fix: handle empty sketch name

commands/sketch/new.go

@@ -37,7 +37,7 @@ void loop() {
 
 // sketchNameMaxLength could be part of the regex, but it's intentionally left out for clearer error reporting
 var sketchNameMaxLength = 63
-var sketchNameValidationRegex = regexp.MustCompile(`^[0-9a-zA-Z]{1}[0-9a-zA-Z_\.-]*$`)
+var sketchNameValidationRegex = regexp.MustCompile(`^[0-9a-zA-Z][0-9a-zA-Z_\.-]*$`)
 
 // NewSketch creates a new sketch via gRPC
 func NewSketch(ctx context.Context, req *rpc.NewSketchRequest) (*rpc.NewSketchResponse, error) {
@@ -71,12 +71,14 @@ func NewSketch(ctx context.Context, req *rpc.NewSketchRequest) (*rpc.NewSketchRe
 }
 
 func validateSketchName(name string) error {
+	if name == "" {
+		return &arduino.CantCreateSketchError{Cause: errors.New(tr("sketch name cannot be empty"))}
+	}
 	if len(name) > sketchNameMaxLength {
 		return &arduino.CantCreateSketchError{Cause: errors.New(tr("sketch name too long (%d characters). Maximum allowed length is %d",
 			len(name),
 			sketchNameMaxLength))}
 	}
-
 	if !sketchNameValidationRegex.MatchString(name) {
 		return &arduino.CantCreateSketchError{Cause: errors.New(tr("invalid sketch name \"%s\". Required pattern %s",
 			name,

commands/sketch/new_test.go

@@ -32,6 +32,17 @@ func Test_SketchNameWrongPattern(t *testing.T) {
 	}
 }
 
+func Test_SketchNameEmpty(t *testing.T) {
+	emptyName := ""
+	_, err := NewSketch(context.Background(), &commands.NewSketchRequest{
+		SketchName: emptyName,
+		SketchDir:  t.TempDir(),
+	})
+	require.NotNil(t, err)
+
+	require.Error(t, err, `Can't create sketch: sketch name cannot be empty`)
+}
+
 func Test_SketchNameTooLong(t *testing.T) {
 	tooLongName := make([]byte, sketchNameMaxLength+1)
 	for i := range tooLongName {

internal/cli/sketch/new.go

@@ -49,16 +49,33 @@ func initNewCommand() *cobra.Command {
 func runNewCommand(args []string, overwrite bool) {
 	logrus.Info("Executing `arduino-cli sketch new`")
 	// Trim to avoid issues if user creates a sketch adding the .ino extesion to the name
-	sketchName := args[0]
-	trimmedSketchName := strings.TrimSuffix(sketchName, globals.MainFileValidExtension)
-	sketchDirPath, err := paths.New(trimmedSketchName).Abs()
-	if err != nil {
-		feedback.Fatal(tr("Error creating sketch: %v", err), feedback.ErrGeneric)
+	inputSketchName := args[0]
+	trimmedSketchName := strings.TrimSuffix(inputSketchName, globals.MainFileValidExtension)
+
+	var sketchDir string
+	var sketchName string
+	var sketchDirPath *paths.Path
+	var err error
+
+	if trimmedSketchName == "" {
+		// `paths.New` returns nil with an empty string so `paths.Abs` panics.
+		// if the name is empty we rely on the "new" command to fail nicely later
+		// with the same logic in grpc and cli flows
+		sketchDir = ""
+		sketchName = ""
+	} else {
+		sketchDirPath, err = paths.New(trimmedSketchName).Abs()
+		if err != nil {
+			feedback.Fatal(tr("Error creating sketch: %v", err), feedback.ErrGeneric)
+		}
+		sketchDir = sketchDirPath.Parent().String()
+		sketchName = sketchDirPath.Base()
 	}
+
 	_, err = sk.NewSketch(context.Background(), &rpc.NewSketchRequest{
 		Instance:   nil,
-		SketchName: sketchDirPath.Base(),
-		SketchDir:  sketchDirPath.Parent().String(),
+		SketchName: sketchName,
+		SketchDir:  sketchDir,
 		Overwrite:  overwrite,
 	})
 	if err != nil {

internal/integrationtest/sketch/sketch_test.go

@@ -73,6 +73,16 @@ func TestSketchNew(t *testing.T) {
 	require.FileExists(t, currentSketchPath.Join(sketchName).String()+".ino")
 }
 
+func TestSketchNewEmptyName(t *testing.T) {
+	// testing that we fail nicely. It panicked in the past
+	env, cli := integrationtest.CreateArduinoCLIWithEnvironment(t)
+	defer env.CleanUp()
+
+	sketchName := ""
+	_, _, err := cli.Run("sketch", "new", sketchName)
+	require.Error(t, err, "Can't create sketch: sketch name cannot be empty")
+}
+
 func verifyZipContainsSketchExcludingBuildDir(t *testing.T, files []*zip.File) {
 	require.Len(t, files, 8)
 	require.Equal(t, paths.New("sketch_simple", "doc.txt").String(), files[0].Name)