From d67a0e207c41aeee7d578bbe94b0314eccc640d3 Mon Sep 17 00:00:00 2001
From: Dave Collins <davec@conformal.com>
Date: Thu, 29 Jan 2015 00:11:19 -0600
Subject: [PATCH] Update for recent ScriptBuilder API change.

---
 mining.go    | 18 ++++++++++++++----
 rpcserver.go | 16 ++++++++++++++--
 2 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/mining.go b/mining.go
index 9fc02f89..4f78db9c 100644
--- a/mining.go
+++ b/mining.go
@@ -200,7 +200,7 @@ func mergeTxStore(txStoreA btcchain.TxStore, txStoreB btcchain.TxStore) {
 // signature script of the coinbase transaction of a new block.  In particular,
 // it starts with the block height that is required by version 2 blocks and adds
 // the extra nonce as well as additional coinbase flags.
-func standardCoinbaseScript(nextBlockHeight int64, extraNonce uint64) []byte {
+func standardCoinbaseScript(nextBlockHeight int64, extraNonce uint64) ([]byte, error) {
 	return btcscript.NewScriptBuilder().AddInt64(nextBlockHeight).
 		AddUint64(extraNonce).AddData([]byte(coinbaseFlags)).Script()
 }
@@ -223,8 +223,12 @@ func createCoinbaseTx(coinbaseScript []byte, nextBlockHeight int64, addr btcutil
 			return nil, err
 		}
 	} else {
+		var err error
 		scriptBuilder := btcscript.NewScriptBuilder()
-		pkScript = scriptBuilder.AddOp(btcscript.OP_TRUE).Script()
+		pkScript, err = scriptBuilder.AddOp(btcscript.OP_TRUE).Script()
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	tx := btcwire.NewMsgTx()
@@ -439,7 +443,10 @@ func NewBlockTemplate(mempool *txMemPool, payToAddress btcutil.Address) (*BlockT
 	// same value to the same public key address would otherwise be an
 	// identical transaction for block version 1).
 	extraNonce := uint64(0)
-	coinbaseScript := standardCoinbaseScript(nextBlockHeight, extraNonce)
+	coinbaseScript, err := standardCoinbaseScript(nextBlockHeight, extraNonce)
+	if err != nil {
+		return nil, err
+	}
 	coinbaseTx, err := createCoinbaseTx(coinbaseScript, nextBlockHeight,
 		payToAddress)
 	if err != nil {
@@ -841,7 +848,10 @@ func UpdateBlockTime(msgBlock *btcwire.MsgBlock, bManager *blockManager) error {
 // height.  It also recalculates and updates the new merkle root that results
 // from changing the coinbase script.
 func UpdateExtraNonce(msgBlock *btcwire.MsgBlock, blockHeight int64, extraNonce uint64) error {
-	coinbaseScript := standardCoinbaseScript(blockHeight, extraNonce)
+	coinbaseScript, err := standardCoinbaseScript(blockHeight, extraNonce)
+	if err != nil {
+		return err
+	}
 	if len(coinbaseScript) > btcchain.MaxCoinbaseScriptLen {
 		return fmt.Errorf("coinbase transaction script length "+
 			"of %d is out of range (min: %d, max: %d)",
diff --git a/rpcserver.go b/rpcserver.go
index 0215e36c..a1a000ed 100644
--- a/rpcserver.go
+++ b/rpcserver.go
@@ -92,8 +92,8 @@ var (
 	// overhead of creating a new object on every invocation for constant
 	// data.
 	gbtCoinbaseAux = &btcjson.GetBlockTemplateResultAux{
-		Flags: hex.EncodeToString(btcscript.NewScriptBuilder().
-			AddData([]byte(coinbaseFlags)).Script()),
+		Flags: hex.EncodeToString(builderScript(btcscript.
+			NewScriptBuilder().AddData([]byte(coinbaseFlags)))),
 	}
 
 	// gbtCapabilities describes additional capabilities returned with a
@@ -210,6 +210,18 @@ var rpcAskWallet = map[string]struct{}{
 // Commands that are temporarily unimplemented.
 var rpcUnimplemented = map[string]struct{}{}
 
+// builderScript is a convenience function which is used to for hard-coded
+// scripts built with the script builder.   Any errors are converted to a panic
+// since it is only, and must only, be used with hard-coded, and therefore,
+// known good, scripts.
+func builderScript(builder *btcscript.ScriptBuilder) []byte {
+	script, err := builder.Script()
+	if err != nil {
+		panic(err)
+	}
+	return script
+}
+
 // workStateBlockInfo houses information about how to reconstruct a block given
 // its template and signature script.
 type workStateBlockInfo struct {