From 23ad4700a9464a6a625d46243ceb3a694f560399 Mon Sep 17 00:00:00 2001
From: Huang Qi <huangqi3@xiaomi.com>
Date: Wed, 17 May 2023 09:29:07 +0800
Subject: [PATCH] drivers/serial/pty.c: Fix coverity issue

Coverity report that `ntotal` may be a negative value.

Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
---
 drivers/serial/pty.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/serial/pty.c b/drivers/serial/pty.c
index 3db349cf4d7..249bb1a5844 100644
--- a/drivers/serial/pty.c
+++ b/drivers/serial/pty.c
@@ -471,7 +471,7 @@ static ssize_t pty_read(FAR struct file *filep, FAR char *buffer, size_t len)
       ntotal = file_read(&dev->pd_src, buffer, len);
     }
 
-  if (dev->pd_lflag & ECHO)
+  if ((dev->pd_lflag & ECHO) && (ntotal > 0))
     {
       pty_write(filep, buffer, ntotal);
     }