From d7502debba9e7ae4ff9bb125cfa76bd0fc3b99ee Mon Sep 17 00:00:00 2001
From: Roman Khimov <roman@nspcc.ru>
Date: Tue, 3 Nov 2020 22:50:40 +0300
Subject: [PATCH] core: adjust storage update fees

Follow neo-project/neo#2033.
---
 pkg/core/interop_system.go      | 8 ++++++--
 pkg/core/interop_system_test.go | 4 +++-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/pkg/core/interop_system.go b/pkg/core/interop_system.go
index c1f43d023..509d76344 100644
--- a/pkg/core/interop_system.go
+++ b/pkg/core/interop_system.go
@@ -396,8 +396,12 @@ func putWithContextAndFlags(ic *interop.Context, stc *StorageContext, key []byte
 	if si == nil {
 		si = &state.StorageItem{}
 		sizeInc = len(key) + len(value)
-	} else if len(value) > len(si.Value) {
-		sizeInc = len(value) - len(si.Value)
+	} else if len(value) != 0 {
+		if len(value) <= len(si.Value) {
+			sizeInc = (len(value)-1)/4 + 1
+		} else {
+			sizeInc = (len(si.Value)-1)/4 + 1 + len(value) - len(si.Value)
+		}
 	}
 	if !ic.VM.AddGas(int64(sizeInc) * StoragePrice) {
 		return errGasLimitExceeded
diff --git a/pkg/core/interop_system_test.go b/pkg/core/interop_system_test.go
index 00d5644ea..0eaf8e274 100644
--- a/pkg/core/interop_system_test.go
+++ b/pkg/core/interop_system_test.go
@@ -364,7 +364,9 @@ func TestStoragePut(t *testing.T) {
 			err := storagePut(ic)
 			require.True(t, errors.Is(err, errGasLimitExceeded), "got: %v", err)
 		})
-		initVM(t, []byte{4}, []byte{5, 6, 7, 8}, 2*StoragePrice)
+		initVM(t, []byte{4}, []byte{5, 6, 7, 8}, 3*StoragePrice)
+		require.NoError(t, storagePut(ic))
+		initVM(t, []byte{4}, []byte{5, 6}, StoragePrice)
 		require.NoError(t, storagePut(ic))
 	})
 }