Extend the autodetach behavior

Detach interfaces before trying to change the config, as libusb doesn't handle that automatically.

AUTHORS

@@ -12,3 +12,4 @@ Jirawat I. <nodtem66@gmail.com>
 Thordur Bjornsson <thorduri@secnorth.net>
 Vincent Serpoul <vincent@serpoul.com>
 Josef Filzmaier <josef.filzmaier@gmail.com>
+Nico MT <nicovell3@gmail.com>

device.go

@@ -68,6 +68,9 @@ type Device struct {
 	// Claimed config
 	mu      sync.Mutex
 	claimed *Config
+
+	// Handle AutoDetach in this library
+	autodetach bool
 }
 
 func (d *DeviceDesc) sortedConfigIds() []int {
@@ -129,6 +132,14 @@ func (d *Device) Config(cfgNum int) (*Config, error) {
 		claimed: make(map[int]bool),
 	}
 
+	if d.autodetach {
+		for _, iface := range cfg.Desc.Interfaces {
+			if err := libusb.detachKernelDriver(d.handle, uint8(iface.Number)); err != nil {
+				return nil, fmt.Errorf("Can't detach kernel driver of the device %s and interface %d: %v", d, iface.Number, err)
+			}
+		}
+	}
+
 	if activeCfgNum, err := d.ActiveConfigNum(); err != nil {
 		return nil, fmt.Errorf("failed to query active config of the device %s: %v", d, err)
 	} else if cfgNum != activeCfgNum {
@@ -182,7 +193,7 @@ func (d *Device) Close() error {
 	d.mu.Lock()
 	defer d.mu.Unlock()
 	if d.claimed != nil {
-		return fmt.Errorf("can't release the device %s, it has an open config %s", d, d.claimed.Desc.Number)
+		return fmt.Errorf("can't release the device %s, it has an open config %d", d, d.claimed.Desc.Number)
 	}
 	libusb.close(d.handle)
 	d.handle = nil
@@ -208,12 +219,10 @@ func (d *Device) SetAutoDetach(autodetach bool) error {
 	if d.handle == nil {
 		return fmt.Errorf("SetAutoDetach(%v) called on %s after Close", autodetach, d)
 	}
+	d.autodetach = autodetach
 	var autodetachInt int
-	switch autodetach {
+	if autodetach {
-	case true:
 		autodetachInt = 1
-	case false:
-		autodetachInt = 0
 	}
 	return libusb.setAutoDetach(d.handle, autodetachInt)
 }

device_test.go

@@ -15,6 +15,7 @@
 package gousb
 
 import (
+	"errors"
 	"reflect"
 	"testing"
 )
@@ -42,6 +43,10 @@ func TestClaimAndRelease(t *testing.T) {
 	if err != nil {
 		t.Fatalf("OpenDeviceWithVIDPID(0x8888, 0x0002): %v", err)
 	}
+
+	if err = dev.SetAutoDetach(true); err != nil {
+		t.Fatalf("%s.SetAutoDetach(true): %v", dev, err)
+	}
 	cfg, err := dev.Config(cfgNum)
 	if err != nil {
 		t.Fatalf("%s.Config(1): %v", dev, err)
@@ -111,4 +116,49 @@ func TestClaimAndRelease(t *testing.T) {
 	if err := dev.Close(); err != nil {
 		t.Fatalf("%s.Close(): got error %v, want nil", dev, err)
 	}
+
+	if _, err := dev.Config(cfgNum); err == nil {
+		t.Fatalf("%s.Config(1): got error nil, want no nil because it is closed", dev)
+	}
+
+	if err := dev.Reset(); err == nil {
+		t.Fatalf("%s.Reset(): got error nil, want no nil because it is closed", dev)
+	}
+
+	if err := dev.SetAutoDetach(false); err == nil {
+		t.Fatalf("%s.SetAutoDetach(false): got error nil, want no nil because it is closed", dev)
+	}
+}
+
+type failDetachLib struct {
+	*fakeLibusb
+}
+
+func (*failDetachLib) detachKernelDriver(h *libusbDevHandle, i uint8) error {
+	if i == 1 {
+		return errors.New("test detach fail")
+	}
+	return nil
+}
+
+func TestAutoDetachFailure(t *testing.T) {
+	fake, done := newFakeLibusb()
+	defer done()
+	libusb = &failDetachLib{fake}
+
+	c := NewContext()
+	defer c.Close()
+	dev, err := c.OpenDeviceWithVIDPID(0x8888, 0x0002)
+	if dev == nil {
+		t.Fatal("OpenDeviceWithVIDPID(0x8888, 0x0002): got nil device, need non-nil")
+	}
+	defer dev.Close()
+	if err != nil {
+		t.Fatalf("OpenDeviceWithVIDPID(0x8888, 0x0002): %v", err)
+	}
+	dev.SetAutoDetach(true)
+	_, err = dev.Config(1)
+	if err == nil {
+		t.Fatalf("%s.Config(1) got nil, but want no nil because interface fails to detach", dev)
+	}
 }

endpoint_stream_test.go

@@ -76,6 +76,6 @@ func TestEndpointReadStream(t *testing.T) {
 		got += num
 	}
 	if got != want {
-		t.Errorf("%s.Read(): read %d bytes, want %d")
+		t.Errorf("stream.Read(): read %d bytes, want %d", got, want)
 	}
 }

fakelibusb_test.go

@@ -114,6 +114,8 @@ func (f *fakeLibusb) getStringDesc(*libusbDevHandle, int) (string, error) {
 }
 func (f *fakeLibusb) setAutoDetach(*libusbDevHandle, int) error { return nil }
 
+func (f *fakeLibusb) detachKernelDriver(*libusbDevHandle, uint8) error { return nil }
+
 func (f *fakeLibusb) claim(d *libusbDevHandle, intf uint8) error {
 	debug.Printf("claim(%p, %d)\n", d, intf)
 	f.mu.Lock()

libusb.go

@@ -148,6 +148,7 @@ type libusbIntf interface {
 	setConfig(*libusbDevHandle, uint8) error
 	getStringDesc(*libusbDevHandle, int) (string, error)
 	setAutoDetach(*libusbDevHandle, int) error
+	detachKernelDriver(*libusbDevHandle, uint8) error
 
 	// interface
 	claim(*libusbDevHandle, uint8) error
@@ -388,6 +389,16 @@ func (libusbImpl) setAutoDetach(d *libusbDevHandle, val int) error {
 	return nil
 }
 
+func (libusbImpl) detachKernelDriver(d *libusbDevHandle, iface uint8) error {
+	err := fromErrNo(C.libusb_detach_kernel_driver((*C.libusb_device_handle)(d), C.int(iface)))
+	if err != nil && err != ErrorNotSupported && err != ErrorNotFound {
+		// ErrorNotSupported is returned in non linux systems
+		// ErrorNotFound is returned if libusb's driver is already attached to the device
+		return err
+	}
+	return nil
+}
+
 func (libusbImpl) claim(d *libusbDevHandle, iface uint8) error {
 	return fromErrNo(C.libusb_claim_interface((*C.libusb_device_handle)(d), C.int(iface)))
 }