From 91f81d26653bbb01db93ad2929fc30cdf30f9ca4 Mon Sep 17 00:00:00 2001
From: Graham Christensen <graham@grahamc.com>
Date: Sun, 8 Feb 2026 10:05:20 -0500
Subject: [PATCH] Reject directory paths passed as tty device

When a directory path like /dev/foo is passed to tio, it silently
accepts it and appears to connect successfully, giving no indication
that the path is not a tty device. Check if the device path is a
directory before attempting to open it and exit with a clear error
message if so.

Fixes #359
---
 src/tty.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/tty.c b/src/tty.c
index efda859..6a95a97 100644
--- a/src/tty.c
+++ b/src/tty.c
@@ -2536,6 +2536,13 @@ int tty_connect(void)
     char*  now = NULL;
     struct timeval tval_before = {}, tval_now, tval_result;
 
+    /* Check that device is not a directory */
+    if (fs_dir_exists(device_name))
+    {
+        tio_error_printf("Device path '%s' is a directory, not a tty device", device_name);
+        exit(EXIT_FAILURE);
+    }
+
     /* Open tty device */
     device_fd = open(device_name, O_RDWR | O_NOCTTY | O_NONBLOCK);
     if (device_fd < 0)