Added port list functionality and increased range of baud rates available via serial_posix.go

posix_all.go

@@ -0,0 +1,119 @@
+// +build !windows
+
+package serial
+
+import (
+	"io/ioutil"
+	"regexp"
+	"strings"
+	"time"
+)
+
+const (
+	devFolder = "/dev"
+)
+
+
+// Converts the timeout values for Linux / POSIX systems
+// Moved to this new source module from serial.go
+func posixTimeoutValues(readTimeout time.Duration) (vmin uint8, vtime uint8) {
+	const MAXUINT8 = 1<<8 - 1 // 255
+	// set blocking / non-blocking read
+	var minBytesToRead uint8 = 1
+	var readTimeoutInDeci int64
+	if readTimeout > 0 {
+		// EOF on zero read
+		minBytesToRead = 0
+		// convert timeout to deciseconds as expected by VTIME
+		readTimeoutInDeci = (readTimeout.Nanoseconds() / 1e6 / 100)
+		// capping the timeout
+		if readTimeoutInDeci < 1 {
+			// min possible timeout 1 Deciseconds (0.1s)
+			readTimeoutInDeci = 1
+		} else if readTimeoutInDeci > MAXUINT8 {
+			// max possible timeout is 255 deciseconds (25.5s)
+			readTimeoutInDeci = MAXUINT8
+		}
+	}
+	return minBytesToRead, uint8(readTimeoutInDeci)
+}
+
+/*
+This function was taken with minor modifications from the go.bug.st/serial package (https://github.com/bugst/go-serial), and is subject to the conditions of its license (reproduced below):
+
+Copyright (c) 2014, Cristian Maglie.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in
+   the documentation and/or other materials provided with the
+   distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived
+   from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+func listPorts() ([]string, error) {
+	files, err := ioutil.ReadDir(devFolder)
+	if err != nil {
+		return nil, err
+	}
+
+	ports := make([]string, 0, len(files))
+	for _, f := range files {
+		// Skip folders
+		if f.IsDir() {
+			continue
+		}
+
+		// Keep only devices with name matching the port name filter defined for this platform
+		// (discarding placeholder entries for non-existent onboard COM ports)
+		match, err := regexp.MatchString(portNameFilter, f.Name())
+		if err != nil {
+			return nil, err
+		}
+		if !match || isALegacyPlaceholder(f.Name()) {
+			continue
+		}
+
+		// Save serial port in the resulting list
+		ports = append(ports, devFolder + "/" + f.Name())
+	}
+
+	return ports, nil
+}
+
+// Checks whether port entry is just a placeholder -- e.g. reserved for a legacy ISA COM
+// port that doesn't exist
+func isALegacyPlaceholder(portName string) (bool){
+	const legacyComPortPrefix = "ttyS"
+	if strings.HasPrefix(portName, legacyComPortPrefix) {
+		port, err := openPort(devFolder + "/" + portName, 9600, 100)
+		if err != nil {
+			return true;
+		} else {
+			port.Close()
+		}
+	}
+	return false;
+}

posix_darwin.go

@@ -0,0 +1,15 @@
+//+build darwin
+
+package serial
+
+//
+// Apparently OSX creates a CU (Call-Up) and a tty device entry for
+// each attached serial device, prefixing them with 'cu.' and 'tty.'
+// respectively
+// Should maybe restrict filter to cu devices?
+// (see http://pbxbook.com/other/mac-tty.html)
+// Although linux has dispensed with / deprecated this distinction:
+// http://tldp.org/HOWTO/Modem-HOWTO-9.html#ss9.8
+const (
+	portNameFilter = `^(cu|tty)\..*`
+)

posix_linux.go

@@ -0,0 +1,15 @@
+//+build linux
+
+package serial
+
+/*
+This heuristic regex filter should catch most serial devices under linux.
+The prefixes represent devices of the following types
+ttyS:   onboard uarts
+ttyUSB: USB<->uart bridges
+ttyACM: Abstract Control Model devices (e.g. modems -- see https://www.rfc1149.net/blog/2013/03/05/what-is-the-difference-between-devttyusbx-and-devttyacmx/)
+ttyAMA: Don't know what AMA stands for, but seems to be used for Raspberry PI onboard ports at least
+*/
+const (
+	portNameFilter = `^(ttyS|ttyUSB|ttyACM|ttyAMA)\d+`
+)

