[PATCH] cli: flush stdin before enabling cli

[Gregor Herburger]

Currently there is no possibility to flush stdin after autocommands are
executed. If in the bootcmd the stdin is changed, e.g. from nulldev to
serial, it could happen that junk characters sit in the fifo and appear
on the cli.

Add a option to clear stdin before starting the CLI.

Signed-off-by: Gregor Herburger <gregor.herburger at linutronix.de>

---

 cmd/Kconfig  | 7 +++++++
 common/cli.c | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/cmd/Kconfig b/cmd/Kconfig
index 322ebe600c5..e08fbf27358 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -47,6 +47,13 @@ config HUSH_SELECTABLE
 	default y if HUSH_OLD_PARSER && HUSH_MODERN_PARSER
 endmenu
 
+config CMDLINE_FLUSH_STDIN
+	bool "Enable flushing input before starting cli"
+	default n
+	help
+	  When this option is enabled the stdin buffer will be flushed before
+	  starting the CLI.
+
 config CMDLINE_EDITING
 	bool "Enable command line editing"
 	default y
diff --git a/common/cli.c b/common/cli.c
index 4694a35cd0e..42d27ed87e7 100644
--- a/common/cli.c
+++ b/common/cli.c
@@ -295,6 +295,12 @@ err:
 void cli_loop(void)
 {
 	bootstage_mark(BOOTSTAGE_ID_ENTER_CLI_LOOP);
+
+	if (IS_ENABLED(CONFIG_CMDLINE_FLUSH_STDIN)) {
+		while (tstc())
+			(void)getchar();
+	}
+
 #if CONFIG_IS_ENABLED(HUSH_PARSER)
 	if (gd->flags & GD_FLG_HUSH_MODERN_PARSER)
 		parse_and_run_file();
-- 
2.47.3

base-commit: c704af3c8b0f37929bce8c2a4bba27d6e89919c7
branch: cmd-flush-stdin