X-Git-Url: https://sigrok.org/gitweb/?p=libserialport.git;a=blobdiff_plain;f=serialport.c;h=1b71cdbe59eb47ea84520157e0a9ec6998310979;hp=c2946a2f08c427a7a7fe5448989f88dfedefa7cb;hb=HEAD;hpb=da2ede60e441566b074d512ad70b51b5751834ae

diff --git a/serialport.c b/serialport.c
index c2946a2..1b5a95e 100644
--- a/serialport.c
+++ b/serialport.c
@@ -2,9 +2,10 @@
  * This file is part of the libserialport project.
  *
  * Copyright (C) 2010-2012 Bert Vermeulen <bert@biot.com>
- * Copyright (C) 2010-2012 Uwe Hermann <uwe@hermann-uwe.de>
- * Copyright (C) 2013 Martin Ling <martin-libserialport@earth.li>
+ * Copyright (C) 2010-2015 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2013-2015 Martin Ling <martin-libserialport@earth.li>
  * Copyright (C) 2013 Matthias Heidbrink <m-sigrok@heidbrink.biz>
+ * Copyright (C) 2014 Aurelien Jacobs <aurel@gnuage.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as
@@ -20,125 +21,9 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <string.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <errno.h>
-#include <stdio.h>
-#include <stdarg.h>
-#ifdef _WIN32
-#include <windows.h>
-#include <tchar.h>
-#else
-#include <limits.h>
-#include <termios.h>
-#include <sys/ioctl.h>
-#include <sys/time.h>
-#include <limits.h>
-#include <poll.h>
-#endif
-#ifdef __APPLE__
-#include <IOKit/IOKitLib.h>
-#include <IOKit/serial/IOSerialKeys.h>
-#include <IOKit/serial/ioss.h>
-#include <sys/syslimits.h>
-#endif
-#ifdef __linux__
-#ifdef HAVE_LIBUDEV
-#include "libudev.h"
-#endif
-#ifndef __ANDROID__
-#include "linux/serial.h"
-#endif
-#include "linux_termios.h"
-
-/* TCGETX/TCSETX is not available everywhere. */
-#if defined(TCGETX) && defined(TCSETX) && defined(HAVE_TERMIOX)
-#define USE_TERMIOX
-#endif
-#endif
-
-/* TIOCINQ/TIOCOUTQ is not available everywhere. */
-#if !defined(TIOCINQ) && defined(FIONREAD)
-#define TIOCINQ FIONREAD
-#endif
-#if !defined(TIOCOUTQ) && defined(FIONWRITE)
-#define TIOCOUTQ FIONWRITE
-#endif
-
-/* Non-standard baudrates are not available everywhere. */
-#if defined(HAVE_TERMIOS_SPEED) || defined(HAVE_TERMIOS2_SPEED)
-#define USE_TERMIOS_SPEED
-#endif
-
-#include "libserialport.h"
-
-struct sp_port {
-	char *name;
-#ifdef _WIN32
-	HANDLE hdl;
-	COMMTIMEOUTS timeouts;
-	OVERLAPPED write_ovl;
-	OVERLAPPED read_ovl;
-	OVERLAPPED wait_ovl;
-	DWORD events;
-	BYTE pending_byte;
-	BOOL writing;
-#else
-	int fd;
-#endif
-};
-
-struct sp_port_config {
-	int baudrate;
-	int bits;
-	enum sp_parity parity;
-	int stopbits;
-	enum sp_rts rts;
-	enum sp_cts cts;
-	enum sp_dtr dtr;
-	enum sp_dsr dsr;
-	enum sp_xonxoff xon_xoff;
-};
-
-struct port_data {
-#ifdef _WIN32
-	DCB dcb;
-#else
-	struct termios term;
-	int controlbits;
-	int termiox_supported;
-	int rts_flow;
-	int cts_flow;
-	int dtr_flow;
-	int dsr_flow;
-#endif
-};
-
-#ifdef _WIN32
-typedef HANDLE event_handle;
-#else
-typedef int event_handle;
-#endif
+#include "libserialport_internal.h"
 
-/* Standard baud rates. */
-#ifdef _WIN32
-#define BAUD_TYPE DWORD
-#define BAUD(n) {CBR_##n, n}
-#else
-#define BAUD_TYPE speed_t
-#define BAUD(n) {B##n, n}
-#endif
-
-struct std_baudrate {
-	BAUD_TYPE index;
-	int value;
-};
-
-const struct std_baudrate std_baudrates[] = {
+static const struct std_baudrate std_baudrates[] = {
 #ifdef _WIN32
 	/*
 	 * The baudrates 50/75/134/150/200/1800/230400/460800 do not seem to
@@ -158,55 +43,23 @@ const struct std_baudrate std_baudrates[] = {
 #endif
 };
 
-void (*sp_debug_handler)(const char *format, ...) = sp_default_debug_handler;
-
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
 #define NUM_STD_BAUDRATES ARRAY_SIZE(std_baudrates)
 
-/* Debug output macros. */
-#define DEBUG(fmt, ...) do { if (sp_debug_handler) sp_debug_handler(fmt ".\n", ##__VA_ARGS__); } while (0)
-#define DEBUG_ERROR(err, fmt, ...) DEBUG("%s returning " #err ": " fmt, __func__, ##__VA_ARGS__)
-#define DEBUG_FAIL(fmt, ...) do {               \
-	char *errmsg = sp_last_error_message(); \
-	DEBUG("%s returning SP_ERR_FAIL: "fmt": %s", __func__,##__VA_ARGS__,errmsg); \
-	sp_free_error_message(errmsg); \
-} while (0);
-#define RETURN() do { DEBUG("%s returning", __func__); return; } while(0)
-#define RETURN_CODE(x) do { DEBUG("%s returning " #x, __func__); return x; } while (0)
-#define RETURN_CODEVAL(x) do { \
-	switch (x) { \
-		case SP_OK: RETURN_CODE(SP_OK); \
-		case SP_ERR_ARG: RETURN_CODE(SP_ERR_ARG); \
-		case SP_ERR_FAIL: RETURN_CODE(SP_ERR_FAIL); \
-		case SP_ERR_MEM: RETURN_CODE(SP_ERR_MEM); \
-		case SP_ERR_SUPP: RETURN_CODE(SP_ERR_SUPP); \
-	} \
-} while (0)
-#define RETURN_OK() RETURN_CODE(SP_OK);
-#define RETURN_ERROR(err, ...) do { DEBUG_ERROR(err, __VA_ARGS__); return err; } while (0)
-#define RETURN_FAIL(...) do { DEBUG_FAIL(__VA_ARGS__); return SP_ERR_FAIL; } while (0)
-#define RETURN_VALUE(fmt, x) do { \
-	typeof(x) _x = x; \
-	DEBUG("%s returning " fmt, __func__, _x); \
-	return _x; \
-} while (0)
-#define SET_ERROR(val, err, msg) do { DEBUG_ERROR(err, msg); val = err; } while (0)
-#define SET_FAIL(val, msg) do { DEBUG_FAIL(msg); val = SP_ERR_FAIL; } while (0)
-#define TRACE(fmt, ...) DEBUG("%s(" fmt ") called", __func__, ##__VA_ARGS__)
-
-#define TRY(x) do { int ret = x; if (ret != SP_OK) RETURN_CODEVAL(ret); } while (0)
+void (*sp_debug_handler)(const char *format, ...) = sp_default_debug_handler;
 
-/* Helper functions. */
-static struct sp_port **list_append(struct sp_port **list, const char *portname);
 static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 	struct sp_port_config *config);
+
 static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	const struct sp_port_config *config);
 
-enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
+SP_API enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_ptr)
 {
 	struct sp_port *port;
-	int len;
+#ifndef NO_PORT_METADATA
+	enum sp_return ret;
+#endif
+	size_t len;
 
 	TRACE("%s, %p", portname, port_ptr);
 
@@ -218,7 +71,21 @@ enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_p
 	if (!portname)
 		RETURN_ERROR(SP_ERR_ARG, "Null port name");
 
-	DEBUG("Building structure for port %s", portname);
+	DEBUG_FMT("Building structure for port %s", portname);
+
+#if !defined(_WIN32) && defined(HAVE_REALPATH)
+	/*
+	 * get_port_details() below tries to be too smart and figure out
+	 * some transport properties from the port name which breaks with
+	 * symlinks. Therefore we canonicalize the portname first.
+	 */
+	char pathbuf[PATH_MAX + 1];
+	char *res = realpath(portname, pathbuf);
+	if (!res)
+		RETURN_ERROR(SP_ERR_ARG, "Could not retrieve realpath behind port name");
+
+	portname = pathbuf;
+#endif
 
 	if (!(port = malloc(sizeof(struct sp_port))))
 		RETURN_ERROR(SP_ERR_MEM, "Port structure malloc failed");
@@ -233,32 +100,154 @@ enum sp_return sp_get_port_by_name(const char *portname, struct sp_port **port_p
 	memcpy(port->name, portname, len);
 
