Add -v/--version command flag

Author: cmaglie

args.go

@@ -0,0 +1,41 @@
+//
+// This file is part of serial-discovery.
+//
+// Copyright 2021 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to modify or
+// otherwise use the software for commercial activities involving the Arduino
+// software without disclosing the source code of your own applications. To purchase
+// a commercial license, send an email to license@arduino.cc.
+//
+
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+var args struct {
+	showVersion bool
+}
+
+func parseArgs() {
+	for _, arg := range os.Args[1:] {
+		if arg == "" {
+			continue
+		}
+		if arg == "-v" || arg == "--version" {
+			args.showVersion = true
+			continue
+		}
+		fmt.Fprintf(os.Stderr, "invalid argument: %s\n", arg)
+		os.Exit(1)
+	}
+}

main.go

@@ -1,7 +1,7 @@
 //
 // This file is part of serial-discovery.
 //
-// Copyright 2018 ARDUINO SA (http://www.arduino.cc/)
+// Copyright 2021 ARDUINO SA (http://www.arduino.cc/)
 //
 // This software is released under the GNU General Public License version 3,
 // which covers the main part of arduino-cli.
@@ -26,10 +26,17 @@ import (
 	"sync"
 
 	"github.com/arduino/go-properties-orderedmap"
+	"github.com/arduino/serial-discovery/version"
 	"go.bug.st/serial/enumerator"
 )
 
 func main() {
+	parseArgs()
+	if args.showVersion {
+		fmt.Printf("serial-discovery %s (build timestamp: %s)\n", version.Tag, version.Timestamp)
+		return
+	}
+
 	syncStarted := false
 	var syncCloseChan chan<- bool
 

version/version.go

@@ -0,0 +1,24 @@
+//
+// This file is part of serial-discovery.
+//
+// Copyright 2021 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to modify or
+// otherwise use the software for commercial activities involving the Arduino
+// software without disclosing the source code of your own applications. To purchase
+// a commercial license, send an email to license@arduino.cc.
+//
+
+package version
+
+// Tag is the current git tag
+var Tag = "snapshot"
+
+// Timestamp is the current timestamp
+var Timestamp = "unknown"