this.state = result.state;
 
   this.emit('tip', entry);
 });
@@ -2290,6 +2294,15 @@ function LockTimes(height, time) {
   this.time = time;
 }
 
+/*
+ * ContextResult
+ */
+
+function ContextResult(view, state) {
+  this.view = view;
+  this.state = state;
+}
+
 /*
  * Expose
  */