From 1ca5dc8496c67dcffd144b1071c5c045733a5461 Mon Sep 17 00:00:00 2001
From: Pavel Vymetálek <pavel@vym.cz>
Date: Mon, 2 Nov 2026 09:26:46 +0100
Subject: Cleaner serial port initialization, detection of serial device
 disconnection

---
 sercp.c | 66 ++++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/sercp.c b/sercp.c
index 7acda1e..5eb087f 100644
--- a/sercp.c
+++ b/sercp.c
@@ -366,6 +366,14 @@ static void SignalHandler(int sig) {
 	exit(EXIT_FAILURE);
 }
 
+//*****************************************************************************
+
+void SerialDeviceError(void) {
+	CloseSerialPort();
+	fprintf(stderr, "\n[ERROR] The device %s has been disconnected or is invalid!\n", SERIALDEVICE);
+	exit(-1);
+}
+
 //*****************************************************************************
 //
 
@@ -583,6 +591,10 @@ uint8_t WaitReadAck(void) {
 	memset(buf_ack, 0, 8);
 	while (1) {
 		result = poll (spolfd_serial, 1, 300);		// 200ms timeout
+		if (spolfd_serial->revents & (POLLHUP | POLLERR | POLLNVAL)) {
+			SerialDeviceError();
+			break;
+		}
 		if (result == 0) {
 			// nothing is comming
 			continue;
@@ -671,6 +683,11 @@ void sercpRecv(void) {
 	while (is_continue) {
 #ifndef _WIN32
 		result = poll (spolfd_serial, 1, 200);		// 200ms timeout
+		if (spolfd_serial->revents & (POLLHUP | POLLERR | POLLNVAL)) {
+			SerialDeviceError();
+			break;
+		}
+
 		if (result == 0) {
 			// nothing is comming
 			continue;
@@ -988,6 +1005,7 @@ int OpenUart() {
 	return (0);
 #else
 	struct termios oldtio, newtio;
+	speed_t serial_speed;
 	/* open the device to be non-blocking (read will return immediatly) */
 	serial_fd = open(SERIALDEVICE, O_RDWR | O_NOCTTY | O_NONBLOCK);	 	//	| O_NDELAY
 	if (serial_fd < 0) {
@@ -1016,61 +1034,59 @@ int OpenUart() {
 	tcgetattr(serial_fd, &oldtio); /* save current port settings */
 	memset(&newtio, 0, sizeof (newtio));
 	switch (baud_rate){
+#ifdef B921600
 		case 921600:
-			newtio.c_cflag = B921600;
+			serial_speed = B921600;
 			break;
+#endif
+#ifdef B460800
 		case 460800:
-			newtio.c_cflag = B460800;
+			serial_speed = B460800;
 			break;
+#endif
 		case 230400:
-			newtio.c_cflag = B230400;
+			serial_speed = B230400;
 			break;
 		case 115200:
-			newtio.c_cflag = B115200;
+			serial_speed = B115200;
 			break;
 		case 57600:
-			newtio.c_cflag = B57600;
+			serial_speed = B57600;
 			break;
 		case 38400:
-			newtio.c_cflag = B38400;
+			serial_speed = B38400;
 			break;
 		case 19200:
-			newtio.c_cflag = B19200;
+			serial_speed = B19200;
 			break;
 		case 9600:
-			newtio.c_cflag = B9600;
+			serial_speed = B9600;
 			break;
 		case 4800:
-			newtio.c_cflag = B4800;
+			serial_speed = B4800;
 			break;
 		case 2400:
-			newtio.c_cflag = B2400;
+			serial_speed = B2400;
 			break;
 		case 1200:
-			newtio.c_cflag = B1200;
+			serial_speed = B1200;
 			break;
 		default:
 			baud_rate = 38400;
-			newtio.c_cflag = B38400;
+			serial_speed = B38400;
 			break;
 	}
-	cfsetospeed(&newtio, baud_rate);
-	cfsetispeed(&newtio, baud_rate);		// set ispeed same as ospeed (see POSIX)
+	newtio.c_cflag = CS8 | CLOCAL | CREAD;
+	if (is_flow_control_hw) {
 #if defined (__APPLE__) || defined (BSD)
-	if (is_flow_control_none) {
-		printf("Sorry, flow control is not tested on this platform\n");
-		newtio.c_cflag |= CS8 | CLOCAL | CREAD | HUPCL;
-	} else {
-		newtio.c_cflag |= CS8 | CLOCAL | CREAD | CCTS_OFLOW | CRTS_IFLOW | HUPCL;
-	}
+		newtio.c_cflag |= CCTS_OFLOW | CRTS_IFLOW;
 #else
-	if (is_flow_control_hw) {
 		// standard CTS/RTS flow control for old .sercp protocol
-		newtio.c_cflag |= CS8 | CLOCAL | CREAD | CRTSCTS;
-	} else {
-		newtio.c_cflag |= CS8 | CLOCAL | CREAD;
-	}
+		newtio.c_cflag |= CRTSCTS;
 #endif
+	}
+	cfsetospeed(&newtio, serial_speed);
+	cfsetispeed(&newtio, serial_speed);		// set ispeed same as ospeed (see POSIX)
 	newtio.c_iflag &= ~(IXON | IXOFF | IXANY);
 	newtio.c_oflag &= ~(OPOST);
 	newtio.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);		// raw input
-- 
cgit