Change how device is addressed, add alternative --bus/--addr flags.

Print all diagnostics to the log (stderr). Capture the data from
the specified endpoint and print it to stdout.

rawread/main.go

@@ -20,18 +20,23 @@ import (
 	"flag"
 	"fmt"
 	"log"
+	"os"
 
 	"github.com/kylelemons/gousb/usb"
 	"github.com/kylelemons/gousb/usbid"
 )
 
 var (
-	device   = flag.String("device", "vend:prod", "Device to which to connect")
+	vid      = flag.Uint("vid", 0, "VID of the device to which to connect. Exclusive with bus/addr flags.")
-	config   = flag.Int("config", 1, "Endpoint to which to connect")
+	pid      = flag.Uint("pid", 0, "PID of the device to which to connect. Exclusive with bus/addr flags.")
-	iface    = flag.Int("interface", 0, "Endpoint to which to connect")
+	bus      = flag.Uint("bus", 0, "Bus number for the device to which to connect. Exclusive with vid/pid flags.")
-	setup    = flag.Int("setup", 0, "Endpoint to which to connect")
+	addr     = flag.Uint("addr", 0, "Address of the device to which to connect. Exclusive with vid/pid flags.")
-	endpoint = flag.Int("endpoint", 1, "Endpoint to which to connect")
+	config   = flag.Uint("config", 1, "Endpoint to which to connect")
+	iface    = flag.Uint("interface", 0, "Endpoint to which to connect")
+	setup    = flag.Uint("setup", 0, "Endpoint to which to connect")
+	endpoint = flag.Uint("endpoint", 1, "Endpoint to which to connect")
 	debug    = flag.Int("debug", 3, "Debug level for libusb")
+	size     = flag.Uint("read_size", 1024, "Maximum number of bytes of data to read. Collected will be printed to STDOUT.")
 )
 
 func main() {
@@ -43,40 +48,29 @@ func main() {
 
 	ctx.Debug(*debug)
 
-	log.Printf("Scanning for device %q...", *device)
+	var devName string
+	switch {
+	case *vid == 0 && *pid == 0 && *bus == 0 && *addr == 0:
+		log.Fatal("You need to specify the device, either through --vid/--pid flags or through --bus/--addr flags.")
+	case (*vid > 0 || *pid > 0) && (*bus > 0 || *addr > 0):
+		log.Fatal("You can't use --vid/--pid flags at the same time as --bus/--addr.")
+	case *vid > 0 || *pid > 0:
+		devName = fmt.Sprintf("VID:PID %04x:%04x", *vid, *pid)
+	default:
+		devName = fmt.Sprintf("bus:addr %d:%d", *bus, *addr)
+	}
 
+	log.Printf("Scanning for device %q...", devName)
 	// ListDevices is used to find the devices to open.
 	devs, err := ctx.ListDevices(func(desc *usb.Descriptor) bool {
-		if fmt.Sprintf("%s:%s", desc.Vendor, desc.Product) != *device {
+		switch {
-			return false
+		case usb.ID(*vid) == desc.Vendor && usb.ID(*pid) == desc.Product:
+			return true
+		case uint8(*bus) == desc.Bus && uint8(*addr) == desc.Address:
+			return true
 		}
-
+		return false
-		// The usbid package can be used to print out human readable information.
-		fmt.Printf("  Protocol: %s\n", usbid.Classify(desc))
-
-		// The configurations can be examined from the Descriptor, though they can only
-		// be set once the device is opened.  All configuration references must be closed,
-		// to free up the memory in libusb.
-		for _, cfg := range desc.Configs {
-			// This loop just uses more of the built-in and usbid pretty printing to list
-			// the USB devices.
-			fmt.Printf("  %s:\n", cfg)
-			for _, alt := range cfg.Interfaces {
-				fmt.Printf("    --------------\n")
-				for _, iface := range alt.Setups {
-					fmt.Printf("    %s\n", iface)
-					fmt.Printf("      %s\n", usbid.Classify(iface))
-					for _, end := range iface.Endpoints {
-						fmt.Printf("      %s\n", end)
-					}
-				}
-			}
-			fmt.Printf("    --------------\n")
-		}
-
-		return true
 	})
-
 	// All Devices returned from ListDevices must be closed.
 	defer func() {
 		for _, d := range devs {
@@ -84,22 +78,56 @@ func main() {
 		}
 	}()
 
-	// ListDevices can occaionally fail, so be sure to check its return value.
+	// ListDevices can occasionally fail, so be sure to check its return value.
 	if err != nil {
-		log.Fatalf("list: %s", err)
+		log.Printf("Warning: ListDevices: %s.", err)
 	}
-
+	switch {
-	if len(devs) == 0 {
+	case len(devs) == 0:
-		log.Fatalf("no devices found")
+		log.Fatal("No matching devices found.")
+	case len(devs) > 1:
+		log.Printf("Warning: multiple devices found. Using bus %d, addr %d.", devs[0].Bus, devs[0].Address)
+		for _, d := range devs[1:] {
+			d.Close()
+		}
+		devs = devs[:1]
 	}
-
 	dev := devs[0]
 
+	// The usbid package can be used to print out human readable information.
+	log.Printf("  Protocol: %s\n", usbid.Classify(dev.Descriptor))
+
+	// The configurations can be examined from the Descriptor, though they can only
+	// be set once the device is opened.  All configuration references must be closed,
+	// to free up the memory in libusb.
+	for _, cfg := range dev.Configs {
+		// This loop just uses more of the built-in and usbid pretty printing to list
+		// the USB devices.
+		log.Printf("  %s:\n", cfg)
+		for _, alt := range cfg.Interfaces {
+			log.Printf("    --------------\n")
+			for _, iface := range alt.Setups {
+				log.Printf("    %s\n", iface)
+				log.Printf("      %s\n", usbid.Classify(iface))
+				for _, end := range iface.Endpoints {
+					log.Printf("      %s\n", end)
+				}
+			}
+		}
+		log.Printf("    --------------\n")
+	}
+
 	log.Printf("Connecting to endpoint...")
-	log.Printf("- %#v", dev.Descriptor)
 	ep, err := dev.OpenEndpoint(uint8(*config), uint8(*iface), uint8(*setup), uint8(*endpoint)|uint8(usb.ENDPOINT_DIR_IN))
 	if err != nil {
 		log.Fatalf("open: %s", err)
 	}
-	_ = ep
+
+	buf := make([]byte, *size)
+	num, err := ep.Read(buf)
+	if err != nil {
+		log.Fatalf("Reading from device failed: %v", err)
+	}
+	log.Printf("Read %d bytes of data", num)
+	os.Stdout.Write(buf[:num])
 }