From 5dea0f2aa48a12e671dfa906896031db2379de8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Fri, 24 Nov 2017 11:02:25 +0200
Subject: [PATCH] core/state: copy trie too, not just content

---
 core/state/statedb.go      |  2 +-
 core/state/statedb_test.go | 51 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/core/state/statedb.go b/core/state/statedb.go
index 002fa6249..de9fb367d 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -453,7 +453,7 @@ func (self *StateDB) Copy() *StateDB {
 	// Copy all the basic fields, initialize the memory ones
 	state := &StateDB{
 		db:                self.db,
-		trie:              self.trie,
+		trie:              self.db.CopyTrie(self.trie),
 		stateObjects:      make(map[common.Address]*stateObject, len(self.stateObjectsDirty)),
 		stateObjectsDirty: make(map[common.Address]struct{}, len(self.stateObjectsDirty)),
 		refund:            new(big.Int).Set(self.refund),
diff --git a/core/state/statedb_test.go b/core/state/statedb_test.go
index b2bd18e65..e9944cd74 100644
--- a/core/state/statedb_test.go
+++ b/core/state/statedb_test.go
@@ -117,6 +117,57 @@ func TestIntermediateLeaks(t *testing.T) {
 	}
 }
 
+// TestCopy tests that copying a statedb object indeed makes the original and
+// the copy independent of each other. This test is a regression test against
+// https://github.com/ethereum/go-ethereum/pull/15549.
+func TestCopy(t *testing.T) {
+	// Create a random state test to copy and modify "independently"
+	mem, _ := ethdb.NewMemDatabase()
+	orig, _ := New(common.Hash{}, NewDatabase(mem))
+
+	for i := byte(0); i < 255; i++ {
+		obj := orig.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
+		obj.AddBalance(big.NewInt(int64(i)))
+		orig.updateStateObject(obj)
+	}
+	orig.Finalise(false)
+
+	// Copy the state, modify both in-memory
+	copy := orig.Copy()
+
+	for i := byte(0); i < 255; i++ {
+		origObj := orig.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
+		copyObj := copy.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
+
+		origObj.AddBalance(big.NewInt(2 * int64(i)))
+		copyObj.AddBalance(big.NewInt(3 * int64(i)))
+
+		orig.updateStateObject(origObj)
+		copy.updateStateObject(copyObj)
+	}
+	// Finalise the changes on both concurrently
+	done := make(chan struct{})
+	go func() {
+		orig.Finalise(true)
+		close(done)
+	}()
+	copy.Finalise(true)
+	<-done
+
+	// Verify that the two states have been updated independently
+	for i := byte(0); i < 255; i++ {
+		origObj := orig.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
+		copyObj := copy.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
+
+		if want := big.NewInt(3 * int64(i)); origObj.Balance().Cmp(want) != 0 {
+			t.Errorf("orig obj %d: balance mismatch: have %v, want %v", i, origObj.Balance(), want)
+		}
+		if want := big.NewInt(4 * int64(i)); copyObj.Balance().Cmp(want) != 0 {
+			t.Errorf("copy obj %d: balance mismatch: have %v, want %v", i, copyObj.Balance(), want)
+		}
+	}
+}
+
 func TestSnapshotRandom(t *testing.T) {
 	config := &quick.Config{MaxCount: 1000}
 	err := quick.Check((*snapshotTest).run, config)