From c0613df808b77378c909347e7d6137ffd35c1467 Mon Sep 17 00:00:00 2001
From: Marcin Gorzynski <marcin@gorzynski.me>
Date: Thu, 2 Oct 2025 10:28:33 +0200
Subject: [PATCH] skip: hash validation for block 0 and 1

---
 cmd/ethwalinfo/ethwalinfo.go |  5 +++++
 writer_with_verify_hash.go   | 23 +++++++++++++++++++----
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/cmd/ethwalinfo/ethwalinfo.go b/cmd/ethwalinfo/ethwalinfo.go
index 8bb7dd6..3b78777 100644
--- a/cmd/ethwalinfo/ethwalinfo.go
+++ b/cmd/ethwalinfo/ethwalinfo.go
@@ -4,6 +4,7 @@ import (
 	"cmp"
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/0xsequence/ethwal"
 	"github.com/0xsequence/ethwal/storage"
@@ -49,6 +50,8 @@ func main() {
 			var fs storage.FS = local.NewLocalFS("./")
 			if bucket := c.String(GoogleCloudBucket.Name); bucket != "" {
 				fs = gcloud.NewGCloudFS(bucket, nil)
+			} else if strings.HasPrefix(c.String(DatasetPathFlag.Name), "/") {
+				fs = local.NewLocalFS("/")
 			}
 
 			dataset := ethwal.Dataset{
@@ -91,6 +94,8 @@ func main() {
 					var fs storage.FS = local.NewLocalFS("./")
 					if bucket := c.String(GoogleCloudBucket.Name); bucket != "" {
 						fs = gcloud.NewGCloudFS(bucket, nil)
+					} else if strings.HasPrefix(c.String(DatasetPathFlag.Name), "/") {
+						fs = local.NewLocalFS("/")
 					}
 
 					dataset := ethwal.Dataset{
diff --git a/writer_with_verify_hash.go b/writer_with_verify_hash.go
index 4f93493..76a9bcc 100644
--- a/writer_with_verify_hash.go
+++ b/writer_with_verify_hash.go
@@ -45,26 +45,41 @@ func NewWriterWithVerifyHash[T any](writer Writer[T], blockHashGetter BlockHashG
 }
 
 func (w *writerWithVerifyHash[T]) Write(ctx context.Context, b Block[T]) error {
-	var err error
-	if w.prevHash == (common.Hash{}) && b.Number > 1 {
-		w.prevHash, err = w.blockHashGetter(ctx, b.Number-1)
+	// Skip validation if block is first block
+	if b.Number == 1 {
+		if err := w.Writer.Write(ctx, b); err != nil {
+			return fmt.Errorf("failed to write block: %w", err)
+		}
+
+		w.prevHash = b.Hash
+		return nil
+	}
+
+	// Get previous hash if not already set
+	if w.prevHash == (common.Hash{}) {
+		prevHash, err := w.blockHashGetter(ctx, b.Number-1)
 		if err != nil {
 			return fmt.Errorf("failed to get block hash: %w", err)
 		}
+
+		w.prevHash = prevHash
 	}
 
+	// Validate parent hash
 	if b.Parent != w.prevHash {
 		w.prevHash = common.Hash{}
 		return fmt.Errorf("parent hash mismatch, expected %s, got %s",
 			w.prevHash.String(), b.Parent.String())
 	}
 
-	err = w.Writer.Write(ctx, b)
+	// Write block
+	err := w.Writer.Write(ctx, b)
 	if err != nil {
 		w.prevHash = common.Hash{}
 		return fmt.Errorf("failed to write block: %w", err)
 	}
 
+	// Update prev hash
 	w.prevHash = b.Hash
 	return nil
 }