X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=serialport.c;h=1b5a95e21d87fdfe48c7c10d686a47e2acac0e24;hb=HEAD;hp=bbc6ea69020baa03496e71bc0c935f15b6ff6309;hpb=3317d678de42aa183b88f466bd16459389d74828;p=libserialport.git

diff --git a/serialport.c b/serialport.c
index bbc6ea6..1b5a95e 100644
--- a/serialport.c
+++ b/serialport.c
@@ -21,8 +21,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <config.h>
-#include "libserialport.h"
 #include "libserialport_internal.h"
 
 static const struct std_baudrate std_baudrates[] = {
@@ -55,176 +53,13 @@ static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	const struct sp_port_config *config);
 
-/* Timing abstraction */
-
-struct time {
-#ifdef _WIN32
-	int64_t ticks;
-#else
-	struct timeval tv;
-#endif
-};
-
-struct timeout {
-	unsigned int ms, limit_ms;
-	struct time start, now, end, delta, delta_max;
-	struct timeval delta_tv;
-	bool overflow;
-};
-
-static void time_get(struct time *time)
-{
-#ifdef _WIN32
-	LARGE_INTEGER count;
-	QueryPerformanceCounter(&count);
-	time->ticks = count.QuadPart;
-#elif defined(HAVE_CLOCK_GETTIME)
-	struct timespec ts;
-	if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
-		clock_gettime(CLOCK_REALTIME, &ts);
-	time->tv.tv_sec = ts.tv_sec;
-	time->tv.tv_usec = ts.tv_nsec / 1000;
-#elif defined(__APPLE__)
-	mach_timebase_info_data_t info;
-	mach_timebase_info(&info);
-	uint64_t ticks = mach_absolute_time();
-	uint64_t ns = (ticks * info.numer) / info.denom;
-	time->tv.tv_sec = ns / 1000000000;
-	time->tv.tv_usec = (ns % 1000000000) / 1000;
-#else
-	gettimeofday(&time->tv, NULL);
-#endif
-}
-
-static void time_set_ms(struct time *time, unsigned int ms)
-{
-#ifdef _WIN32
-	LARGE_INTEGER frequency;
-	QueryPerformanceFrequency(&frequency);
-	time->ticks = ms * (frequency.QuadPart / 1000);
-#else
-	time->tv.tv_sec = ms / 1000;
-	time->tv.tv_usec = (ms % 1000) * 1000;
-#endif
-}
-
-static void time_add(const struct time *a,
-		const struct time *b, struct time *result)
-{
-#ifdef _WIN32
-	result->ticks = a->ticks + b->ticks;
-#else
-	timeradd(&a->tv, &b->tv, &result->tv);
-#endif
-}
-
-static void time_sub(const struct time *a,
-		const struct time *b, struct time *result)
-{
-#ifdef _WIN32
-	result->ticks = a->ticks - b->ticks;
-#else
-	timersub(&a->tv, &b->tv, &result->tv);
-#endif
-}
-
-static bool time_greater(const struct time *a, const struct time *b)
-{
-#ifdef _WIN32
-	return (a->ticks > b->ticks);
-#else
-	return timercmp(&a->tv, &b->tv, >);
-#endif
-}
-
-static void time_as_timeval(const struct time *time, struct timeval *tv)
-{
-#ifdef _WIN32
-	LARGE_INTEGER frequency;
-	QueryPerformanceFrequency(&frequency);
-	tv->tv_sec = time->ticks / frequency.QuadPart;
-	tv->tv_usec = (time->ticks % frequency.QuadPart) /
-		(frequency.QuadPart / 1000000);
-#else
-	*tv = time->tv;
-#endif
-}
-
-static unsigned int time_as_ms(const struct time *time)
-{
-#ifdef _WIN32
-	LARGE_INTEGER frequency;
-	QueryPerformanceFrequency(&frequency);
-	return time->ticks / (frequency.QuadPart / 1000);
-#else
-	return time->tv.tv_sec * 1000 + time->tv.tv_usec / 1000;
-#endif
-}
-
-static void timeout_start(struct timeout *timeout, unsigned int timeout_ms)
-{
-	timeout->ms = timeout_ms;
-
-	/* Get time at start of operation. */
-	time_get(&timeout->start);
-	/* Define duration of timeout. */
-	time_set_ms(&timeout->delta, timeout_ms);
-	/* Calculate time at which we should give up. */
-	time_add(&timeout->start, &timeout->delta, &timeout->end);
-	/* Disable limit unless timeout_limit() called. */
-	timeout->limit_ms = 0;
-}
-
-static void timeout_limit(struct timeout *timeout, unsigned int limit_ms)
-{
-	timeout->limit_ms = limit_ms;
-	timeout->overflow = (timeout->ms > timeout->limit_ms);
-	time_set_ms(&timeout->delta_max, timeout->limit_ms);
-}
-
-static bool timeout_check(struct timeout *timeout)
-{
-	if (timeout->ms == 0)
-		return false;
-
-	time_get(&timeout->now);
-	time_sub(&timeout->end, &timeout->now, &timeout->delta);
-	if (timeout->limit_ms)
-		if ((timeout->overflow = time_greater(&timeout->delta, &timeout->delta_max)))
-			timeout->delta = timeout->delta_max;
-
-	return time_greater(&timeout->now, &timeout->end);
-}
-
-#ifndef _WIN32
-static struct timeval *timeout_timeval(struct timeout *timeout)
-{
-	if (timeout->ms == 0)
-		return NULL;
-
-	time_as_timeval(&timeout->delta, &timeout->delta_tv);
-
-	return &timeout->delta_tv;
-}
-#endif
-
-static unsigned int timeout_remaining_ms(struct timeout *timeout)
-{
-	if (timeout->ms == 0)
-		return -1;
-	else if (timeout->limit_ms && timeout->overflow)
-		return timeout->limit_ms;
-	else
-		return time_as_ms(&timeout->delta);
-}
-
 SP_API enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
 {
 	struct sp_port *port;
 #ifndef NO_PORT_METADATA
 	enum sp_return ret;
 #endif
-	int len;
+	size_t len;
 
