ADD: GetDescriptor

device.go

@@ -240,6 +240,18 @@ func (d *Device) GetStringDescriptor(descIndex int) (string, error) {
 	return d.ctx.libusb.getStringDesc(d.handle, descIndex)
 }
 
+// GetDescriptor returns a device descriptor with the given index number.
+func (d *Device) GetDescriptor(descIndex int) ([]byte, error) {
+	if d.handle == nil {
+		return nil, fmt.Errorf("GetDescriptor(%d) called on %s after Close", descIndex, d)
+	}
+	// descriptor index value of 0 indicates no string descriptor.
+	if descIndex == 0 {
+		return nil, nil
+	}
+	return d.ctx.libusb.getDescriptor(d.handle, descIndex)
+}
+
 // Manufacturer returns the device's manufacturer name.
 // GetStringDescriptor's string conversion rules apply.
 func (d *Device) Manufacturer() (string, error) {

libusb.go

@@ -150,6 +150,7 @@ type libusbIntf interface {
 	getConfig(*libusbDevHandle) (uint8, error)
 	setConfig(*libusbDevHandle, uint8) error
 	getStringDesc(*libusbDevHandle, int) (string, error)
+	getDescriptor(*libusbDevHandle, int) ([]byte, error)
 	setAutoDetach(*libusbDevHandle, int) error
 	detachKernelDriver(*libusbDevHandle, uint8) error
 
@@ -413,6 +414,22 @@ func (libusbImpl) getStringDesc(d *libusbDevHandle, index int) (string, error) {
 	return string(buf[:errno]), nil
 }
 
+func (libusbImpl) getDescriptor(d *libusbDevHandle, index int) ([]byte, error) {
+	// allocate 256-byte array limited the length of descriptor
+	buf := make([]byte, 256)
+	// get descriptor from libusb. if errno < 0 then there are any errors.
+	// if errno >= 0; it is a length of result descriptor
+	errno := C.libusb_get_descriptor(
+		(*C.libusb_device_handle)(d),
+		C.uint8_t(index), 0,
+		(*C.uchar)(unsafe.Pointer(&buf[0])),
+		256)
+	if errno < 0 {
+		return nil, fmt.Errorf("failed to get descriptor %d: %s", index, fromErrNo(errno))
+	}
+	return buf[:errno], nil
+}
+
 func (libusbImpl) setAutoDetach(d *libusbDevHandle, val int) error {
 	err := fromErrNo(C.libusb_set_auto_detach_kernel_driver((*C.libusb_device_handle)(d), C.int(val)))
 	if err != nil && err != ErrorNotSupported {