core: do not copy key/value results got from MemCachedStore.Seek

They are already copied inside the MemCachedStore.Seek, so that
persistent storage  can't change them anymore.

pkg/core/blockchain.go

@@ -490,9 +490,8 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 		// Firstly, remove all old genesis-related items.
 		b := bc.dao.Store.Batch()
 		bc.dao.Store.Seek([]byte{byte(storage.STStorage)}, func(k, _ []byte) {
-			// Must copy here, #1468.
-			key := slice.Copy(k)
-			b.Delete(key)
+			// #1468, but don't need to copy here, because it is done by Store.
+			b.Delete(k)
 		})
 		b.Put(jumpStageKey, []byte{byte(oldStorageItemsRemoved)})
 		err := bc.dao.Store.PutBatch(b)
@@ -509,14 +508,12 @@ func (bc *Blockchain) jumpToStateInternal(p uint32, stage stateJumpStage) error
 				if count >= maxStorageBatchSize {
 					return
 				}
-				// Must copy here, #1468.
-				oldKey := slice.Copy(k)
-				b.Delete(oldKey)
+				// #1468, but don't need to copy here, because it is done by Store.
+				b.Delete(k)
 				key := make([]byte, len(k))
 				key[0] = byte(storage.STStorage)
 				copy(key[1:], k[1:])
-				value := slice.Copy(v)
-				b.Put(key, value)
+				b.Put(key, slice.Copy(v))
 				count += 2
 			})
 			if count > 0 {

pkg/core/dao/dao.go

@@ -16,7 +16,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/util"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 )
 
 // HasTransaction errors.
@@ -324,12 +323,10 @@ func (dao *Simple) GetStorageItemsWithPrefix(id int32, prefix []byte) ([]state.S
 
 	saveToArr := func(k, v []byte) {
 		// Cut prefix and hash.
-		// Must copy here, #1468.
-		key := slice.Copy(k)
-		val := slice.Copy(v)
+		// #1468, but don't need to copy here, because it is done by Store.
 		siArr = append(siArr, state.StorageItemWithKey{
-			Key:  key,
-			Item: state.StorageItem(val),
+			Key:  k,
+			Item: state.StorageItem(v),
 		})
 	}
 	dao.Seek(id, prefix, saveToArr)

pkg/core/stateroot/module.go

@@ -13,7 +13,6 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/core/storage"
 	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
 	"github.com/nspcc-dev/neo-go/pkg/util"
-	"github.com/nspcc-dev/neo-go/pkg/util/slice"
 	"go.uber.org/atomic"
 	"go.uber.org/zap"
 )
@@ -147,9 +146,8 @@ func (s *Module) CleanStorage() error {
 	//
 	b := s.Store.Batch()
 	s.Store.Seek([]byte{byte(storage.DataMPT)}, func(k, _ []byte) {
-		// Must copy here, #1468.
-		key := slice.Copy(k)
-		b.Delete(key)
+		// #1468, but don't need to copy here, because it is done by Store.
+		b.Delete(k)
 	})
 	err = s.Store.PutBatch(b)
 	if err != nil {