 	TRACE("%s, %p", portname, port_ptr);
 
@@ -320,10 +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,
@@ -488,7 +320,7 @@ SP_PRIV struct sp_port **list_append(struct sp_port **list,
                                      const char *portname)
 {
 	void *tmp;
-	unsigned int count;
+	size_t count;
 
 	for (count = 0; list[count]; count++)
 		;
@@ -653,7 +485,7 @@ SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	if (flags & SP_MODE_WRITE)
 		desired_access |= GENERIC_WRITE;
 
-	port->hdl = CreateFile(escaped_port_name, desired_access, 0, 0,
+	port->hdl = CreateFileA(escaped_port_name, desired_access, 0, 0,
 			 OPEN_EXISTING, flags_and_attributes, 0);
 
 	free(escaped_port_name);
@@ -716,6 +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);
@@ -725,6 +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;
@@ -768,7 +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
@@ -947,47 +822,71 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
 		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD bytes_written = 0;
+	DWORD remaining_ms, write_size, bytes_written;
+	size_t remaining_bytes, total_bytes_written = 0;
+	const uint8_t *write_ptr = (uint8_t *) buf;
+	bool result;
+	struct timeout timeout;
+
+	timeout_start(&timeout, timeout_ms);
 
 	TRY(await_write_completion(port));
 
-	/* Set timeout. */
-	if (port->timeouts.WriteTotalTimeoutConstant != timeout_ms) {
-		port->timeouts.WriteTotalTimeoutConstant = timeout_ms;
-		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-			RETURN_FAIL("SetCommTimeouts() failed");
-	}
+	while (total_bytes_written < count) {
 
-	/* Reduce count if it exceeds the WriteFile limit. */
-	if (count > WRITEFILE_MAX_SIZE)
-		count = WRITEFILE_MAX_SIZE;
+		if (timeout_check(&timeout))
+			break;
 
-	/* Start write. */
-	if (WriteFile(port->hdl, buf, count, NULL, &port->write_ovl)) {
-		DEBUG("Write completed immediately");
-		RETURN_INT(count);
-	} else if (GetLastError() == ERROR_IO_PENDING) {
-		DEBUG("Waiting for write to complete");
-		if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0) {
-			if (GetLastError() == ERROR_SEM_TIMEOUT) {
-				DEBUG("Write timed out");
-				RETURN_INT(0);
-			} else {
-				RETURN_FAIL("GetOverlappedResult() failed");
+		remaining_ms = timeout_remaining_ms(&timeout);
+
+		if (port->timeouts.WriteTotalTimeoutConstant != remaining_ms) {
+			port->timeouts.WriteTotalTimeoutConstant = remaining_ms;
+			if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+				RETURN_FAIL("SetCommTimeouts() failed");
+		}
+
+		/* Reduce write size if it exceeds the WriteFile limit. */
+		remaining_bytes = count - total_bytes_written;
+		if (remaining_bytes > WRITEFILE_MAX_SIZE)
+			write_size = WRITEFILE_MAX_SIZE;
+		else
+			write_size = (DWORD) remaining_bytes;
+
+		/* Start write. */
+
+		result = WriteFile(port->hdl, write_ptr, write_size, NULL, &port->write_ovl);
+
+		timeout_update(&timeout);
+
+		if (result) {
+			DEBUG("Write completed immediately");
+			bytes_written = write_size;
+		} else if (GetLastError() == ERROR_IO_PENDING) {
+			DEBUG("Waiting for write to complete");
+			if (GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE) == 0) {
+				if (GetLastError() == ERROR_SEM_TIMEOUT) {
+					DEBUG("Write timed out");
+					break;
+				} else {
+					RETURN_FAIL("GetOverlappedResult() failed");
+				}
 			}
+			DEBUG_FMT("Write completed, %d/%d bytes written", bytes_written, write_size);
+		} else {
+			RETURN_FAIL("WriteFile() failed");
 		}
-		DEBUG_FMT("Write completed, %d/%d bytes written", bytes_written, count);
-		RETURN_INT(bytes_written);
-	} else {
-		RETURN_FAIL("WriteFile() failed");
+
+		write_ptr += bytes_written;
+		total_bytes_written += bytes_written;
 	}
+
+	RETURN_INT((int) total_bytes_written);
 #else
 	size_t bytes_written = 0;
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeout timeout;
-	int started = 0;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -996,16 +895,14 @@ SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
 
