Added USB discovery for Linux

usb_linux.go

@@ -6,7 +6,102 @@
 
 package serial // import "go.bug.st/serial.v1"
 
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
 func nativeGetDetailedPortsList() ([]*PortDetails, error) {
-	// TODO
+	// Retrieve the port list
-	return nil, &PortError{code: FunctionNotImplemented}
+	ports, err := nativeGetPortsList()
+	if err != nil {
+		return nil, &PortError{code: ErrorEnumeratingPorts, causedBy: err}
+	}
+
+	var res []*PortDetails
+	for _, port := range ports {
+		details, err := nativeGetPortDetails(port)
+		if err != nil {
+			return nil, &PortError{code: ErrorEnumeratingPorts, causedBy: err}
+		}
+		res = append(res, details)
+	}
+	return res, nil
+}
+
+func nativeGetPortDetails(portPath string) (*PortDetails, error) {
+	portName := filepath.Base(portPath)
+	devicePath := fmt.Sprintf("/sys/class/tty/%s/device", portName)
+	if _, err := os.Stat(devicePath); err != nil {
+		return &PortDetails{}, nil
+	}
+	realDevicePath, err := filepath.EvalSymlinks(devicePath)
+	if err != nil {
+		return nil, fmt.Errorf("Can't determine real path of %s: %s", devicePath, err.Error())
+	}
+	subSystemPath, err := filepath.EvalSymlinks(filepath.Join(realDevicePath, "subsystem"))
+	if err != nil {
+		return nil, fmt.Errorf("Can't determine real path of %s: %s", filepath.Join(realDevicePath, "subsystem"), err.Error())
+	}
+	subSystem := filepath.Base(subSystemPath)
+
+	result := &PortDetails{Name: portPath}
+	switch subSystem {
+	case "usb-serial":
+		err := parseUSBSysFS(filepath.Dir(filepath.Dir(realDevicePath)), result)
+		return result, err
+	case "usb":
+		err := parseUSBSysFS(filepath.Dir(realDevicePath), result)
+		return result, err
+	// TODO: other cases?
+	default:
+		return result, nil
+	}
+}
+
+func parseUSBSysFS(usbDevicePath string, details *PortDetails) error {
+	vid, err := readLine(filepath.Join(usbDevicePath, "idVendor"))
+	if err != nil {
+		return err
+	}
+	pid, err := readLine(filepath.Join(usbDevicePath, "idProduct"))
+	if err != nil {
+		return err
+	}
+	serial, err := readLine(filepath.Join(usbDevicePath, "serial"))
+	if err != nil {
+		return err
+	}
+	manufacturer, err := readLine(filepath.Join(usbDevicePath, "manufacturer"))
+	if err != nil {
+		return err
+	}
+	product, err := readLine(filepath.Join(usbDevicePath, "product"))
+	if err != nil {
+		return err
+	}
+
+	details.IsUSB = true
+	details.VID = vid
+	details.PID = pid
+	details.SerialNumber = serial
+	details.Manufacturer = manufacturer
+	details.Product = product
+	return nil
+}
+
+func readLine(filename string) (string, error) {
+	file, err := os.Open(filename)
+	if os.IsNotExist(err) {
+		return "", nil
+	}
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+	reader := bufio.NewReader(file)
+	line, _, err := reader.ReadLine()
+	return string(line), err
 }