platform: Add group interface

experimental/libbox/command_shared.go

@@ -0,0 +1,39 @@
+package libbox
+
+import (
+	"encoding/binary"
+	"io"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/rw"
+)
+
+func readError(reader io.Reader) error {
+	var hasError bool
+	err := binary.Read(reader, binary.BigEndian, &hasError)
+	if err != nil {
+		return err
+	}
+	if hasError {
+		errorMessage, err := rw.ReadVString(reader)
+		if err != nil {
+			return err
+		}
+		return E.New(errorMessage)
+	}
+	return nil
+}
+
+func writeError(writer io.Writer, wErr error) error {
+	err := binary.Write(writer, binary.BigEndian, wErr != nil)
+	if err != nil {
+		return err
+	}
+	if wErr != nil {
+		err = rw.WriteVString(writer, wErr.Error())
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}