 	/* Loop until we have written the requested number of bytes. */
 	while (bytes_written < count) {
-		/*
-		 * Check timeout only if we have run select() at least once,
-		 * to avoid any issues if a short timeout is reached before
-		 * select() is even run.
-		 */
-		if (started && timeout_check(&timeout))
+
+		if (timeout_check(&timeout))
 			break;
 
 		result = select(port->fd + 1, NULL, &fds, NULL, timeout_timeval(&timeout));
-		started = 1;
+
+		timeout_update(&timeout);
+
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -1057,7 +954,7 @@ SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
 		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD buf_bytes;
+	size_t buf_bytes;
 
 	/* Check whether previous write is complete. */
 	if (port->writing) {
@@ -1087,7 +984,7 @@ SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
 	memcpy(port->write_buf, buf, buf_bytes);
 
 	/* Start asynchronous write. */
-	if (WriteFile(port->hdl, port->write_buf, buf_bytes, NULL, &port->write_ovl) == 0) {
+	if (WriteFile(port->hdl, port->write_buf, (DWORD) buf_bytes, NULL, &port->write_ovl) == 0) {
 		if (GetLastError() == ERROR_IO_PENDING) {
 			if ((port->writing = !HasOverlappedIoCompleted(&port->write_ovl)))
 				DEBUG("Asynchronous write completed immediately");
@@ -1101,7 +998,7 @@ SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
 
 	DEBUG("All bytes written immediately");
 
-	RETURN_INT(buf_bytes);
+	RETURN_INT((int) buf_bytes);
 #else
 	/* Returns the number of bytes written, or -1 upon failure. */
 	ssize_t written = write(port->fd, buf, count);
@@ -1159,7 +1056,7 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD bytes_read = 0;
+	DWORD bytes_read;
 
 	/* Set timeout. */
 	if (port->timeouts.ReadIntervalTimeout != 0 ||
@@ -1173,9 +1070,9 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 	}
 
 	/* Start read. */
-	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl)) {
+	if (ReadFile(port->hdl, buf, (DWORD) count, NULL, &port->read_ovl)) {
 		DEBUG("Read completed immediately");
-		bytes_read = count;
+		bytes_read = (DWORD) count;
 	} else if (GetLastError() == ERROR_IO_PENDING) {
 		DEBUG("Waiting for read to complete");
 		if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
@@ -1187,15 +1084,14 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 
 	TRY(restart_wait_if_needed(port, bytes_read));
 
-	RETURN_INT(bytes_read);
+	RETURN_INT((int) bytes_read);
 
 #else
 	size_t bytes_read = 0;
 	unsigned char *ptr = (unsigned char *) buf;
 	struct timeout timeout;
-	int started = 0;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -1204,17 +1100,15 @@ SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
 
 	/* Loop until we have the requested number of bytes. */
 	while (bytes_read < count) {
-		/*
-		 * Check timeout only if we have run select() at least once,
-		 * to avoid any issues if a short timeout is reached before
-		 * select() is even run.
-		 */
-		if (started && timeout_check(&timeout))
+
+		if (timeout_check(&timeout))
 			/* Timeout has expired. */
 			break;
 
 		result = select(port->fd + 1, &fds, NULL, NULL, timeout_timeval(&timeout));
-		started = 1;
+
+		timeout_update(&timeout);
+
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -1293,7 +1187,7 @@ SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
 	/* Loop until we have at least one byte, or timeout is reached. */
 	while (bytes_read == 0) {
 		/* Start read. */
-		if (ReadFile(port->hdl, buf, count, &bytes_read, &port->read_ovl)) {
+		if (ReadFile(port->hdl, buf, (DWORD) count, &bytes_read, &port->read_ovl)) {
 			DEBUG("Read completed immediately");
 		} else if (GetLastError() == ERROR_IO_PENDING) {
 			DEBUG("Waiting for read to complete");
@@ -1319,9 +1213,8 @@ SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
 #else
 	size_t bytes_read = 0;
 	struct timeout timeout;
-	int started = 0;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
 	timeout_start(&timeout, timeout_ms);
 
