From baf5509b59619051601f7d5271a95c5edb149dde Mon Sep 17 00:00:00 2001
From: Takumi Ando <t-ando@advaly.co.jp>
Date: Mon, 15 May 2023 17:44:46 +0900
Subject: [PATCH] nshlib: Add support for disabling echoback

If CONFIG_NSH_DISABLE_ECHOBACK is selected,
the NSH disables echoback prompt.

Signed-off-by: Takumi Ando <t-ando@advaly.co.jp>
---
 nshlib/Kconfig       |  6 ++++++
 nshlib/nsh_session.c | 16 ++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/nshlib/Kconfig b/nshlib/Kconfig
index 196af77a1..2ecefc6d7 100644
--- a/nshlib/Kconfig
+++ b/nshlib/Kconfig
@@ -70,6 +70,12 @@ config NSH_PROMPT_STRING
 	---help---
 		Provide the shell prompt string, default is "nsh> ".
 
+config NSH_DISABLE_ECHOBACK
+	bool "Disable echoback"
+	default n
+	---help---
+		If this option is selected, the NSH disables echoback.
+
 choice
 	prompt "Command Line Editor"
 	default NSH_READLINE if DEFAULT_SMALL
diff --git a/nshlib/nsh_session.c b/nshlib/nsh_session.c
index 4e5621552..4c254ddde 100644
--- a/nshlib/nsh_session.c
+++ b/nshlib/nsh_session.c
@@ -28,6 +28,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <termios.h>
 
 #ifdef CONFIG_NSH_CLE
 #  include "system/cle.h"
@@ -169,6 +170,21 @@ int nsh_session(FAR struct console_stdio_s *pstate,
         }
     }
 
+#ifdef CONFIG_NSH_DISABLE_ECHOBACK
+  /* Disable echoback */
+
+  if (isatty(INFD(pstate)))
+    {
+      struct termios cfg;
+
+      if (tcgetattr(INFD(pstate), &cfg) == 0)
+        {
+          cfg.c_lflag &= ~ECHO;
+          tcsetattr(INFD(pstate), TCSANOW, &cfg);
+        }
+    }
+#endif
+
   /* Then enter the command line parsing loop */
 
   for (; ; )