feat(backend): add GetFileMd5 function for calculating MD5 hash of files to enhance file integrity verification

backend/internal/utils/file.go

@@ -1,7 +1,33 @@
 package utils
 
-import "fmt"
+import (
+	"bufio"
+	"crypto/md5"
+	"fmt"
+	"io"
+	"os"
+)
 
 func GetFileId(fileHash string, fileSize int64) string {
 	return fmt.Sprintf("%s_%d", fileHash, fileSize)
 }
+
+func GetFileMd5(file *os.File) (string, error) {
+
+	const bufferSize = 1024 * 1000 // 1MB
+
+	hash := md5.New()
+	for buf, reader := make([]byte, bufferSize), bufio.NewReader(file); ; {
+		n, err := reader.Read(buf)
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return "", err
+		}
+
+		hash.Write(buf[:n])
+	}
+
+	return fmt.Sprintf("%x", hash.Sum(nil)), nil
+}