@@ -1330,17 +1223,15 @@ SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
 
 	/* Loop until we have at least one byte, or timeout is reached. */
 	while (bytes_read == 0) {
-		/*
-		 * Check timeout only if we have run select() at least once,
-		 * to avoid any issues if a short timeout is reached before
-		 * select() is even run.
-		 */
-		if (started && timeout_check(&timeout))
+
+		if (timeout_check(&timeout))
 			/* Timeout has expired. */
 			break;
 
 		result = select(port->fd + 1, &fds, NULL, NULL, timeout_timeval(&timeout));
-		started = 1;
+
+		timeout_update(&timeout);
+
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -1402,7 +1293,7 @@ SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
 	}
 
 	/* Do read. */
-	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0)
+	if (ReadFile(port->hdl, buf, (DWORD) count, NULL, &port->read_ovl) == 0)
 		if (GetLastError() != ERROR_IO_PENDING)
 			RETURN_FAIL("ReadFile() failed");
 
@@ -1456,6 +1347,11 @@ SP_API enum sp_return sp_output_waiting(struct sp_port *port)
 {
 	TRACE("%p", port);
 
+#ifdef __CYGWIN__
+	/* TIOCOUTQ is not defined in Cygwin headers */
+	RETURN_ERROR(SP_ERR_SUPP,
+			"Getting output bytes waiting is not supported on Cygwin");
+#else
 	CHECK_OPEN_PORT();
 
 	DEBUG_FMT("Checking output bytes waiting on port %s", port->name);
@@ -1473,6 +1369,7 @@ SP_API enum sp_return sp_output_waiting(struct sp_port *port)
 		RETURN_FAIL("TIOCOUTQ ioctl failed");
 	RETURN_INT(bytes_waiting);
 #endif
+#endif
 }
 
 SP_API enum sp_return sp_new_event_set(struct sp_event_set **result_ptr)
@@ -1591,7 +1488,8 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
 	RETURN_OK();
 #else
 	struct timeout timeout;
-	int started = 0, result;
+	int poll_timeout;
+	int result;
 	struct pollfd *pollfds;
 	unsigned int i;
 
@@ -1615,18 +1513,19 @@ SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
 
 	/* Loop until an event occurs. */
 	while (1) {
-		/*
-		 * Check timeout only if we have run poll() at least once,
-		 * to avoid any issues if a short timeout is reached before
-		 * poll() is even run.
-		 */
-		if (started && timeout_check(&timeout)) {
+
+		if (timeout_check(&timeout)) {
 			DEBUG("Wait timed out");
 			break;
 		}
 
-		result = poll(pollfds, event_set->count, timeout_remaining_ms(&timeout));
-		started = 1;
+		poll_timeout = (int) timeout_remaining_ms(&timeout);
+		if (poll_timeout == 0)
+			poll_timeout = -1;
+
+		result = poll(pollfds, event_set->count, poll_timeout);
+
+		timeout_update(&timeout);
 
 		if (result < 0) {
 			if (errno == EINTR) {
@@ -1789,28 +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:
@@ -1990,6 +1886,7 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	DEBUG_FMT("Setting configuration for port %s", port->name);
 
 #ifdef _WIN32
+	BYTE* new_buf;
 
 	TRY(await_write_completion(port));
 
@@ -2006,11 +1903,10 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
 		/* Allocate write buffer for 50ms of data at baud rate. */
 		port->write_buf_size = max(config->baudrate / (8 * 20), 1);
-		port->write_buf = realloc(port->write_buf,
-					  port->write_buf_size);
-
-		if (!port->write_buf)
+		new_buf = realloc(port->write_buf, port->write_buf_size);
+		if (!new_buf)
 			RETURN_ERROR(SP_ERR_MEM, "Allocating write buffer failed");
+		port->write_buf = new_buf;
 	}
 
 	if (config->bits >= 0)
@@ -2630,17 +2526,17 @@ SP_API char *sp_last_error_message(void)
 	TRACE_VOID();
 
 #ifdef _WIN32
-	TCHAR *message;
+	char *message;
 	DWORD error = GetLastError();
 
-	DWORD length = FormatMessage(
+	DWORD length = FormatMessageA(
 		FORMAT_MESSAGE_ALLOCATE_BUFFER |
 		FORMAT_MESSAGE_FROM_SYSTEM |
 		FORMAT_MESSAGE_IGNORE_INSERTS,
 		NULL,
 		error,
 		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
-		(LPTSTR) &message,
+		(LPSTR) &message,
 		0, NULL );
 
 	if (length >= 2 && message[length - 2] == '\r')