+static bool on_tty(void) {
+ static int t = -1;
+
+ /* Note that this is invoked relatively early, before we start
+ * the pager. That means the value we return reflects whether
+ * we originally were started on a tty, not if we currently
+ * are. But this is intended, since we want colour and so on
+ * when run in our own pager. */
+
+ if (_unlikely_(t < 0))
+ t = isatty(STDOUT_FILENO) > 0;
+
+ return t;
+}
+