Added hotplug support from libusb

go.mod

@@ -4,10 +4,12 @@ go 1.19
 
 require (
 	github.com/arduino/go-properties-orderedmap v1.7.1
+	github.com/arduino/go-win32-utils v1.0.0
 	github.com/arduino/pluggable-discovery-protocol-handler/v2 v2.1.1
 )
 
 require (
 	github.com/arduino/go-paths-helper v1.8.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
+	golang.org/x/sys v0.6.0 // indirect
 )

go.sum

@@ -52,6 +52,8 @@ github.com/arduino/go-properties-orderedmap v1.7.1 h1:HQ9Pn/mk3+XyfrE39EEvaZwJkr
 github.com/arduino/go-properties-orderedmap v1.7.1/go.mod h1:DKjD2VXY/NZmlingh4lSFMEYCVubfeArCsGPGDwb2yk=
 github.com/arduino/go-timeutils v0.0.0-20171220113728-d1dd9e313b1b/go.mod h1:uwGy5PpN4lqW97FiLnbcx+xx8jly5YuPMJWfVwwjJiQ=
 github.com/arduino/go-win32-utils v0.0.0-20180330194947-ed041402e83b/go.mod h1:iIPnclBMYm1g32Q5kXoqng4jLhMStReIP7ZxaoUC2y8=
+github.com/arduino/go-win32-utils v1.0.0 h1:/cXB86sOJxOsCHP7sQmXGLkdValwJt56mIwOHYxgQjQ=
+github.com/arduino/go-win32-utils v1.0.0/go.mod h1:0jqM7doGEAs6DaJCxxhLBUDS5OawrqF48HqXkcEie/Q=
 github.com/arduino/pluggable-discovery-protocol-handler/v2 v2.1.1 h1:MPQZ2YImq5qBiOPwTFGOrl6E99XGSRHc+UzHA6hsjvc=
 github.com/arduino/pluggable-discovery-protocol-handler/v2 v2.1.1/go.mod h1:2lA930B1Xu/otYT1kbx3l1n5vFJuuyPNkQaqOoQHmPE=
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
@@ -472,6 +474,8 @@ golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210823070655-63515b42dcdf/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.6.0 h1:MVltZSvRTcU2ljQOhs94SXPftV6DCNnZViHeQps87pQ=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=

main.c

@@ -79,3 +79,44 @@ void dfuProbeDevices() {
   clearDfuRoot();
   probe_devices(ctx);
 }
+
+volatile int has_event = 0;
+
+int libusbHandleEvents() {
+  struct timeval tv;
+  tv.tv_sec = 0;
+  tv.tv_usec = 500000;
+  libusb_handle_events_timeout_completed(ctx, &tv, NULL);
+  int res = has_event;
+  has_event = 0;
+  return res;
+}
+
+int callback(libusb_context *ctx, libusb_device *device, libusb_hotplug_event event, void *user_data) {
+  has_event = 1;
+  return 0;
+}
+
+libusb_hotplug_callback_handle callbackHandle;
+
+const char *libusbHotplugRegisterCallback() {
+  int err = libusb_hotplug_register_callback(
+    ctx,
+    LIBUSB_HOTPLUG_EVENT_DEVICE_ARRIVED | LIBUSB_HOTPLUG_EVENT_DEVICE_LEFT,
+    LIBUSB_HOTPLUG_NO_FLAGS,
+    LIBUSB_HOTPLUG_MATCH_ANY, // Vendor ID
+    LIBUSB_HOTPLUG_MATCH_ANY, // Product ID
+    LIBUSB_HOTPLUG_MATCH_ANY, // Device Class
+    callback,                 // Actual callback function
+    NULL,                     // User data
+    &callbackHandle
+  );
+  if (err != 0) {
+    return libusb_strerror(err);
+  }
+  return NULL;
+}
+
+void libusbHotplugDeregisterCallback() {
+  libusb_hotplug_deregister_callback(ctx, callbackHandle);
+}

main.go

@@ -18,8 +18,8 @@
 package main
 
 /*
-#cgo CPPFLAGS: -DHAVE_UNISTD_H -DHAVE_NANOSLEEP -DHAVE_ERR -I. -Idfu-util-0.11/src -I/usr/local/include/libusb-1.0
-#cgo CFLAGS: -DHAVE_UNISTD_H -DHAVE_NANOSLEEP -DHAVE_ERR -I. -Idfu-util-0.11/src -I/usr/local/include/libusb-1.0
+#cgo CPPFLAGS: -DHAVE_UNISTD_H -DHAVE_NANOSLEEP -DHAVE_ERR -I. -Idfu-util-0.11/src -I/usr/local/include/libusb-1.0 -Wall
+#cgo CFLAGS: -DHAVE_UNISTD_H -DHAVE_NANOSLEEP -DHAVE_ERR -I. -Idfu-util-0.11/src -I/usr/local/include/libusb-1.0 -Wall
 #cgo darwin LDFLAGS: -L/usr/local/lib -lusb-1.0 -framework IOKit -framework CoreFoundation -framework Security
 #cgo !darwin LDFLAGS: -L/usr/local/lib -lusb-1.0
 
