From 81d063cb68c4582ec5288ebd1daa2b363d7a711a Mon Sep 17 00:00:00 2001
From: XANTRONIX Development <dev@xantronix.com>
Date: Sat, 1 Aug 2020 20:13:48 -0400
Subject: [PATCH] Skip tcgetattr() in patty_kiss_tnc_new_fd() w/ptmx

Modify patty_kiss_tnc_new_fd() to avoid tcgetattr()/tcsetattr() when
passed a file descriptor for a PTY master, to address incompatibility
with BSD kernelspace Unix98 PTY implementations
---
 src/kiss.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/kiss.c b/src/kiss.c
index a3945bb..64d44c9 100644
--- a/src/kiss.c
+++ b/src/kiss.c
@@ -52,7 +52,7 @@ patty_kiss_tnc *patty_kiss_tnc_new_fd(int fd) {
         goto error_malloc_buf;
     }
 
-    if (isatty(fd)) {
+    if (isatty(fd) && ptsname(fd) == NULL) {
         if (tcgetattr(fd, &tnc->attrs) < 0) {
             goto error_tcgetattr;
         }