 #ifdef _WIN32
+	port->usb_path = NULL;
 	port->hdl = INVALID_HANDLE_VALUE;
+	port->write_buf = NULL;
+	port->write_buf_size = 0;
 #else
 	port->fd = -1;
 #endif
 
+	port->description = NULL;
+	port->transport = SP_TRANSPORT_NATIVE;
+	port->usb_bus = -1;
+	port->usb_address = -1;
+	port->usb_vid = -1;
+	port->usb_pid = -1;
+	port->usb_manufacturer = NULL;
+	port->usb_product = NULL;
+	port->usb_serial = NULL;
+	port->bluetooth_address = NULL;
+
+#ifndef NO_PORT_METADATA
+	if ((ret = get_port_details(port)) != SP_OK) {
+		sp_free_port(port);
+		return ret;
+	}
+#endif
+
 	*port_ptr = port;
 
 	RETURN_OK();
 }
 
-char *sp_get_port_name(const struct sp_port *port)
+SP_API char *sp_get_port_name(const struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	if (!port)
 		return NULL;
 
-	RETURN_VALUE("%s", port->name);
+	RETURN_STRING(port->name);
+}
+
+SP_API char *sp_get_port_description(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port || !port->description)
+		return NULL;
+
+	RETURN_STRING(port->description);
+}
+
+SP_API enum sp_transport sp_get_port_transport(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	RETURN_INT(port ? port->transport : SP_TRANSPORT_NATIVE);
+}
+
+SP_API enum sp_return sp_get_port_usb_bus_address(const struct sp_port *port,
+                                                  int *usb_bus,int *usb_address)
+{
+	TRACE("%p", port);
+
+	if (!port)
+		RETURN_ERROR(SP_ERR_ARG, "Null port");
+	if (port->transport != SP_TRANSPORT_USB)
+		RETURN_ERROR(SP_ERR_ARG, "Port does not use USB transport");
+	if (port->usb_bus < 0 || port->usb_address < 0)
+		RETURN_ERROR(SP_ERR_SUPP, "Bus and address values are not available");
+
+	if (usb_bus)
+		*usb_bus = port->usb_bus;
+	if (usb_address)
+		*usb_address = port->usb_address;
+
+	RETURN_OK();
+}
+
+SP_API enum sp_return sp_get_port_usb_vid_pid(const struct sp_port *port,
+                                              int *usb_vid, int *usb_pid)
+{
+	TRACE("%p", port);
+
+	if (!port)
+		RETURN_ERROR(SP_ERR_ARG, "Null port");
+	if (port->transport != SP_TRANSPORT_USB)
+		RETURN_ERROR(SP_ERR_ARG, "Port does not use USB transport");
+	if (port->usb_vid < 0 || port->usb_pid < 0)
+		RETURN_ERROR(SP_ERR_SUPP, "VID:PID values are not available");
+
+	if (usb_vid)
+		*usb_vid = port->usb_vid;
+	if (usb_pid)
+		*usb_pid = port->usb_pid;
+
+	RETURN_OK();
+}
+
+SP_API char *sp_get_port_usb_manufacturer(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_manufacturer)
+		return NULL;
+
+	RETURN_STRING(port->usb_manufacturer);
+}
+
+SP_API char *sp_get_port_usb_product(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_product)
+		return NULL;
+
+	RETURN_STRING(port->usb_product);
+}
+
+SP_API char *sp_get_port_usb_serial(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port || port->transport != SP_TRANSPORT_USB || !port->usb_serial)
+		return NULL;
+
+	RETURN_STRING(port->usb_serial);
+}
+
+SP_API char *sp_get_port_bluetooth_address(const struct sp_port *port)
+{
+	TRACE("%p", port);
+
+	if (!port || port->transport != SP_TRANSPORT_BLUETOOTH
+	    || !port->bluetooth_address)
+		return NULL;
+
+	RETURN_STRING(port->bluetooth_address);
 }
 
-enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr)
+SP_API enum sp_return sp_get_port_handle(const struct sp_port *port,
+                                         void *result_ptr)
 {
 	TRACE("%p, %p", port, result_ptr);
 
 	if (!port)
 		RETURN_ERROR(SP_ERR_ARG, "Null port");
+	if (!result_ptr)
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
 #ifdef _WIN32
 	HANDLE *handle_ptr = result_ptr;
@@ -271,7 +260,8 @@ enum sp_return sp_get_port_handle(const struct sp_port *port, void *result_ptr)
 	RETURN_OK();
 }
 
-enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_ptr)
+SP_API enum sp_return sp_copy_port(const struct sp_port *port,
+                                   struct sp_port **copy_ptr)
 {
 	TRACE("%p, %p", port, copy_ptr);
 
@@ -288,10 +278,10 @@ enum sp_return sp_copy_port(const struct sp_port *port, struct sp_port **copy_pt
 
 	DEBUG("Copying port structure");
 
-	RETURN_VALUE("%p", sp_get_port_by_name(port->name, copy_ptr));
+	RETURN_INT(sp_get_port_by_name(port->name, copy_ptr));
 }
 
-void sp_free_port(struct sp_port *port)
+SP_API void sp_free_port(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -304,18 +294,36 @@ void sp_free_port(struct sp_port *port)
 
 	if (port->name)
 		free(port->name);
+	if (port->description)
+		free(port->description);
+	if (port->usb_manufacturer)
+		free(port->usb_manufacturer);
+	if (port->usb_product)
+		free(port->usb_product);
+	if (port->usb_serial)
+		free(port->usb_serial);
+	if (port->bluetooth_address)
+		free(port->bluetooth_address);
+#ifdef _WIN32
+	if (port->usb_path)
+		free(port->usb_path);
+	if (port->write_buf)
+		free(port->write_buf);
+#endif
 
 	free(port);
 
 	RETURN();
 }
 
-static struct sp_port **list_append(struct sp_port **list, const char *portname)
+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++);
+	for (count = 0; list[count]; count++)
+		;
 	if (!(tmp = realloc(list, sizeof(struct sp_port *) * (count + 2))))
 		goto fail;
 	list = tmp;
@@ -329,240 +337,44 @@ fail:
 	return NULL;
 }
 
-enum sp_return sp_list_ports(struct sp_port ***list_ptr)
+SP_API enum sp_return sp_list_ports(struct sp_port ***list_ptr)
 {
+#ifndef NO_ENUMERATION
 	struct sp_port **list;
-	int ret = SP_ERR_SUPP;
+	int ret;
+#endif
 
 	TRACE("%p", list_ptr);
 
 	if (!list_ptr)
 		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
+	*list_ptr = NULL;
+
+#ifdef NO_ENUMERATION
+	RETURN_ERROR(SP_ERR_SUPP, "Enumeration not supported on this platform");
+#else
 	DEBUG("Enumerating ports");
 
-	if (!(list = malloc(sizeof(struct sp_port **))))
+	if (!(list = malloc(sizeof(struct sp_port *))))
 		RETURN_ERROR(SP_ERR_MEM, "Port list malloc failed");
 
 	list[0] = NULL;
 
