Restrict file name to AlNum only

Fixes #20

migration/cleanname.go

@@ -1,21 +1,19 @@
 package migration
 
 import (
-	"os"
 	"strings"
+	"unicode"
 
 	"github.com/google/uuid"
 )
 
 // FileName returns sanitized filename without path delimiters
 func (op *Payload_OtpParameters) FileName() string {
 	return strings.Map(func(r rune) rune {
-		switch r {
-		case os.PathSeparator, os.PathListSeparator:
-			return '_'
-		default:
+		if unicode.IsLetter(r) || unicode.IsNumber(r) {
 			return r
 		}
+		return '_'
 	}, op.Name+"_"+op.Issuer)
 }
 

migration/cleanname_test.go

@@ -19,14 +19,14 @@ func TestFileName(t *testing.T) {
 				Name:   "A/B:C.d",
 				Issuer: "Issuer",
 			},
-			want: "A_B_C.d_Issuer",
+			want: "A_B_C_d_Issuer",
 		},
 		{
 			op: &Payload_OtpParameters{
 				Name:   "A/../B:C.d",
 				Issuer: "Issuer",
 			},
-			want: "A_.._B_C.d_Issuer",
+			want: "A____B_C_d_Issuer",
 		},
 	}