simpler truncating

coadler · coadler · commit c3bae1c72237 · 2022-03-31T13:47:49.000-05:00
diff --git a/coderd/coderd.go b/coderd/coderd.go
@@ -212,25 +212,9 @@ func FmtWebsocketCloseMsg(format string, vars ...any) string {
 	// Cap msg length at 123 bytes. nhooyr/websocket only allows close messages
 	// of this length.
 	if len(msg) > websocketCloseMaxLen {
-		// truncateString safely truncates a string to a maximum size of byteLen. It
-		// writes whole runes until a single rune would increase the string size above
-		// byteLen.
-		truncateString := func(str string, byteLen int) string {
-			builder := strings.Builder{}
-			builder.Grow(byteLen)
-
-			for _, char := range str {
-				if builder.Len()+len(string(char)) > byteLen {
-					break
-				}
-
-				_, _ = builder.WriteRune(char)
-			}
-
-			return builder.String()
-		}
-
-		return truncateString(msg, websocketCloseMaxLen)
+		// Trim the string to 123 bytes. If we accidentally cut in the middle of
+		// a UTF-8 character, remove it from the string.
+		return strings.ToValidUTF8(string(msg[123]), "")
 	}
 
 	return msg