-#ifdef _WIN32
-	HKEY key;
-	TCHAR *value, *data;
-	DWORD max_value_len, max_data_size, max_data_len;
-	DWORD value_len, data_size, data_len;
-	DWORD type, index = 0;
-	char *name;
-	int name_len;
-
-	ret = SP_OK;
-
-	DEBUG("Opening registry key");
-	if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("HARDWARE\\DEVICEMAP\\SERIALCOMM"),
-			0, KEY_QUERY_VALUE, &key) != ERROR_SUCCESS) {
-		SET_FAIL(ret, "RegOpenKeyEx() failed");
-		goto out_done;
-	}
-	DEBUG("Querying registry key value and data sizes");
-	if (RegQueryInfoKey(key, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
-				&max_value_len, &max_data_size, NULL, NULL) != ERROR_SUCCESS) {
-		SET_FAIL(ret, "RegQueryInfoKey() failed");
-		goto out_close;
-	}
-	max_data_len = max_data_size / sizeof(TCHAR);
-	if (!(value = malloc((max_value_len + 1) * sizeof(TCHAR)))) {
-		SET_ERROR(ret, SP_ERR_MEM, "registry value malloc failed");
-		goto out_close;
-	}
-	if (!(data = malloc((max_data_len + 1) * sizeof(TCHAR)))) {
-		SET_ERROR(ret, SP_ERR_MEM, "registry data malloc failed");
-		goto out_free_value;
-	}
-	DEBUG("Iterating over values");
-	while (
-		value_len = max_value_len + 1,
-		data_size = max_data_size,
-		RegEnumValue(key, index, value, &value_len,
-			NULL, &type, (LPBYTE)data, &data_size) == ERROR_SUCCESS)
-	{
-		data_len = data_size / sizeof(TCHAR);
-		data[data_len] = '\0';
-#ifdef UNICODE
-		name_len = WideCharToMultiByte(CP_ACP, 0, data, -1, NULL, 0, NULL, NULL);
-#else
-		name_len = data_len + 1;
-#endif
-		if (!(name = malloc(name_len))) {
-			SET_ERROR(ret, SP_ERR_MEM, "registry port name malloc failed");
-			goto out;
-		}
-#ifdef UNICODE
-		WideCharToMultiByte(CP_ACP, 0, data, -1, name, name_len, NULL, NULL);
-#else
-		strcpy(name, data);
-#endif
-		if (type == REG_SZ) {
-			DEBUG("Found port %s", name);
-			if (!(list = list_append(list, name))) {
-				SET_ERROR(ret, SP_ERR_MEM, "list append failed");
-				goto out;
-			}
-		}
-		index++;
-	}
-out:
-	free(data);
-out_free_value:
-	free(value);
-out_close:
-	RegCloseKey(key);
-out_done:
-#endif
-#ifdef __APPLE__
-	mach_port_t master;
-	CFMutableDictionaryRef classes;
-	io_iterator_t iter;
-	char *path;
-	io_object_t port;
-	CFTypeRef cf_path;
-	Boolean result;
-
-	ret = SP_OK;
-
-	DEBUG("Getting IOKit master port");
-	if (IOMasterPort(MACH_PORT_NULL, &master) != KERN_SUCCESS) {
-		SET_FAIL(ret, "IOMasterPort() failed");
-		goto out_done;
-	}
-
-	DEBUG("Creating matching dictionary");
-	if (!(classes = IOServiceMatching(kIOSerialBSDServiceValue))) {
-		SET_FAIL(ret, "IOServiceMatching() failed");
-		goto out_done;
-	}
-
-	CFDictionarySetValue(classes,
-			CFSTR(kIOSerialBSDTypeKey), CFSTR(kIOSerialBSDAllTypes));
-
-	DEBUG("Getting matching services");
-	if (IOServiceGetMatchingServices(master, classes, &iter) != KERN_SUCCESS) {
-		SET_FAIL(ret, "IOServiceGetMatchingServices() failed");
-		goto out_done;
-	}
-
-	if (!(path = malloc(PATH_MAX))) {
-		SET_ERROR(ret, SP_ERR_MEM, "device path malloc failed");
-		goto out_release;
-	}
-
-	DEBUG("Iterating over results");
-	while ((port = IOIteratorNext(iter))) {
-		cf_path = IORegistryEntryCreateCFProperty(port,
-				CFSTR(kIOCalloutDeviceKey), kCFAllocatorDefault, 0);
-		if (cf_path) {
-			result = CFStringGetCString(cf_path,
-					path, PATH_MAX, kCFStringEncodingASCII);
-			CFRelease(cf_path);
-			if (result) {
-				DEBUG("Found port %s", path);
-				if (!(list = list_append(list, path))) {
-					SET_ERROR(ret, SP_ERR_MEM, "list append failed");
-					IOObjectRelease(port);
-					goto out;
-				}
-			}
-		}
-		IOObjectRelease(port);
-	}
-out:
-	free(path);
-out_release:
-	IOObjectRelease(iter);
-out_done:
-#endif
-#if defined(__linux__) && defined(HAVE_LIBUDEV)
-	struct udev *ud;
-	struct udev_enumerate *ud_enumerate;
-	struct udev_list_entry *ud_list;
-	struct udev_list_entry *ud_entry;
-	const char *path;
-	struct udev_device *ud_dev, *ud_parent;
-	const char *name;
-	const char *driver;
-	int fd, ioctl_result;
-	struct serial_struct serial_info;
-
-	ret = SP_OK;
-
-	DEBUG("Enumerating tty devices");
-	ud = udev_new();
-	ud_enumerate = udev_enumerate_new(ud);
-	udev_enumerate_add_match_subsystem(ud_enumerate, "tty");
-	udev_enumerate_scan_devices(ud_enumerate);
-	ud_list = udev_enumerate_get_list_entry(ud_enumerate);
-	DEBUG("Iterating over results");
-	udev_list_entry_foreach(ud_entry, ud_list) {
-		path = udev_list_entry_get_name(ud_entry);
-		DEBUG("Found device %s", path);
-		ud_dev = udev_device_new_from_syspath(ud, path);
-		/* If there is no parent device, this is a virtual tty. */
-		ud_parent = udev_device_get_parent(ud_dev);
-		if (ud_parent == NULL) {
-			DEBUG("No parent device, assuming virtual tty");
-			udev_device_unref(ud_dev);
-			continue;
-		}
-		name = udev_device_get_devnode(ud_dev);
-		/* The serial8250 driver has a hardcoded number of ports.
-		 * The only way to tell which actually exist on a given system
-		 * is to try to open them and make an ioctl call. */
-		driver = udev_device_get_driver(ud_parent);
-		if (driver && !strcmp(driver, "serial8250")) {
-			DEBUG("serial8250 device, attempting to open");
-			if ((fd = open(name, O_RDWR | O_NONBLOCK | O_NOCTTY)) < 0) {
-				DEBUG("open failed, skipping");
-				goto skip;
-			}
-			ioctl_result = ioctl(fd, TIOCGSERIAL, &serial_info);
-			close(fd);
-			if (ioctl_result != 0) {
-				DEBUG("ioctl failed, skipping");
-				goto skip;
-			}
-			if (serial_info.type == PORT_UNKNOWN) {
-				DEBUG("port type is unknown, skipping");
-				goto skip;
-			}
-		}
-		DEBUG("Found port %s", name);
-		list = list_append(list, name);
-skip:
-		udev_device_unref(ud_dev);
-		if (!list) {
-			SET_ERROR(ret, SP_ERR_MEM, "list append failed");
-			goto out;
-		}
-	}
-out:
-	udev_enumerate_unref(ud_enumerate);
-	udev_unref(ud);
-#endif
+	ret = list_ports(&list);
 
-	switch (ret) {
-	case SP_OK:
+	if (ret == SP_OK) {
 		*list_ptr = list;
-		RETURN_OK();
-	case SP_ERR_SUPP:
-		DEBUG_ERROR(SP_ERR_SUPP, "Enumeration not supported on this platform");
-	default:
-		if (list)
-			sp_free_port_list(list);
+	} else {
+		sp_free_port_list(list);
 		*list_ptr = NULL;
-		return ret;
 	}
+
+	RETURN_CODEVAL(ret);
+#endif
 }
 
-void sp_free_port_list(struct sp_port **list)
+SP_API void sp_free_port_list(struct sp_port **list)
 {
 	unsigned int i;
 
@@ -583,20 +395,20 @@ void sp_free_port_list(struct sp_port **list)
 }
 
 #define CHECK_PORT() do { \
-	if (port == NULL) \
+	if (!port) \
 		RETURN_ERROR(SP_ERR_ARG, "Null port"); \
-	if (port->name == NULL) \
+	if (!port->name) \
 		RETURN_ERROR(SP_ERR_ARG, "Null port name"); \
 } while (0)
 #ifdef _WIN32
 #define CHECK_PORT_HANDLE() do { \
 	if (port->hdl == INVALID_HANDLE_VALUE) \
-		RETURN_ERROR(SP_ERR_ARG, "Invalid port handle"); \
+		RETURN_ERROR(SP_ERR_ARG, "Port not open"); \
 } while (0)
 #else
 #define CHECK_PORT_HANDLE() do { \
 	if (port->fd < 0) \
-		RETURN_ERROR(SP_ERR_ARG, "Invalid port fd"); \
+		RETURN_ERROR(SP_ERR_ARG, "Port not open"); \
 } while (0)
 #endif
 #define CHECK_OPEN_PORT() do { \
@@ -604,7 +416,44 @@ void sp_free_port_list(struct sp_port **list)
 	CHECK_PORT_HANDLE(); \
 } while (0)
 
-enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
+#ifdef WIN32
+/** To be called after port receive buffer is emptied. */
+static enum sp_return restart_wait(struct sp_port *port)
+{
+	DWORD wait_result;
+
+	if (port->wait_running) {
+		/* Check status of running wait operation. */
+		if (GetOverlappedResult(port->hdl, &port->wait_ovl,
+				&wait_result, FALSE)) {
+			DEBUG("Previous wait completed");
+			port->wait_running = FALSE;
+		} else if (GetLastError() == ERROR_IO_INCOMPLETE) {
+			DEBUG("Previous wait still running");
+			RETURN_OK();
+		} else {
+			RETURN_FAIL("GetOverlappedResult() failed");
+		}
+	}
+
+	if (!port->wait_running) {
+		/* Start new wait operation. */
+		if (WaitCommEvent(port->hdl, &port->events,
+				&port->wait_ovl)) {
+			DEBUG("New wait returned, events already pending");
+		} else if (GetLastError() == ERROR_IO_PENDING) {
+			DEBUG("New wait running in background");
+			port->wait_running = TRUE;
+		} else {
+			RETURN_FAIL("WaitCommEvent() failed");
+		}
+	}
+
+	RETURN_OK();
+}
+#endif
+
+SP_API enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 {
 	struct port_data data;
 	struct sp_port_config config;
@@ -614,10 +463,10 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 
 	CHECK_PORT();
 
