From da85a1d80b91c6c619e97a7d5435818363a4e215 Mon Sep 17 00:00:00 2001
From: Larry Ruane <larry@z.cash>
Date: Mon, 7 Oct 2019 14:00:10 -0600
Subject: [PATCH] GetDisplayPrevHash() should not change its argument

---
 parser/block.go | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/parser/block.go b/parser/block.go
index 0d60fed..1c02235 100644
--- a/parser/block.go
+++ b/parser/block.go
@@ -44,13 +44,14 @@ func (b *Block) GetEncodableHash() []byte {
 }
 
 func (b *Block) GetDisplayPrevHash() []byte {
-	h := b.hdr.HashPrevBlock
+	rhash := make([]byte, len(b.hdr.HashPrevBlock))
+	copy(rhash, b.hdr.HashPrevBlock)
 	// Reverse byte order
-	for i := 0; i < len(h)/2; i++ {
-		j := len(h) - 1 - i
-		h[i], h[j] = h[j], h[i]
+	for i := 0; i < len(rhash)/2; i++ {
+		j := len(rhash) - 1 - i
+		rhash[i], rhash[j] = rhash[j], rhash[i]
 	}
-	return h
+	return rhash
 }
 
 func (b *Block) HasSaplingTransactions() bool {