posix_other.go

@@ -0,0 +1,10 @@
+// +build !linux,!darwin
+
+package serial
+
+/*
+This is a catchall for posix platforms other than linux and OS X
+*/
+const (
+	portNameFilter = `^tty.*`
+)

serial.go

@@ -90,32 +90,18 @@ type Config struct {
 	// CRLFTranslate bool
 }
 
-// OpenPort opens a serial port with the specified configuration
 func OpenPort(c *Config) (*Port, error) {
 	return openPort(c.Name, c.Baud, c.ReadTimeout)
 }
 
-// Converts the timeout values for Linux / POSIX systems
-func posixTimeoutValues(readTimeout time.Duration) (vmin uint8, vtime uint8) {
-	const MAXUINT8 = 1<<8 - 1 // 255
-	// set blocking / non-blocking read
-	var minBytesToRead uint8 = 1
-	var readTimeoutInDeci int64
-	if readTimeout > 0 {
-		// EOF on zero read
-		minBytesToRead = 0
-		// convert timeout to deciseconds as expected by VTIME
-		readTimeoutInDeci = (readTimeout.Nanoseconds() / 1e6 / 100)
-		// capping the timeout
-		if readTimeoutInDeci < 1 {
-			// min possible timeout 1 Deciseconds (0.1s)
-			readTimeoutInDeci = 1
-		} else if readTimeoutInDeci > MAXUINT8 {
-			// max possible timeout is 255 deciseconds (25.5s)
-			readTimeoutInDeci = MAXUINT8
-		}
-	}
-	return minBytesToRead, uint8(readTimeoutInDeci)
+// ListPorts returns a list of serial ports identified on the system.
+// The windows implementation queries the registry and should be accurate.
+// The implementation for posix platforms just uses an heuristic approach, applying a regex
+// filter to the contents of /dev. Sensible defaults for linux and OS X have been defined in
+// 'posix_linux.go' and 'posix_darwin.go', respectively. On any other posix platform,
+// all devices matching the overly-inclusive pattern '^tty.*' will be returned.
+func ListPorts() ([]string, error) {
+	return listPorts()
 }
 
 // func SendBreak()

serial_posix.go

@@ -14,7 +14,6 @@ import (
 	"os"
 	"syscall"
 	"time"
-	//"unsafe"
 )
 
 func openPort(name string, baud int, readTimeout time.Duration) (p *Port, err error) {
@@ -55,7 +54,6 @@ func openPort(name string, baud int, readTimeout time.Duration) (p *Port, err er
 		f.Close()
 		return nil, fmt.Errorf("Unknown baud rate %v", baud)
 	}
-
 	_, err = C.cfsetispeed(&st, speed)
 	if err != nil {
 		f.Close()