-	if (flags > (SP_MODE_READ | SP_MODE_WRITE))
+	if (flags > SP_MODE_READ_WRITE)
 		RETURN_ERROR(SP_ERR_ARG, "Invalid flags");
 
-	DEBUG("Opening port %s", port->name);
+	DEBUG_FMT("Opening port %s", port->name);
 
 #ifdef _WIN32
 	DWORD desired_access = 0, flags_and_attributes = 0, errors;
@@ -636,13 +485,13 @@ 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);
 
 	if (port->hdl == INVALID_HANDLE_VALUE)
-		RETURN_FAIL("port CreateFile() failed");
+		RETURN_FAIL("Port CreateFile() failed");
 
 	/* All timeouts initially disabled. */
 	port->timeouts.ReadIntervalTimeout = 0;
@@ -677,21 +526,20 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 		RETURN_FAIL("SetCommMask() failed");
 	}
 
-	/* Start background operation for RX and error events. */
-	if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-		if (GetLastError() != ERROR_IO_PENDING) {
-			sp_close(port);
-			RETURN_FAIL("WaitCommEvent() failed");
-		}
-	}
-
 	port->writing = FALSE;
+	port->wait_running = FALSE;
+
+	ret = restart_wait(port);
 
+	if (ret < 0) {
+		sp_close(port);
+		RETURN_CODEVAL(ret);
+	}
 #else
-	int flags_local = O_NONBLOCK | O_NOCTTY;
+	int flags_local = O_NONBLOCK | O_NOCTTY | O_CLOEXEC;
 
 	/* Map 'flags' to the OS-specific settings. */
-	if (flags & (SP_MODE_READ | SP_MODE_WRITE))
+	if ((flags & SP_MODE_READ_WRITE) == SP_MODE_READ_WRITE)
 		flags_local |= O_RDWR;
 	else if (flags & SP_MODE_READ)
 		flags_local |= O_RDONLY;
@@ -700,6 +548,39 @@ 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);
@@ -709,13 +590,22 @@ 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;
 	data.dcb.fDsrSensitivity = FALSE;
 	data.dcb.fErrorChar = FALSE;
 	data.dcb.fNull = FALSE;
-	data.dcb.fAbortOnError = TRUE;
+	data.dcb.fAbortOnError = FALSE;
 #else
 	/* Turn off all fancy termios tricks, give us a raw channel. */
 	data.term.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IMAXBEL);
@@ -752,7 +642,8 @@ 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
@@ -770,18 +661,18 @@ enum sp_return sp_open(struct sp_port *port, enum sp_mode flags)
 	RETURN_OK();
 }
 
-enum sp_return sp_close(struct sp_port *port)
+SP_API enum sp_return sp_close(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Closing port %s", port->name);
+	DEBUG_FMT("Closing port %s", port->name);
 
 #ifdef _WIN32
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (CloseHandle(port->hdl) == 0)
-		RETURN_FAIL("port CloseHandle() failed");
+		RETURN_FAIL("Port CloseHandle() failed");
 	port->hdl = INVALID_HANDLE_VALUE;
 
 	/* Close event handles for overlapped structures. */
@@ -794,6 +685,10 @@ enum sp_return sp_close(struct sp_port *port)
 	CLOSE_OVERLAPPED(write_ovl);
 	CLOSE_OVERLAPPED(wait_ovl);
 
+	if (port->write_buf) {
+		free(port->write_buf);
+		port->write_buf = NULL;
+	}
 #else
 	/* Returns 0 upon success, -1 upon failure. */
 	if (close(port->fd) == -1)
@@ -804,7 +699,7 @@ enum sp_return sp_close(struct sp_port *port)
 	RETURN_OK();
 }
 
-enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
+SP_API enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 {
 	TRACE("%p, 0x%x", port, buffers);
 
@@ -815,7 +710,8 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 
 	const char *buffer_names[] = {"no", "input", "output", "both"};
 
-	DEBUG("Flushing %s buffers on port %s", buffer_names[buffers], port->name);
+	DEBUG_FMT("Flushing %s buffers on port %s",
+		buffer_names[buffers], port->name);
 
 #ifdef _WIN32
 	DWORD flags = 0;
@@ -827,13 +723,16 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 	/* Returns non-zero upon success, 0 upon failure. */
 	if (PurgeComm(port->hdl, flags) == 0)
 		RETURN_FAIL("PurgeComm() failed");
+
+	if (buffers & SP_BUF_INPUT)
+		TRY(restart_wait(port));
 #else
 	int flags = 0;
-	if (buffers & SP_BUF_BOTH)
+	if (buffers == SP_BUF_BOTH)
 		flags = TCIOFLUSH;
-	else if (buffers & SP_BUF_INPUT)
+	else if (buffers == SP_BUF_INPUT)
 		flags = TCIFLUSH;
-	else if (buffers & SP_BUF_OUTPUT)
+	else if (buffers == SP_BUF_OUTPUT)
 		flags = TCOFLUSH;
 
 	/* Returns 0 upon success, -1 upon failure. */
@@ -843,13 +742,13 @@ enum sp_return sp_flush(struct sp_port *port, enum sp_buffer buffers)
 	RETURN_OK();
 }
 
-enum sp_return sp_drain(struct sp_port *port)
+SP_API enum sp_return sp_drain(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Draining port %s", port->name);
+	DEBUG_FMT("Draining port %s", port->name);
 
 #ifdef _WIN32
 	/* Returns non-zero upon success, 0 upon failure. */
@@ -859,7 +758,9 @@ enum sp_return sp_drain(struct sp_port *port)
 #else
 	int result;
 	while (1) {
-#ifdef __ANDROID__
+#if defined(__ANDROID__) && (__ANDROID_API__ < 21)
+		/* Android only has tcdrain from platform 21 onwards.
+		 * On previous API versions, use the ioctl directly. */
 		int arg = 1;
 		result = ioctl(port->fd, TCSBRK, &arg);
 #else
@@ -879,88 +780,129 @@ enum sp_return sp_drain(struct sp_port *port)
 #endif
 }
 
-enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t count, unsigned int timeout)
+#ifdef _WIN32
+static enum sp_return await_write_completion(struct sp_port *port)
+{
+	TRACE("%p", port);
+	DWORD bytes_written;
+	BOOL result;
+
+	/* Wait for previous non-blocking write to complete, if any. */
+	if (port->writing) {
+		DEBUG("Waiting for previous write to complete");
+		result = GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
+		port->writing = 0;
+		if (!result)
+			RETURN_FAIL("Previous write failed to complete");
+		DEBUG("Previous write completed");
+	}
+
+	RETURN_OK();
+}
+#endif
+
+SP_API enum sp_return sp_blocking_write(struct sp_port *port, const void *buf,
+                                        size_t count, unsigned int timeout_ms)
 {
-	TRACE("%p, %p, %d, %d", port, buf, count, timeout);
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
 
 	CHECK_OPEN_PORT();
 
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	if (timeout)
-		DEBUG("Writing %d bytes to port %s, timeout %d ms", count, port->name, timeout);
+	if (timeout_ms)
+		DEBUG_FMT("Writing %d bytes to port %s, timeout %d ms",
+			count, port->name, timeout_ms);
 	else
-		DEBUG("Writing %d bytes to port %s, no timeout", count, port->name);
+		DEBUG_FMT("Writing %d bytes to port %s, no timeout",
+			count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD bytes_written = 0;
-	BOOL result;
+	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;
 
-	/* Wait for previous non-blocking write to complete, if any. */
-	if (port->writing) {
-		DEBUG("Waiting for previous write to complete");
-		result = GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
-		port->writing = 0;
-		if (!result)
-			RETURN_FAIL("Previous write failed to complete");
-		DEBUG("Previous write completed");
-	}
+	timeout_start(&timeout, timeout_ms);
 
-	/* Set timeout. */
-	port->timeouts.WriteTotalTimeoutConstant = timeout;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	TRY(await_write_completion(port));
 
-	/* Start write. */
-	if (WriteFile(port->hdl, buf, count, NULL, &port->write_ovl) == 0) {
-		if (GetLastError() == ERROR_IO_PENDING) {
+	while (total_bytes_written < count) {
+
+		if (timeout_check(&timeout))
+			break;
+
+		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");
-			GetOverlappedResult(port->hdl, &port->write_ovl, &bytes_written, TRUE);
-			DEBUG("Write completed, %d/%d bytes written", bytes_written, count);
-			RETURN_VALUE("%d", bytes_written);
+			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");
 		}
-	} else {
-		DEBUG("Write completed immediately");
-		RETURN_VALUE("%d", count);
+
+		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 timeval start, delta, now, end = {0, 0};
+	struct timeout timeout;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
-	if (timeout) {
-		/* Get time at start of operation. */
-		gettimeofday(&start, NULL);
-		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
-		/* Calculate time at which we should give up. */
-		timeradd(&start, &delta, &end);
-	}
+	timeout_start(&timeout, timeout_ms);
+
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
 
