Add functions to achieve android support

fakelibusb_test.go

@@ -108,6 +108,16 @@ func (f *fakeLibusb) getDevices(*libusbContext) ([]*libusbDevice, error) {
 	return ret, nil
 }
 
+func (f *fakeLibusb) wrapSysDevice(ctx *libusbContext, systemDeviceHandle int) (*libusbDevHandle, error) {
+	//TODO should we do something for this
+	return nil, nil
+}
+
+func (f *fakeLibusb) getDevice(d *libusbDevHandle) (*libusbDevice, error) {
+	//TODO should we do something for this
+	return nil, nil
+}
+
 func (f *fakeLibusb) exit(*libusbContext) error {
 	close(f.submitted)
 	if got := len(f.ts); got > 0 {

libusb.go

@@ -143,6 +143,7 @@ type libusbIntf interface {
 	dereference(*libusbDevice)
 	getDeviceDesc(*libusbDevice) (*DeviceDesc, error)
 	open(*libusbDevice) (*libusbDevHandle, error)
+	wrapSysDevice(*libusbContext, int) (*libusbDevHandle, error)
 
 	close(*libusbDevHandle)
 	reset(*libusbDevHandle) error
@@ -152,6 +153,7 @@ type libusbIntf interface {
 	getStringDesc(*libusbDevHandle, int) (string, error)
 	setAutoDetach(*libusbDevHandle, int) error
 	detachKernelDriver(*libusbDevHandle, uint8) error
+	getDevice(*libusbDevHandle) (*libusbDevice, error)
 
 	// interface
 	claim(*libusbDevHandle, uint8) error
@@ -217,6 +219,24 @@ func (libusbImpl) getDevices(ctx *libusbContext) ([]*libusbDevice, error) {
 	return ret, nil
 }
 
+func (libusbImpl) wrapSysDevice(ctx *libusbContext, systemDeviceHandle int) (*libusbDevHandle, error) {
+	var handle *C.libusb_device_handle
+	if ret := C.libusb_wrap_sys_device((*C.libusb_context)(ctx), C.intptr_t(systemDeviceHandle), &handle); ret < 0 {
+		return nil, fromErrNo(C.int(ret))
+	}
+
+	return (*libusbDevHandle)(handle), nil
+}
+
+func (libusbImpl) getDevice(d *libusbDevHandle) (*libusbDevice, error) {
+	device := C.libusb_get_device((*C.libusb_device_handle)(d))
+	if device == nil {
+		return nil, fmt.Errorf("libusb_get_device failed")
+	}
+
+	return (*libusbDevice)(device), nil
+}
+
 func (libusbImpl) exit(c *libusbContext) error {
 	C.libusb_exit((*C.libusb_context)(c))
 	return nil

usb.go

@@ -128,6 +128,7 @@ import (
 	"errors"
 	"fmt"
 	"sync"
+	"syscall"
 )
 
 // Context manages all resources related to USB device handling.
@@ -210,6 +211,41 @@ func (c *Context) OpenDevices(opener func(desc *DeviceDesc) bool) ([]*Device, er
 	return ret, reterr
 }
 
+func (c *Context) OpenDeviceWithFileDescriptor(fileDescriptor string) (*Device, error) {
+	fd, err := syscall.Open(fileDescriptor, syscall.O_RDWR, 0)
+	if err != nil {
+		return nil, err
+	}
+
+	handle, err := c.libusb.wrapSysDevice(c.ctx, fd)
+	if err != nil {
+		return nil, err
+	}
+
+	dev, err := c.libusb.getDevice(handle)
+	if err != nil {
+		return nil, err
+	}
+
+	desc, err := c.libusb.getDeviceDesc(dev)
+	defer c.libusb.dereference(dev)
+	if err != nil {
+		return nil, err
+	}
+
+	handle, err = c.libusb.open(dev)
+	if err != nil {
+		return nil, err
+	}
+
+	o := &Device{handle: handle, ctx: c, Desc: desc}
+	c.mu.Lock()
+	c.devices[o] = true
+	c.mu.Unlock()
+
+	return o, nil
+}
+
 // OpenDeviceWithVIDPID opens Device from specific VendorId and ProductId.
 // If none is found, it returns nil and nil error. If there are multiple devices
 // with the same VID/PID, it will return one of them, picked arbitrarily.

usb_test.go

@@ -15,7 +15,9 @@
 
 package gousb
 
-import "testing"
+import (
+	"testing"
+)
 
 func TestOPenDevices(t *testing.T) {
 	t.Parallel()
@@ -94,3 +96,17 @@ func TestOpenDeviceWithVIDPID(t *testing.T) {
 		}
 	}
 }
+
+func TestOpenDeviceWithFileDescriptor(t *testing.T) {
+	ctx := NewContext()
+	defer ctx.Close()
+
+	descriptor := "/dev/bus/usb/001/002"
+	device, err := ctx.OpenDeviceWithFileDescriptor(descriptor)
+	if err != nil {
+		t.Errorf("OpenDeviceWithFileDescriptor: failed opening device %s", descriptor)
+	}
+
+	device.Close()
+
+}