Improved error reporting for parity settings

serial.go

@@ -94,6 +94,8 @@ const (
 	InvalidSpeed
 	// InvalidDataBits the number of data bits is not valid or not supported
 	InvalidDataBits
+	// InvalidParity the selected parity is not valid or not supported
+	InvalidParity
 	// ErrorEnumeratingPorts an error occurred while listing serial port
 	ErrorEnumeratingPorts
 )
@@ -113,6 +115,8 @@ func (e PortError) EncodedErrorString() string {
 		return "Invalid port speed"
 	case InvalidDataBits:
 		return "Invalid port data bits"
+	case InvalidParity:
+		return "Port parity invalid or not supported"
 	case ErrorEnumeratingPorts:
 		return "Could not enumerate serial ports"
 	default:

serial_unix.go

@@ -176,15 +176,23 @@ func setTermSettingsParity(parity Parity, settings *syscall.Termios) error {
 		settings.Cflag &^= tcCMSPAR
 		settings.Iflag |= syscall.INPCK
 	case MarkParity:
+		if tcCMSPAR == 0 {
+			return &PortError{code: InvalidParity}
+		}
 		settings.Cflag |= syscall.PARENB
 		settings.Cflag |= syscall.PARODD
 		settings.Cflag |= tcCMSPAR
 		settings.Iflag |= syscall.INPCK
 	case SpaceParity:
+		if tcCMSPAR == 0 {
+			return &PortError{code: InvalidParity}
+		}
 		settings.Cflag |= syscall.PARENB
 		settings.Cflag &^= syscall.PARODD
 		settings.Cflag |= tcCMSPAR
 		settings.Iflag |= syscall.INPCK
+	default:
+		return &PortError{code: InvalidParity}
 	}
 	return nil
 }