 	/* Loop until we have written the requested number of bytes. */
-	while (bytes_written < count)
-	{
-		/* Wait until space is available. */
-		FD_ZERO(&fds);
-		FD_SET(port->fd, &fds);
-		if (timeout) {
-			gettimeofday(&now, NULL);
-			if (timercmp(&now, &end, >)) {
-				DEBUG("write timed out");
-				RETURN_VALUE("%d", bytes_written);
-			}
-			timersub(&end, &now, &delta);
-		}
-		result = select(port->fd + 1, NULL, &fds, NULL, timeout ? &delta : NULL);
+	while (bytes_written < count) {
+
+		if (timeout_check(&timeout))
+			break;
+
+		result = select(port->fd + 1, NULL, &fds, NULL, timeout_timeval(&timeout));
+
+		timeout_update(&timeout);
+
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -969,8 +911,8 @@ enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t c
 				RETURN_FAIL("select() failed");
 			}
 		} else if (result == 0) {
-			DEBUG("write timed out");
-			RETURN_VALUE("%d", bytes_written);
+			/* Timeout has expired. */
+			break;
 		}
 
 		/* Do write. */
@@ -989,11 +931,15 @@ enum sp_return sp_blocking_write(struct sp_port *port, const void *buf, size_t c
 		ptr += result;
 	}
 
-	RETURN_VALUE("%d", bytes_written);
+	if (bytes_written < count)
+		DEBUG("Write timed out");
+
+	RETURN_INT(bytes_written);
 #endif
 }
 
-enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_t count)
+SP_API enum sp_return sp_nonblocking_write(struct sp_port *port,
+                                           const void *buf, size_t count)
 {
 	TRACE("%p, %p, %d", port, buf, count);
 
@@ -1002,14 +948,13 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	DEBUG("Writing up to %d bytes to port %s", count, port->name);
+	DEBUG_FMT("Writing up to %d bytes to port %s", count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD written = 0;
-	BYTE *ptr = (BYTE *) buf;
+	size_t buf_bytes;
 
 	/* Check whether previous write is complete. */
 	if (port->writing) {
@@ -1019,138 +964,151 @@ enum sp_return sp_nonblocking_write(struct sp_port *port, const void *buf, size_
 		} else {
 			DEBUG("Previous write not complete");
 			/* Can't take a new write until the previous one finishes. */
-			RETURN_VALUE("0", 0);
+			RETURN_INT(0);
 		}
 	}
 
 	/* Set timeout. */
-	port->timeouts.WriteTotalTimeoutConstant = 0;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.WriteTotalTimeoutConstant != 0) {
+		port->timeouts.WriteTotalTimeoutConstant = 0;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
-	/* Keep writing data until the OS has to actually start an async IO for it.
-	 * At that point we know the buffer is full. */
-	while (written < count)
-	{
-		/* Copy first byte of user buffer. */
-		port->pending_byte = *ptr++;
-
-		/* Start asynchronous write. */
-		if (WriteFile(port->hdl, &port->pending_byte, 1, NULL, &port->write_ovl) == 0) {
-			if (GetLastError() == ERROR_IO_PENDING) {
-				if (HasOverlappedIoCompleted(&port->write_ovl)) {
-					DEBUG("Asynchronous write completed immediately");
-					port->writing = 0;
-					written++;
-					continue;
-				} else {
-					DEBUG("Asynchronous write running");
-					port->writing = 1;
-					RETURN_VALUE("%d", ++written);
-				}
-			} else {
-				/* Actual failure of some kind. */
-				RETURN_FAIL("WriteFile() failed");
-			}
+	/* Reduce count if it exceeds the WriteFile limit. */
+	if (count > WRITEFILE_MAX_SIZE)
+		count = WRITEFILE_MAX_SIZE;
+
+	/* Copy data to our write buffer. */
+	buf_bytes = min(port->write_buf_size, count);
+	memcpy(port->write_buf, buf, buf_bytes);
+
+	/* Start asynchronous write. */
+	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");
+			else
+				DEBUG("Asynchronous write running");
 		} else {
-			DEBUG("Single byte written immediately");
-			written++;
+			/* Actual failure of some kind. */
+			RETURN_FAIL("WriteFile() failed");
 		}
 	}
 
 	DEBUG("All bytes written immediately");
 
-	RETURN_VALUE("%d", written);
+	RETURN_INT((int) buf_bytes);
 #else
 	/* Returns the number of bytes written, or -1 upon failure. */
 	ssize_t written = write(port->fd, buf, count);
 
-	if (written < 0)
-		RETURN_FAIL("write() failed");
-	else
-		RETURN_VALUE("%d", written);
+	if (written < 0) {
+		if (errno == EAGAIN)
+			// Buffer is full, no bytes written.
+			RETURN_INT(0);
+		else
+			RETURN_FAIL("write() failed");
+	} else {
+		RETURN_INT(written);
+	}
 #endif
 }
 
-enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, unsigned int timeout)
+#ifdef _WIN32
+/* Restart wait operation if buffer was emptied. */
+static enum sp_return restart_wait_if_needed(struct sp_port *port, unsigned int bytes_read)
 {
-	TRACE("%p, %p, %d, %d", port, buf, count, timeout);
+	DWORD errors;
+	COMSTAT comstat;
+
+	if (bytes_read == 0)
+		RETURN_OK();
+
+	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
+		RETURN_FAIL("ClearCommError() failed");
+
+	if (comstat.cbInQue == 0)
+		TRY(restart_wait(port));
+
+	RETURN_OK();
+}
+#endif
+
+SP_API enum sp_return sp_blocking_read(struct sp_port *port, void *buf,
+                                       size_t count, unsigned int timeout_ms)
+{
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
 
 	CHECK_OPEN_PORT();
 
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	if (timeout)
-		DEBUG("Reading %d bytes from port %s, timeout %d ms", count, port->name, timeout);
+	if (timeout_ms)
+		DEBUG_FMT("Reading %d bytes from port %s, timeout %d ms",
+			count, port->name, timeout_ms);
 	else
-		DEBUG("Reading %d bytes from port %s, no timeout", count, port->name);
+		DEBUG_FMT("Reading %d bytes from port %s, no timeout",
+			count, port->name);
 
 	if (count == 0)
-		RETURN_VALUE("0", 0);
+		RETURN_INT(0);
 
 #ifdef _WIN32
-	DWORD bytes_read = 0;
+	DWORD bytes_read;
 
 	/* Set timeout. */
-	port->timeouts.ReadIntervalTimeout = 0;
-	port->timeouts.ReadTotalTimeoutConstant = timeout;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.ReadIntervalTimeout != 0 ||
+			port->timeouts.ReadTotalTimeoutMultiplier != 0 ||
+			port->timeouts.ReadTotalTimeoutConstant != timeout_ms) {
+		port->timeouts.ReadIntervalTimeout = 0;
+		port->timeouts.ReadTotalTimeoutMultiplier = 0;
+		port->timeouts.ReadTotalTimeoutConstant = timeout_ms;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
 	/* Start read. */
-	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0) {
-		if (GetLastError() == ERROR_IO_PENDING) {
-			DEBUG("Waiting for read to complete");
-			GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE);
-			DEBUG("Read completed, %d/%d bytes read", bytes_read, count);
-		} else {
-			RETURN_FAIL("ReadFile() failed");
-		}
-	} else {
+	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)
+			RETURN_FAIL("GetOverlappedResult() failed");
+		DEBUG_FMT("Read completed, %d/%d bytes read", bytes_read, count);
+	} else {
+		RETURN_FAIL("ReadFile() failed");
 	}
 
-	/* Start background operation for subsequent events. */
-	if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-		if (GetLastError() != ERROR_IO_PENDING)
-			RETURN_FAIL("WaitCommEvent() failed");
-	}
+	TRY(restart_wait_if_needed(port, bytes_read));
 
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT((int) bytes_read);
 
 #else
 	size_t bytes_read = 0;
 	unsigned char *ptr = (unsigned char *) buf;
-	struct timeval start, delta, now, end = {0, 0};
+	struct timeout timeout;
 	fd_set fds;
-	int result;
+	ssize_t result;
 
-	if (timeout) {
-		/* Get time at start of operation. */
-		gettimeofday(&start, NULL);
-		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
-		/* Calculate time at which we should give up. */
-		timeradd(&start, &delta, &end);
-	}
+	timeout_start(&timeout, timeout_ms);
+
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
 
