Move file handling to backend/files.go

cmd/backend/files.go

@@ -0,0 +1,28 @@
+package backend
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+func CopyFile(src, dst string) error {
+	srcFile, err := os.Open(src)
+	if err != nil {
+		return fmt.Errorf("error opening source file: %v", err)
+	}
+	defer srcFile.Close()
+
+	dstFile, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
+	if err != nil {
+		return fmt.Errorf("error opening destination file: %v", err)
+	}
+	defer dstFile.Close()
+
+	_, err = io.Copy(dstFile, srcFile)
+	if err != nil {
+		return fmt.Errorf("error copying file: %v", err)
+	}
+
+	return dstFile.Sync()
+}