@@ -32,13 +32,16 @@ char *get_path(libusb_device *dev);
 const char *libusbOpen();
 void libusbClose();
 void dfuProbeDevices();
+const char *libusbHotplugRegisterCallback();
+void libusbHotplugDeregisterCallback();
+int libusbHandleEvents();
 */
 import "C"
 
 import (
+	"errors"
 	"fmt"
 	"os"
-	"time"
 
 	"github.com/arduino/go-properties-orderedmap"
 	discovery "github.com/arduino/pluggable-discovery-protocol-handler/v2"
@@ -55,7 +58,7 @@ func main() {
 
 // DFUDiscovery is the implementation of the DFU pluggable-discovery
 type DFUDiscovery struct {
-	closeChan  chan<- struct{}
+	close      func()
 	portsCache map[string]*discovery.Port
 }
 
@@ -71,33 +74,46 @@ func (d *DFUDiscovery) Quit() {
 
 // Stop is the handler for the pluggable-discovery STOP command
 func (d *DFUDiscovery) Stop() error {
-	if d.closeChan != nil {
-		close(d.closeChan)
-		d.closeChan = nil
+	if d.close != nil {
+		d.close()
+		d.close = nil
 	}
 	C.libusbClose()
 	return nil
 }
 
 // StartSync is the handler for the pluggable-discovery START_SYNC command
 func (d *DFUDiscovery) StartSync(eventCB discovery.EventCallback, errorCB discovery.ErrorCallback) error {
+	d.portsCache = map[string]*discovery.Port{}
 	if cErr := C.libusbOpen(); cErr != nil {
 		return fmt.Errorf("can't open libusb: %s", C.GoString(cErr))
 	}
+	return d.sync(eventCB, errorCB)
+}
+
+func (d *DFUDiscovery) libusbSync(eventCB discovery.EventCallback, errorCB discovery.ErrorCallback) error {
+	if err := C.libusbHotplugRegisterCallback(); err != nil {
+		return errors.New(C.GoString(err))
+	}
+
 	closeChan := make(chan struct{})
 	go func() {
-		d.portsCache = map[string]*discovery.Port{}
+		d.sendUpdates(eventCB, errorCB)
 		for {
-			d.sendUpdates(eventCB, errorCB)
+			if C.libusbHandleEvents() != 0 {
+				d.sendUpdates(eventCB, errorCB)
+			}
 			select {
-			case <-time.After(5 * time.Second):
 			case <-closeChan:
-				d.portsCache = nil
+				C.libusbHotplugDeregisterCallback()
 				return
+			default:
 			}
 		}
 	}()
-	d.closeChan = closeChan
+	d.close = func() {
+		close(closeChan)
+	}
 	return nil
 }
 

sync_unix.go

@@ -0,0 +1,28 @@
+// This file is part of dfu-discovery.
+//
+// Copyright 2023 ARDUINO SA (http://www.arduino.cc/)
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+//go:build !windows
+
+package main
+
+import (
+	discovery "github.com/arduino/pluggable-discovery-protocol-handler/v2"
+)
+
+func (d *DFUDiscovery) sync(eventCB discovery.EventCallback, errorCB discovery.ErrorCallback) error {
+	return d.libusbSync(eventCB, errorCB)
+}

sync_windows.go

@@ -0,0 +1,71 @@
+// This file is part of dfu-discovery.
+//
+// Copyright 2023 ARDUINO SA (http://www.arduino.cc/)
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"context"
+	"time"
+
+	"github.com/arduino/go-win32-utils/devicenotification"
+	discovery "github.com/arduino/pluggable-discovery-protocol-handler/v2"
+)
+
+func (d *DFUDiscovery) sync(eventCB discovery.EventCallback, errorCB discovery.ErrorCallback) error {
+	ctx, cancel := context.WithCancel(context.Background())
+	d.close = cancel
+
+	deviceEventChan := make(chan bool, 1)
+	go func() {
+		err := devicenotification.Start(ctx, func() {
+			select {
+			case deviceEventChan <- true:
+			default:
+			}
+		}, errorCB)
+		if err != nil {
+			errorCB(err.Error())
+		}
+	}()
+
+	go func() {
+		d.sendUpdates(eventCB, errorCB)
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-deviceEventChan:
+			}
+
+		again:
+			d.sendUpdates(eventCB, errorCB)
+
+			// Trigger another update after 500ms because Windows might signal a
+			// new port much before it becomes actually available.
+			select {
+			case <-ctx.Done():
+				return
+			case <-deviceEventChan:
+				goto again
+			case <-time.After(time.Millisecond * 500):
+			}
+			d.sendUpdates(eventCB, errorCB)
+		}
+	}()
+	return nil
+}