serial_windows.go

@@ -3,6 +3,7 @@
 package serial
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"sync"
@@ -130,7 +131,83 @@ func (p *Port) Read(buf []byte) (int, error) {
 // Discards data written to the port but not transmitted,
 // or data received but not read
 func (p *Port) Flush() error {
-	return purgeComm(p.fd)
+	err := purgeComm(p.fd)
+	clearCommError(p.fd)
+	return err
+}
+
+/*
+This function was taken with minor modifications from the go.bug.st/serial package (https://github.com/bugst/go-serial), and is subject to the conditions of its license (reproduced below):
+
+Copyright (c) 2014, Cristian Maglie.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in
+   the documentation and/or other materials provided with the
+   distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived
+   from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+*/
+func listPorts() ([]string, error) {
+	subKey, err := syscall.UTF16PtrFromString("HARDWARE\\DEVICEMAP\\SERIALCOMM\\")
+	if err != nil {
+		return nil, errors.New("Error enumerating ports")
+	}
+
+	var h syscall.Handle
+	if syscall.RegOpenKeyEx(syscall.HKEY_LOCAL_MACHINE, subKey, 0, syscall.KEY_READ, &h) != nil {
+		return nil, errors.New("Error enumerating ports")
+	}
+	defer syscall.RegCloseKey(h)
+
+	var valuesCount uint32
+	if syscall.RegQueryInfoKey(h, nil, nil, nil, nil, nil, nil, &valuesCount, nil, nil, nil, nil) != nil {
+		return nil, errors.New("Error enumerating ports")
+	}
+
+	list := make([]string, valuesCount)
+	for i := range list {
+		var data [1024]uint16
+		dataSize := uint32(len(data))
+		var name [1024]uint16
+		nameSize := uint32(len(name))
+		if regEnumValue(h, uint32(i), &name[0], &nameSize, nil, nil, &data[0], &dataSize) != nil {
+			return nil, errors.New("Error enumerating ports")
+		}
+		list[i] = syscall.UTF16ToString(data[:])
+	}
+	return list, nil
+}
+
+func regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, value *uint16, valueLen *uint32) (regerrno error) {
+	r0, _, _ := syscall.Syscall9(nRegEnumValueW, 8, uintptr(key), uintptr(index), uintptr(unsafe.Pointer(name)), uintptr(unsafe.Pointer(nameLen)), uintptr(unsafe.Pointer(reserved)), uintptr(unsafe.Pointer(class)), uintptr(unsafe.Pointer(value)), uintptr(unsafe.Pointer(valueLen)), 0)
+	if r0 != 0 {
+		return syscall.Errno(r0)
+	}
+	return nil
 }
 
 var (
@@ -142,7 +219,9 @@ var (
 	nCreateEvent,
 	nResetEvent,
 	nPurgeComm,
-	nFlushFileBuffers uintptr
+	nFlushFileBuffers,
+	nClearCommError,
+	nRegEnumValueW uintptr
 )
 
 func init() {
@@ -151,6 +230,11 @@ func init() {
 		panic("LoadLibrary " + err.Error())
 	}
 	defer syscall.FreeLibrary(k32)
+	api32, err := syscall.LoadLibrary("advapi32.dll")
+	if err != nil {
+		panic("LoadLibrary " + err.Error())
+	}
+	defer syscall.FreeLibrary(api32)
 
 	nSetCommState = getProcAddr(k32, "SetCommState")
 	nSetCommTimeouts = getProcAddr(k32, "SetCommTimeouts")
@@ -161,6 +245,12 @@ func init() {
 	nResetEvent = getProcAddr(k32, "ResetEvent")
 	nPurgeComm = getProcAddr(k32, "PurgeComm")
 	nFlushFileBuffers = getProcAddr(k32, "FlushFileBuffers")
+	nClearCommError = getProcAddr(k32, "ClearCommError")
+	nRegEnumValueW = getProcAddr(api32, "RegEnumValueW")
+}
+
+func clearCommError(h syscall.Handle) error {
+	return processSyscall(nClearCommError, 1, uintptr(h), 0, 0)
 }
 
 func getProcAddr(lib syscall.Handle, name string) uintptr {
@@ -171,13 +261,24 @@ func getProcAddr(lib syscall.Handle, name string) uintptr {
 	return addr
 }
 
+func processSyscall(systemMethod, nargs, a1, a2, a3 uintptr) error {
+	result, _, err := syscall.Syscall(systemMethod, nargs, a1, a2, a3)
+	if result == 0 {
+		return err
+	}
+	return nil
+}
+
 func setCommState(h syscall.Handle, baud int) error {
 	var params structDCB
 	params.DCBlength = uint32(unsafe.Sizeof(params))
 
 	params.flags[0] = 0x01  // fBinary
 	params.flags[0] |= 0x10 // Assert DSR
 
+	//ADDITION: To help with this problem: http://zachsaw.blogspot.ie/2010/07/net-serialport-woes.html
+	params.flags[1] &= ^byte(0x40)
+
 	params.BaudRate = uint32(baud)
 	params.ByteSize = 8