 	/* Loop until we have the requested number of bytes. */
-	while (bytes_read < count)
-	{
-		/* Wait until data is available. */
-		FD_ZERO(&fds);
-		FD_SET(port->fd, &fds);
-		if (timeout) {
-			gettimeofday(&now, NULL);
-			if (timercmp(&now, &end, >))
-				/* Timeout has expired. */
-				RETURN_VALUE("%d", bytes_read);
-			timersub(&end, &now, &delta);
-		}
-		result = select(port->fd + 1, &fds, NULL, NULL, timeout ? &delta : NULL);
+	while (bytes_read < count) {
+
+		if (timeout_check(&timeout))
+			/* Timeout has expired. */
+			break;
+
+		result = select(port->fd + 1, &fds, NULL, NULL, timeout_timeval(&timeout));
+
+		timeout_update(&timeout);
+
 		if (result < 0) {
 			if (errno == EINTR) {
 				DEBUG("select() call was interrupted, repeating");
@@ -1159,8 +1117,8 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 				RETURN_FAIL("select() failed");
 			}
 		} else if (result == 0) {
-			DEBUG("read timed out");
-			RETURN_VALUE("%d", bytes_read);
+			/* Timeout has expired. */
+			break;
 		}
 
 		/* Do read. */
@@ -1168,7 +1126,10 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 
 		if (result < 0) {
 			if (errno == EAGAIN)
-				/* This shouldn't happen because we did a select() first, but handle anyway. */
+				/*
+				 * This shouldn't happen because we did a
+				 * select() first, but handle anyway.
+				 */
 				continue;
 			else
 				/* This is an actual failure. */
@@ -1179,11 +1140,134 @@ enum sp_return sp_blocking_read(struct sp_port *port, void *buf, size_t count, u
 		ptr += result;
 	}
 
-	RETURN_VALUE("%d", bytes_read);
+	if (bytes_read < count)
+		DEBUG("Read timed out");
+
+	RETURN_INT(bytes_read);
+#endif
+}
+
+SP_API enum sp_return sp_blocking_read_next(struct sp_port *port, void *buf,
+                                            size_t count, unsigned int timeout_ms)
+{
+	TRACE("%p, %p, %d, %d", port, buf, count, timeout_ms);
+
+	CHECK_OPEN_PORT();
+
+	if (!buf)
+		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
+
+	if (count == 0)
+		RETURN_ERROR(SP_ERR_ARG, "Zero count");
+
+	if (timeout_ms)
+		DEBUG_FMT("Reading next max %d bytes from port %s, timeout %d ms",
+			count, port->name, timeout_ms);
+	else
+		DEBUG_FMT("Reading next max %d bytes from port %s, no timeout",
+			count, port->name);
+
+#ifdef _WIN32
+	DWORD bytes_read = 0;
+
+	/* If timeout_ms == 0, set maximum timeout. */
+	DWORD timeout_val = (timeout_ms == 0 ? MAXDWORD - 1 : timeout_ms);
+
+	/* Set timeout. */
+	if (port->timeouts.ReadIntervalTimeout != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutMultiplier != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutConstant != timeout_val) {
+		port->timeouts.ReadIntervalTimeout = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutMultiplier = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutConstant = timeout_val;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
+
+	/* Loop until we have at least one byte, or timeout is reached. */
+	while (bytes_read == 0) {
+		/* Start read. */
+		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");
+			if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
+				RETURN_FAIL("GetOverlappedResult() failed");
+			if (bytes_read > 0) {
+				DEBUG("Read completed");
+			} else if (timeout_ms > 0) {
+				DEBUG("Read timed out");
+				break;
+			} else {
+				DEBUG("Restarting read");
+			}
+		} else {
+			RETURN_FAIL("ReadFile() failed");
+		}
+	}
+
+	TRY(restart_wait_if_needed(port, bytes_read));
+
+	RETURN_INT(bytes_read);
+
+#else
+	size_t bytes_read = 0;
+	struct timeout timeout;
+	fd_set fds;
+	ssize_t result;
+
+	timeout_start(&timeout, timeout_ms);
+
+	FD_ZERO(&fds);
+	FD_SET(port->fd, &fds);
+
+	/* Loop until we have at least one byte, or timeout is reached. */
+	while (bytes_read == 0) {
+
+		if (timeout_check(&timeout))
+			/* Timeout has expired. */
+			break;
+
+		result = select(port->fd + 1, &fds, NULL, NULL, timeout_timeval(&timeout));
+
+		timeout_update(&timeout);
+
+		if (result < 0) {
+			if (errno == EINTR) {
+				DEBUG("select() call was interrupted, repeating");
+				continue;
+			} else {
+				RETURN_FAIL("select() failed");
+			}
+		} else if (result == 0) {
+			/* Timeout has expired. */
+			break;
+		}
+
+		/* Do read. */
+		result = read(port->fd, buf, count);
+
+		if (result < 0) {
+			if (errno == EAGAIN)
+				/* This shouldn't happen because we did a select() first, but handle anyway. */
+				continue;
+			else
+				/* This is an actual failure. */
+				RETURN_FAIL("read() failed");
+		}
+
+		bytes_read = result;
+	}
+
+	if (bytes_read == 0)
+		DEBUG("Read timed out");
+
+	RETURN_INT(bytes_read);
 #endif
 }
 
-enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count)
+SP_API enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf,
+                                          size_t count)
 {
 	TRACE("%p, %p, %d", port, buf, count);
 
@@ -1192,34 +1276,34 @@ enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count
 	if (!buf)
 		RETURN_ERROR(SP_ERR_ARG, "Null buffer");
 
-	DEBUG("Reading up to %d bytes from port %s", count, port->name);
+	DEBUG_FMT("Reading up to %d bytes from port %s", count, port->name);
 
 #ifdef _WIN32
 	DWORD bytes_read;
 
 	/* Set timeout. */
-	port->timeouts.ReadIntervalTimeout = MAXDWORD;
-	port->timeouts.ReadTotalTimeoutConstant = 0;
-	if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
-		RETURN_FAIL("SetCommTimeouts() failed");
+	if (port->timeouts.ReadIntervalTimeout != MAXDWORD ||
+			port->timeouts.ReadTotalTimeoutMultiplier != 0 ||
+			port->timeouts.ReadTotalTimeoutConstant != 0) {
+		port->timeouts.ReadIntervalTimeout = MAXDWORD;
+		port->timeouts.ReadTotalTimeoutMultiplier = 0;
+		port->timeouts.ReadTotalTimeoutConstant = 0;
+		if (SetCommTimeouts(port->hdl, &port->timeouts) == 0)
+			RETURN_FAIL("SetCommTimeouts() failed");
+	}
 
 	/* Do read. */
-	if (ReadFile(port->hdl, buf, count, NULL, &port->read_ovl) == 0)
-		RETURN_FAIL("ReadFile() failed");
+	if (ReadFile(port->hdl, buf, (DWORD) count, NULL, &port->read_ovl) == 0)
+		if (GetLastError() != ERROR_IO_PENDING)
+			RETURN_FAIL("ReadFile() failed");
 
 	/* Get number of bytes read. */
-	if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, TRUE) == 0)
+	if (GetOverlappedResult(port->hdl, &port->read_ovl, &bytes_read, FALSE) == 0)
 		RETURN_FAIL("GetOverlappedResult() failed");
 
-	if (bytes_read > 0) {
-		/* Start background operation for subsequent events. */
-		if (WaitCommEvent(port->hdl, &port->events, &port->wait_ovl) == 0) {
-			if (GetLastError() != ERROR_IO_PENDING)
-				RETURN_FAIL("WaitCommEvent() failed");
-		}
-	}
+	TRY(restart_wait_if_needed(port, bytes_read));
 
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT(bytes_read);
 #else
 	ssize_t bytes_read;
 
@@ -1232,17 +1316,17 @@ enum sp_return sp_nonblocking_read(struct sp_port *port, void *buf, size_t count
 			/* This is an actual failure. */
 			RETURN_FAIL("read() failed");
 	}
-	RETURN_VALUE("%d", bytes_read);
+	RETURN_INT(bytes_read);
 #endif
 }
 
-enum sp_return sp_input_waiting(struct sp_port *port)
+SP_API enum sp_return sp_input_waiting(struct sp_port *port)
 {
 	TRACE("%p", port);
 
 	CHECK_OPEN_PORT();
 
-	DEBUG("Checking input bytes waiting on port %s", port->name);
+	DEBUG_FMT("Checking input bytes waiting on port %s", port->name);
 
 #ifdef _WIN32
 	DWORD errors;
@@ -1250,22 +1334,27 @@ enum sp_return sp_input_waiting(struct sp_port *port)
 
 	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
 		RETURN_FAIL("ClearCommError() failed");
-	RETURN_VALUE("%d", comstat.cbInQue);
+	RETURN_INT(comstat.cbInQue);
 #else
 	int bytes_waiting;
 	if (ioctl(port->fd, TIOCINQ, &bytes_waiting) < 0)
 		RETURN_FAIL("TIOCINQ ioctl failed");
-	RETURN_VALUE("%d", bytes_waiting);
+	RETURN_INT(bytes_waiting);
 #endif
 }
 
-enum sp_return sp_output_waiting(struct sp_port *port)
+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("Checking output bytes waiting on port %s", port->name);
+	DEBUG_FMT("Checking output bytes waiting on port %s", port->name);
 
