X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=serialport.c;h=1b5a95e21d87fdfe48c7c10d686a47e2acac0e24;hb=HEAD;hp=72010913ae4e7a2cc4772112afc857350e7a37f0;hpb=d81a4dfdc6f9779c13c6dd10b342e9d4c5a7ff97;p=libserialport.git

diff --git a/serialport.c b/serialport.c
index 7201091..1b5a95e 100644
--- a/serialport.c
+++ b/serialport.c
@@ -155,10 +155,7 @@ SP_API enum sp_transport sp_get_port_transport(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
-	if (!port)
-		RETURN_ERROR(SP_ERR_ARG, "Null port");
-
-	RETURN_INT(port->transport);
+	RETURN_INT(port ? port->transport : SP_TRANSPORT_NATIVE);
 }
 
 SP_API enum sp_return sp_get_port_usb_bus_address(const struct sp_port *port,
@@ -551,6 +548,39 @@ SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
 	if ((port->fd = open(port->name, flags_local)) < 0)
 		RETURN_FAIL("open() failed");
+
+	/*
+	 * On POSIX in the default case the file descriptor of a serial port
+	 * is not opened exclusively. Therefore the settings of a port are
+	 * overwritten if the serial port is opened a second time. Windows
+	 * opens all serial ports exclusively.
+	 * So the idea is to open the serial ports alike in the exclusive mode.
+	 *
+	 * ioctl(*, TIOCEXCL) defines the file descriptor as exclusive. So all
+	 * further open calls on the serial port will fail.
+	 *
+	 * There is a race condition if two processes open the same serial
+	 * port. None of the processes will notice the exclusive ownership of
+	 * the other process because ioctl() doesn't return an error code if
+	 * the file descriptor is already marked as exclusive.
+	 * This can be solved with flock(). It returns an error if the file
+	 * descriptor is already locked by another process.
+	 */
+#ifdef HAVE_FLOCK
+	if (flock(port->fd, LOCK_EX | LOCK_NB) < 0)
+		RETURN_FAIL("flock() failed");
+#endif
+
+#ifdef TIOCEXCL
+	/*
+	 * Before Linux 3.8 ioctl(*, TIOCEXCL) was not implemented and could
+	 * lead to EINVAL or ENOTTY.
+	 * These errors aren't fatal and can be ignored.
+	 */
+	if (ioctl(port->fd, TIOCEXCL) < 0 && errno != EINVAL && errno != ENOTTY)
+		RETURN_FAIL("ioctl() failed");
+#endif
+
 #endif
 
 	ret = get_config(port, &data, &config);
@@ -560,6 +590,15 @@ SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 		RETURN_CODEVAL(ret);
 	}
 
+	/*
+	 * Assume a default baudrate if the OS does not provide one.
+	 * Cannot assign -1 here since Windows holds the baudrate in
+	 * the DCB and does not configure the rate individually.
+	 */
+	if (config.baudrate == 0) {
+		config.baudrate = 9600;
+	}
+
 	/* Set sane port settings. */
 #ifdef _WIN32
 	data.dcb.fBinary = TRUE;
@@ -603,7 +642,8 @@ SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	data.term.c_cc[VTIME] = 0;
 
 	/* Ignore modem status lines; enable receiver; leave control lines alone on close. */
-	data.term.c_cflag |= (CLOCAL | CREAD | HUPCL);
+	data.term.c_cflag |= (CLOCAL | CREAD);
+	data.term.c_cflag &= ~(HUPCL);
 #endif
 
 #ifdef _WIN32
@@ -846,7 +886,7 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeout timeout;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -1051,7 +1091,7 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeout timeout;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -1174,7 +1214,7 @@ SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
 	size_t bytes_read = 0;
 	struct timeout timeout;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -1648,28 +1688,25 @@ static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 
 	config->bits = data->dcb.ByteSize;
 
-	if (data->dcb.fParity)
-		switch (data->dcb.Parity) {
-		case NOPARITY:
-			config->parity = SP_PARITY_NONE;
-			break;
-		case ODDPARITY:
-			config->parity = SP_PARITY_ODD;
-			break;
-		case EVENPARITY:
-			config->parity = SP_PARITY_EVEN;
-			break;
-		case MARKPARITY:
-			config->parity = SP_PARITY_MARK;
-			break;
-		case SPACEPARITY:
-			config->parity = SP_PARITY_SPACE;
-			break;
-		default:
-			config->parity = -1;
-		}
-	else
+	switch (data->dcb.Parity) {
+	case NOPARITY:
 		config->parity = SP_PARITY_NONE;
+		break;
+	case ODDPARITY:
+		config->parity = SP_PARITY_ODD;
+		break;
+	case EVENPARITY:
+		config->parity = SP_PARITY_EVEN;
+		break;
+	case MARKPARITY:
+		config->parity = SP_PARITY_MARK;
+		break;
+	case SPACEPARITY:
+		config->parity = SP_PARITY_SPACE;
+		break;
+	default:
+		config->parity = -1;
+	}
 
 	switch (data->dcb.StopBits) {
 	case ONESTOPBIT: