refactor: wrap CCoinsViewCursor in unique_ptr

Specifically with CCoinsViewDB, if a raw cursor is allocated and
not freed, a cryptic leveldb assertion failure occurs on
CCoinsViewDB destruction.

See: https://github.com/google/leveldb/issues/142#issuecomment-414418135

1 files changed, 2 insertions, 2 deletions

diff --git a/src/coins.cpp b/src/coins.cpp
index d52851cadd..ce0b131de6 100644
--- a/src/coins.cpp
+++ b/src/coins.cpp
@@ -13,7 +13,7 @@ bool CCoinsView::GetCoin(const COutPoint &outpoint, Coin &coin) const { return f
 uint256 CCoinsView::GetBestBlock() const { return uint256(); }
 std::vector<uint256> CCoinsView::GetHeadBlocks() const { return std::vector<uint256>(); }
 bool CCoinsView::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return false; }
-CCoinsViewCursor *CCoinsView::Cursor() const { return nullptr; }
+std::unique_ptr<CCoinsViewCursor> CCoinsView::Cursor() const { return nullptr; }
 
 bool CCoinsView::HaveCoin(const COutPoint &outpoint) const
 {
@@ -28,7 +28,7 @@ uint256 CCoinsViewBacked::GetBestBlock() const { return base->GetBestBlock(); }
 std::vector<uint256> CCoinsViewBacked::GetHeadBlocks() const { return base->GetHeadBlocks(); }
 void CCoinsViewBacked::SetBackend(CCoinsView &viewIn) { base = &viewIn; }
 bool CCoinsViewBacked::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) { return base->BatchWrite(mapCoins, hashBlock); }
-CCoinsViewCursor *CCoinsViewBacked::Cursor() const { return base->Cursor(); }
+std::unique_ptr<CCoinsViewCursor> CCoinsViewBacked::Cursor() const { return base->Cursor(); }
 size_t CCoinsViewBacked::EstimateSize() const { return base->EstimateSize(); }
 
 CCoinsViewCache::CCoinsViewCache(CCoinsView *baseIn) : CCoinsViewBacked(baseIn), cachedCoinsUsage(0) {}