 #ifdef _WIN32
 	DWORD errors;
@@ -1273,16 +1362,17 @@ enum sp_return sp_output_waiting(struct sp_port *port)
 
 	if (ClearCommError(port->hdl, &errors, &comstat) == 0)
 		RETURN_FAIL("ClearCommError() failed");
-	RETURN_VALUE("%d", comstat.cbOutQue);
+	RETURN_INT(comstat.cbOutQue);
 #else
 	int bytes_waiting;
 	if (ioctl(port->fd, TIOCOUTQ, &bytes_waiting) < 0)
 		RETURN_FAIL("TIOCOUTQ ioctl failed");
-	RETURN_VALUE("%d", bytes_waiting);
+	RETURN_INT(bytes_waiting);
+#endif
 #endif
 }
 
-enum sp_return sp_new_event_set(struct sp_event_set **result_ptr)
+SP_API enum sp_return sp_new_event_set(struct sp_event_set **result_ptr)
 {
 	struct sp_event_set *result;
 
@@ -1313,13 +1403,14 @@ static enum sp_return add_handle(struct sp_event_set *event_set,
 
 	if (!(new_handles = realloc(event_set->handles,
 			sizeof(event_handle) * (event_set->count + 1))))
-		RETURN_ERROR(SP_ERR_MEM, "handle array realloc() failed");
+		RETURN_ERROR(SP_ERR_MEM, "Handle array realloc() failed");
+
+	event_set->handles = new_handles;
 
 	if (!(new_masks = realloc(event_set->masks,
 			sizeof(enum sp_event) * (event_set->count + 1))))
-		RETURN_ERROR(SP_ERR_MEM, "mask array realloc() failed");
+		RETURN_ERROR(SP_ERR_MEM, "Mask array realloc() failed");
 
-	event_set->handles = new_handles;
 	event_set->masks = new_masks;
 
 	((event_handle *) event_set->handles)[event_set->count] = handle;
@@ -1330,7 +1421,7 @@ static enum sp_return add_handle(struct sp_event_set *event_set,
 	RETURN_OK();
 }
 
-enum sp_return sp_add_port_events(struct sp_event_set *event_set,
+SP_API enum sp_return sp_add_port_events(struct sp_event_set *event_set,
 	const struct sp_port *port, enum sp_event mask)
 {
 	TRACE("%p, %p, %d", event_set, port, mask);
@@ -1360,7 +1451,7 @@ enum sp_return sp_add_port_events(struct sp_event_set *event_set,
 	RETURN_OK();
 }
 
-void sp_free_event_set(struct sp_event_set *event_set)
+SP_API void sp_free_event_set(struct sp_event_set *event_set)
 {
 	TRACE("%p", event_set);
 
@@ -1381,22 +1472,24 @@ void sp_free_event_set(struct sp_event_set *event_set)
 	RETURN();
 }
 
-enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
+SP_API enum sp_return sp_wait(struct sp_event_set *event_set,
+                              unsigned int timeout_ms)
 {
-	TRACE("%p, %d", event_set, timeout);
+	TRACE("%p, %d", event_set, timeout_ms);
 
 	if (!event_set)
 		RETURN_ERROR(SP_ERR_ARG, "Null event set");
 
 #ifdef _WIN32
 	if (WaitForMultipleObjects(event_set->count, event_set->handles, FALSE,
-			timeout ? timeout : INFINITE) == WAIT_FAILED)
+			timeout_ms ? timeout_ms : INFINITE) == WAIT_FAILED)
 		RETURN_FAIL("WaitForMultipleObjects() failed");
 
 	RETURN_OK();
 #else
-	struct timeval start, delta, now, end = {0, 0};
-	int result, timeout_remaining;
+	struct timeout timeout;
+	int poll_timeout;
+	int result;
 	struct pollfd *pollfds;
 	unsigned int i;
 
@@ -1404,7 +1497,7 @@ enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
 		RETURN_ERROR(SP_ERR_MEM, "pollfds malloc() failed");
 
 	for (i = 0; i < event_set->count; i++) {
-		pollfds[i].fd = ((int *) event_set->handles)[i];
+		pollfds[i].fd = ((int *)event_set->handles)[i];
 		pollfds[i].events = 0;
 		pollfds[i].revents = 0;
 		if (event_set->masks[i] & SP_EVENT_RX_READY)
@@ -1415,30 +1508,24 @@ enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
 			pollfds[i].events |= POLLERR;
 	}
 
-	if (timeout) {
-		/* Get time at start of operation. */
-		gettimeofday(&start, NULL);
-		/* Define duration of timeout. */
-		delta.tv_sec = timeout / 1000;
-		delta.tv_usec = (timeout % 1000) * 1000;
-		/* Calculate time at which we should give up. */
-		timeradd(&start, &delta, &end);
-	}
+	timeout_start(&timeout, timeout_ms);
+	timeout_limit(&timeout, INT_MAX);
 
 	/* Loop until an event occurs. */
-	while (1)
-	{
-		if (timeout) {
-			gettimeofday(&now, NULL);
-			if (timercmp(&now, &end, >)) {
-				DEBUG("wait timed out");
-				break;
-			}
-			timersub(&end, &now, &delta);
-			timeout_remaining = delta.tv_sec * 1000 + delta.tv_usec / 1000;
+	while (1) {
+
+		if (timeout_check(&timeout)) {
+			DEBUG("Wait timed out");
+			break;
 		}
 
-		result = poll(pollfds, event_set->count, timeout ? timeout_remaining : -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) {
@@ -1450,7 +1537,8 @@ enum sp_return sp_wait(struct sp_event_set *event_set, unsigned int timeout)
 			}
 		} else if (result == 0) {
 			DEBUG("poll() timed out");
-			break;
+			if (!timeout.overflow)
+				break;
 		} else {
 			DEBUG("poll() completed");
 			break;
@@ -1476,7 +1564,7 @@ static enum sp_return get_baudrate(int fd, int *baudrate)
 
 	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("getting termios failed");
+		RETURN_FAIL("Getting termios failed");
 	}
 
 	*baudrate = get_termios_speed(data);
@@ -1499,7 +1587,7 @@ static enum sp_return set_baudrate(int fd, int baudrate)
 
 	if (ioctl(fd, get_termios_get_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("getting termios failed");
+		RETURN_FAIL("Getting termios failed");
 	}
 
 	DEBUG("Setting baud rate");
@@ -1508,7 +1596,7 @@ static enum sp_return set_baudrate(int fd, int baudrate)
 
 	if (ioctl(fd, get_termios_set_ioctl(), data) < 0) {
 		free(data);
-		RETURN_FAIL("setting termios failed");
+		RETURN_FAIL("Setting termios failed");
 	}
 
 	free(data);
@@ -1531,7 +1619,7 @@ static enum sp_return get_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCGETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("getting termiox failed");
+		RETURN_FAIL("Getting termiox failed");
 	}
 
 	get_termiox_flow(termx, &data->rts_flow, &data->cts_flow,
@@ -1555,7 +1643,7 @@ static enum sp_return set_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCGETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("getting termiox failed");
+		RETURN_FAIL("Getting termiox failed");
 	}
 
 	DEBUG("Setting advanced flow control");
@@ -1565,7 +1653,7 @@ static enum sp_return set_flow(int fd, struct port_data *data)
 
 	if (ioctl(fd, TCSETX, termx) < 0) {
 		free(termx);
-		RETURN_FAIL("setting termiox failed");
+		RETURN_FAIL("Setting termiox failed");
 	}
 
 	free(termx);
@@ -1581,7 +1669,7 @@ static enum sp_return get_config(struct sp_port *port, struct port_data *data,
 
 	TRACE("%p, %p, %p", port, data, config);
 
-	DEBUG("Getting configuration for port %s", port->name);
+	DEBUG_FMT("Getting configuration for port %s", port->name);
 
 #ifdef _WIN32
 	if (!GetCommState(port->hdl, &data->dcb))
@@ -1600,28 +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:
@@ -1798,9 +1883,13 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
 	TRACE("%p, %p, %p", port, data, config);
 
-	DEBUG("Setting configuration for port %s", port->name);
+	DEBUG_FMT("Setting configuration for port %s", port->name);
 
 #ifdef _WIN32
+	BYTE* new_buf;
+
+	TRY(await_write_completion(port));
+
 	if (config->baudrate >= 0) {
 		for (i = 0; i < NUM_STD_BAUDRATES; i++) {
 			if (config->baudrate == std_baudrates[i].value) {
@@ -1811,6 +1900,13 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 
 		if (i == NUM_STD_BAUDRATES)
 			data->dcb.BaudRate = config->baudrate;
+
+		/* Allocate write buffer for 50ms of data at baud rate. */
+		port->write_buf_size = max(config->baudrate / (8 * 20), 1);
+		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)
@@ -2149,8 +2245,10 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	if (baud_nonstd != B0) {
 		if (ioctl(port->fd, IOSSIOSPEED, &baud_nonstd) == -1)
 			RETURN_FAIL("IOSSIOSPEED ioctl failed");
-		/* Set baud rates in data->term to correct, but incompatible
-		 * with tcsetattr() value, same as delivered by tcgetattr(). */
+		/*
+		 * Set baud rates in data->term to correct, but incompatible
+		 * with tcsetattr() value, same as delivered by tcgetattr().
+		 */
 		if (cfsetspeed(&data->term, baud_nonstd) < 0)
 			RETURN_FAIL("cfsetspeed() failed");
 	}
@@ -2170,7 +2268,7 @@ static enum sp_return set_config(struct sp_port *port, struct port_data *data,
 	RETURN_OK();
 }
 
