From 0fde3f8b48918b46b899f7236fd234cca728a1a4 Mon Sep 17 00:00:00 2001
From: Aaron Buchwald <aaron.buchwald56@gmail.com>
Date: Fri, 22 Oct 2021 18:32:10 -0400
Subject: [PATCH] Add simple helper for writing/reading blocks from file

---
 core/types/block.go      | 33 ++++++++++++++++++++++++++++
 core/types/block_test.go | 46 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/core/types/block.go b/core/types/block.go
index 360f1eb47c2bc..839eb71cecba4 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -21,7 +21,9 @@ import (
 	"encoding/binary"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"math/big"
+	"os"
 	"reflect"
 	"sync/atomic"
 	"time"
@@ -383,3 +385,34 @@ func (b *Block) Hash() common.Hash {
 }
 
 type Blocks []*Block
+
+func WriteBlocks(w io.Writer, blocks Blocks) error {
+	return rlp.Encode(w, blocks)
+}
+
+func ReadBlocks(b []byte) ([]*Block, error) {
+	blocks := new(Blocks)
+	if err := rlp.DecodeBytes(b, blocks); err != nil {
+		return nil, err
+	}
+	return *blocks, nil
+}
+
+func WriteBlocksToFile(filename string, blocks Blocks) error {
+	f, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	return WriteBlocks(f, blocks)
+}
+
+func ReadBlocksFromFile(filename string) ([]*Block, error) {
+	b, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	return ReadBlocks(b)
+}
diff --git a/core/types/block_test.go b/core/types/block_test.go
index 0b9a4def8d287..8b412b242753a 100644
--- a/core/types/block_test.go
+++ b/core/types/block_test.go
@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"hash"
 	"math/big"
+	"path"
 	"reflect"
 	"testing"
 
@@ -217,6 +218,51 @@ func BenchmarkEncodeBlock(b *testing.B) {
 	}
 }
 
+func TestEncodeBlocks(t *testing.T) {
+	blocks := []*Block{
+		makeBenchBlock(),
+		makeBenchBlock(),
+		makeBenchBlock(),
+	}
+
+	buffer := bytes.NewBuffer(make([]byte, 0, 32000))
+	if err := WriteBlocks(buffer, blocks); err != nil {
+		t.Fatal(err)
+	}
+
+	decodedBlocks, err := ReadBlocks(buffer.Bytes())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(blocks) != len(decodedBlocks) {
+		t.Fatalf("expected decoded blocks (%d) == blocks (%d)", len(decodedBlocks), len(blocks))
+	}
+	for i, decodedBlock := range decodedBlocks {
+		if blocks[i].Hash() != decodedBlock.Hash() {
+			t.Fatalf("Expected hatches to match at index %d, found decoded block hash: %s, actual hash: %s", i, decodedBlock.Hash(), blocks[i].Hash())
+		}
+	}
+
+	tempFile := path.Join(t.TempDir(), "blocks")
+	if err := WriteBlocksToFile(tempFile, blocks); err != nil {
+		t.Fatal(err)
+	}
+
+	blocksFromFile, err := ReadBlocksFromFile(tempFile)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(blocks) != len(blocksFromFile) {
+		t.Fatalf("expected blocks from file (%d) == blocks (%d)", len(blocksFromFile), len(blocks))
+	}
+	for i, blockFromFile := range blocksFromFile {
+		if blocks[i].Hash() != blockFromFile.Hash() {
+			t.Fatalf("Expected hatches to match at index %d, found block from file hash: %s, actual hash: %s", i, blockFromFile.Hash(), blocks[i].Hash())
+		}
+	}
+}
+
 // testHasher is the helper tool for transaction/receipt list hashing.
 // The original hasher is trie, in order to get rid of import cycle,
 // use the testing hasher instead.