- if ((r = ioctl(fd, TIOCSCTTY, force)) < 0 &&
- (force || fail || errno != EPERM)) {
+ r = ioctl(fd, TIOCSCTTY, force);
+
+ /* Sometimes it makes sense to ignore TIOCSCTTY
+ * returning EPERM, i.e. when very likely we already
+ * are have this controlling terminal. */
+ if (r < 0 && errno == EPERM && ignore_tiocstty_eperm)
+ r = 0;
+
+ if (r < 0 && (force || fail || errno != EPERM)) {