-enum sp_return sp_new_config(struct sp_port_config **config_ptr)
+SP_API enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 {
 	struct sp_port_config *config;
 
@@ -2182,7 +2280,7 @@ enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 	*config_ptr = NULL;
 
 	if (!(config = malloc(sizeof(struct sp_port_config))))
-		RETURN_ERROR(SP_ERR_MEM, "config malloc failed");
+		RETURN_ERROR(SP_ERR_MEM, "Config malloc failed");
 
 	config->baudrate = -1;
 	config->bits = -1;
@@ -2198,7 +2296,7 @@ enum sp_return sp_new_config(struct sp_port_config **config_ptr)
 	RETURN_OK();
 }
 
-void sp_free_config(struct sp_port_config *config)
+SP_API void sp_free_config(struct sp_port_config *config)
 {
 	TRACE("%p", config);
 
@@ -2210,7 +2308,8 @@ void sp_free_config(struct sp_port_config *config)
 	RETURN();
 }
 
-enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config)
+SP_API enum sp_return sp_get_config(struct sp_port *port,
+                                    struct sp_port_config *config)
 {
 	struct port_data data;
 
@@ -2226,7 +2325,8 @@ enum sp_return sp_get_config(struct sp_port *port, struct sp_port_config *config
 	RETURN_OK();
 }
 
-enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *config)
+SP_API enum sp_return sp_set_config(struct sp_port *port,
+                                    const struct sp_port_config *config)
 {
 	struct port_data data;
 	struct sp_port_config prev_config;
@@ -2245,7 +2345,7 @@ enum sp_return sp_set_config(struct sp_port *port, const struct sp_port_config *
 }
 
 #define CREATE_ACCESSORS(x, type) \
-enum sp_return sp_set_##x(struct sp_port *port, type x) { \
+SP_API enum sp_return sp_set_##x(struct sp_port *port, type x) { \
 	struct port_data data; \
 	struct sp_port_config config; \
 	TRACE("%p, %d", port, x); \
@@ -2255,14 +2355,18 @@ enum sp_return sp_set_##x(struct sp_port *port, type x) { \
 	TRY(set_config(port, &data, &config)); \
 	RETURN_OK(); \
 } \
-enum sp_return sp_get_config_##x(const struct sp_port_config *config, type *x) { \
+SP_API enum sp_return sp_get_config_##x(const struct sp_port_config *config, \
+                                        type *x) { \
 	TRACE("%p, %p", config, x); \
+	if (!x) \
+		RETURN_ERROR(SP_ERR_ARG, "Null result pointer"); \
 	if (!config) \
 		RETURN_ERROR(SP_ERR_ARG, "Null config"); \
 	*x = config->x; \
 	RETURN_OK(); \
 } \
-enum sp_return sp_set_config_##x(struct sp_port_config *config, type x) { \
+SP_API enum sp_return sp_set_config_##x(struct sp_port_config *config, \
+                                        type x) { \
 	TRACE("%p, %d", config, x); \
 	if (!config) \
 		RETURN_ERROR(SP_ERR_ARG, "Null config"); \
@@ -2280,7 +2384,8 @@ CREATE_ACCESSORS(dtr, enum sp_dtr)
 CREATE_ACCESSORS(dsr, enum sp_dsr)
 CREATE_ACCESSORS(xon_xoff, enum sp_xonxoff)
 
-enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config, enum sp_flowcontrol flowcontrol)
+SP_API enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config,
+                                                enum sp_flowcontrol flowcontrol)
 {
 	if (!config)
 		RETURN_ERROR(SP_ERR_ARG, "Null configuration");
@@ -2314,7 +2419,8 @@ enum sp_return sp_set_config_flowcontrol(struct sp_port_config *config, enum sp_
 	RETURN_OK();
 }
 
-enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flowcontrol)
+SP_API enum sp_return sp_set_flowcontrol(struct sp_port *port,
+                                         enum sp_flowcontrol flowcontrol)
 {
 	struct port_data data;
 	struct sp_port_config config;
@@ -2332,7 +2438,8 @@ enum sp_return sp_set_flowcontrol(struct sp_port *port, enum sp_flowcontrol flow
 	RETURN_OK();
 }
 
-enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
+SP_API enum sp_return sp_get_signals(struct sp_port *port,
+                                     enum sp_signal *signals)
 {
 	TRACE("%p, %p", port, signals);
 
@@ -2341,7 +2448,7 @@ enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
 	if (!signals)
 		RETURN_ERROR(SP_ERR_ARG, "Null result pointer");
 
-	DEBUG("Getting control signals for port %s", port->name);
+	DEBUG_FMT("Getting control signals for port %s", port->name);
 
 	*signals = 0;
 #ifdef _WIN32
@@ -2372,7 +2479,7 @@ enum sp_return sp_get_signals(struct sp_port *port, enum sp_signal *signals)
 	RETURN_OK();
 }
 
-enum sp_return sp_start_break(struct sp_port *port)
+SP_API enum sp_return sp_start_break(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -2388,7 +2495,7 @@ enum sp_return sp_start_break(struct sp_port *port)
 	RETURN_OK();
 }
 
-enum sp_return sp_end_break(struct sp_port *port)
+SP_API enum sp_return sp_end_break(struct sp_port *port)
 {
 	TRACE("%p", port);
 
@@ -2404,41 +2511,44 @@ enum sp_return sp_end_break(struct sp_port *port)
 	RETURN_OK();
 }
 
-int sp_last_error_code(void)
+SP_API int sp_last_error_code(void)
 {
-	TRACE("");
+	TRACE_VOID();
 #ifdef _WIN32
-	RETURN_VALUE("%d", GetLastError());
+	RETURN_INT(GetLastError());
 #else
-	RETURN_VALUE("%d", errno);
+	RETURN_INT(errno);
 #endif
 }
 
-char *sp_last_error_message(void)
+SP_API char *sp_last_error_message(void)
 {
-	TRACE("");
+	TRACE_VOID();
 
 #ifdef _WIN32
-	LPVOID message;
+	char *message;
 	DWORD error = GetLastError();
 
-	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 );
 
-	RETURN_VALUE("%s", message);
+	if (length >= 2 && message[length - 2] == '\r')
+		message[length - 2] = '\0';
+
+	RETURN_STRING(message);
 #else
-	RETURN_VALUE("%s", strerror(errno));
+	RETURN_STRING(strerror(errno));
 #endif
 }
 
-void sp_free_error_message(char *message)
+SP_API void sp_free_error_message(char *message)
 {
 	TRACE("%s", message);
 
@@ -2451,7 +2561,7 @@ void sp_free_error_message(char *message)
 	RETURN();
 }
 
-void sp_set_debug_handler(void (*handler)(const char *format, ...))
+SP_API void sp_set_debug_handler(void (*handler)(const char *format, ...))
 {
 	TRACE("%p", handler);
 
@@ -2460,7 +2570,7 @@ void sp_set_debug_handler(void (*handler)(const char *format, ...))
 	RETURN();
 }
 
-void sp_default_debug_handler(const char *format, ...)
+SP_API void sp_default_debug_handler(const char *format, ...)
 {
 	va_list args;
 	va_start(args, format);
@@ -2471,42 +2581,42 @@ void sp_default_debug_handler(const char *format, ...)
 	va_end(args);
 }
 
-int sp_get_major_package_version(void)
+SP_API int sp_get_major_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MAJOR;
 }
 
-int sp_get_minor_package_version(void)
+SP_API int sp_get_minor_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MINOR;
 }
 
-int sp_get_micro_package_version(void)
+SP_API int sp_get_micro_package_version(void)
 {
 	return SP_PACKAGE_VERSION_MICRO;
 }
 
-const char *sp_get_package_version_string(void)
+SP_API const char *sp_get_package_version_string(void)
 {
 	return SP_PACKAGE_VERSION_STRING;
 }
 
-int sp_get_current_lib_version(void)
+SP_API int sp_get_current_lib_version(void)
 {
 	return SP_LIB_VERSION_CURRENT;
 }
 
-int sp_get_revision_lib_version(void)
+SP_API int sp_get_revision_lib_version(void)
 {
 	return SP_LIB_VERSION_REVISION;
 }
 
-int sp_get_age_lib_version(void)
+SP_API int sp_get_age_lib_version(void)
 {
 	return SP_LIB_VERSION_AGE;
 }
 
-const char *sp_get_lib_version_string(void)
+SP_API const char *sp_get_lib_version_string(void)
 {
 	return SP_LIB_VERSION_STRING;
 }