From a95948bcd6e7457fb12aa8f0d112db48e9ad7707 Mon Sep 17 00:00:00 2001
From: Roy Crihfield <roy@manteia.ltd>
Date: Wed, 17 Apr 2024 22:08:34 +0800
Subject: [PATCH] allow zero state root

---
 trie_by_cid/trie/trie_reader.go       | 9 ++++-----
 trie_by_cid/triedb/hashdb/database.go | 7 +++++--
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/trie_by_cid/trie/trie_reader.go b/trie_by_cid/trie/trie_reader.go
index 091b0a1..09aa7e7 100644
--- a/trie_by_cid/trie/trie_reader.go
+++ b/trie_by_cid/trie/trie_reader.go
@@ -19,7 +19,6 @@ package trie
 import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
-	"github.com/ethereum/go-ethereum/log"
 
 	"github.com/cerc-io/ipld-eth-statedb/trie_by_cid/trie/triestate"
 	"github.com/cerc-io/ipld-eth-statedb/trie_by_cid/triedb/database"
@@ -35,12 +34,12 @@ type trieReader struct {
 
 // newTrieReader initializes the trie reader with the given node reader.
 func newTrieReader(stateRoot, owner common.Hash, db database.Database) (*trieReader, error) {
-	if stateRoot == (common.Hash{}) || stateRoot == types.EmptyRootHash {
-		if stateRoot == (common.Hash{}) {
-			log.Error("Zero state root hash!")
-		}
+	if stateRoot == types.EmptyRootHash {
 		return &trieReader{owner: owner}, nil
 	}
+	// Originally, passing a zero state root also caused the reader to not be set
+	// We allow it for storage tries for simplicity (ipld-eth-statedb change)
+
 	reader, err := db.Reader(stateRoot)
 	if err != nil {
 		return nil, &MissingNodeError{Owner: owner, NodeHash: stateRoot, err: err}
diff --git a/trie_by_cid/triedb/hashdb/database.go b/trie_by_cid/triedb/hashdb/database.go
index bd3a191..68f539f 100644
--- a/trie_by_cid/triedb/hashdb/database.go
+++ b/trie_by_cid/triedb/hashdb/database.go
@@ -641,8 +641,11 @@ func (db *Database) Scheme() string {
 // Reader retrieves a node reader belonging to the given state root.
 // An error will be returned if the requested state is not available.
 func (db *Database) Reader(root common.Hash) (*reader, error) {
-	if _, err := db.node(root, internal.StateTrieCodec); err != nil {
-		return nil, fmt.Errorf("state %#x is not available, %v", root, err)
+	// (ipld-eth-statedb change) Allow zero state roots for storage tries
+	if root != (common.Hash{}) {
+		if _, err := db.node(root, internal.StateTrieCodec); err != nil {
+			return nil, fmt.Errorf("state %#x is not available, %v", root, err)
+		}
 	}
 	return &reader{db: db}, nil
 }