Maint: port forwarding refactoring (#543)

- portforward package
- portforward run loop
- Less functional arguments and cycles

internal/portforward/fs.go

@@ -0,0 +1,37 @@
+package portforward
+
+import (
+	"fmt"
+	"os"
+)
+
+func (l *Loop) removePortForwardedFile() {
+	filepath := l.state.GetSettings().Filepath
+	l.logger.Info("removing port file " + filepath)
+	if err := os.Remove(filepath); err != nil {
+		l.logger.Error(err.Error())
+	}
+}
+
+func (l *Loop) writePortForwardedFile(port uint16) {
+	filepath := l.state.GetSettings().Filepath
+	l.logger.Info("writing port file " + filepath)
+	if err := writePortForwardedToFile(filepath, port); err != nil {
+		l.logger.Error(err.Error())
+	}
+}
+
+func writePortForwardedToFile(filepath string, port uint16) (err error) {
+	file, err := os.OpenFile(filepath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+
+	_, err = file.Write([]byte(fmt.Sprint(port)))
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+
+	return file.Close()
+}