+static int verify_tty(const char *name) {
+ _cleanup_close_ int fd = -1;
+ const char *p;
+
+ /* Some TTYs are weird and have been enumerated but don't work
+ * when you try to use them, such as classic ttyS0 and
+ * friends. Let's check that and open the device and run
+ * isatty() on it. */
+
+ p = strjoina("/dev/", name);
+
+ /* O_NONBLOCK is essential here, to make sure we don't wait
+ * for DCD */
+ fd = open(p, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC|O_NOFOLLOW);
+ if (fd < 0)
+ return -errno;
+
+ errno = 0;
+ if (isatty(fd) <= 0)
+ return errno ? -errno : -EIO;
+
+ return 0;
+}
+