UPDATE: Add ldiff

pkg/firefly/chunk.go

@@ -0,0 +1,73 @@
+package firefly
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+
+	"golang.org/x/exp/mmap"
+)
+
+type ChunkInfo struct {
+	Name   string
+	Offset int64
+	Size   int64
+}
+
+func ProcessWithBufReader(path string, chunks []ChunkInfo) {
+	file, err := os.Open(path)
+	if err != nil {
+		fmt.Printf("Error opening file %s: %v\n", path, err)
+		return
+	}
+	defer file.Close()
+
+	for _, chunk := range chunks {
+		buffer, err := ReadChunkData(file, chunk.Offset, chunk.Size)
+		if err != nil {
+			fmt.Printf("Error reading chunk %s: %v\n", chunk.Name, err)
+			continue
+		}
+
+		assetPath := filepath.Join("chunk_tmp", chunk.Name)
+		parentDir := filepath.Dir(assetPath)
+		if _, err := os.Stat(parentDir); os.IsNotExist(err) {
+			if err := os.MkdirAll(parentDir, 0o755); err != nil {
+				fmt.Printf("Error creating directory %s: %v\n", parentDir, err)
+				continue
+			}
+		}
+
+		if err := os.WriteFile(assetPath, buffer, 0o644); err != nil {
+			fmt.Printf("Error writing chunk file %s: %v\n", assetPath, err)
+		}
+	}
+}
+
+func ReadChunkData(file *os.File, offset, size int64) ([]byte, error) {
+	info, err := file.Stat()
+	if err != nil {
+		return nil, fmt.Errorf("error getting file info: %w", err)
+	}
+
+	if info.Size() > 1024*1024 && size > 1024*1024 {
+		mmapReader, err := mmap.Open(file.Name())
+		if err == nil {
+			defer mmapReader.Close()
+			buffer := make([]byte, size)
+			_, err := mmapReader.ReadAt(buffer, offset)
+			if err != nil && err != io.EOF {
+				return nil, fmt.Errorf("error reading mmap: %w", err)
+			}
+			return buffer, nil
+		}
+	}
+
+	buffer := make([]byte, size)
+	_, err = file.ReadAt(buffer, offset)
+	if err != nil && err != io.EOF {
+		return nil, fmt.Errorf("error reading buffered: %w", err)
+	}
+	return buffer, nil
+}