[PATCH] bootmenu: Allow to quit it via CTRL+C

[Heinrich Schuchardt]

Am 26. Dezember 2020 20:03:56 MEZ schrieb "Pali Rohár" <pali at kernel.org>:
>On Saturday 26 December 2020 19:44:23 Heinrich Schuchardt wrote:
>> Am 26. Dezember 2020 19:02:25 MEZ schrieb "Pali Rohár"
><pali at kernel.org>:
>> >When CTRL+C is pressed interrupt bootmenu and jump into U-Boot
>console.
>> >As the last entry in bootmenu is always U-Boot console just choose
>the
>> >last
>> >entry when CTRL+C is pressed.
>> >
>> >It is useful when bootmenu is part of boot process and you want to
>> >interrupt boot process by scripts which control U-Boot (serial)
>> >console.
>> 
>> Wouldn't the escape key be a better choice?
>
>I can add also escape key. But has escape key stable ANSI sequence
>which
>is needed to catch? If you tell me which bytes to catch (for escape
>key)
>I will add it.

0x1b is Escape

>
>> On the sandbox CTRL-C makes you quit U-Boot.
>> 
>> When hitting CTRL-C late on other systems it might interrupt a
>follow-up command.
>
>I understand your concerns. But all other commands catch also CTRL+C so
>I think that bootmenu command should it too.
>
>> --
>> 
>> The following is not directly related to your patch:
>> 
>> Is it really a good design that a user cannot be stopped from
>reaching the console?
>
>Currently "U-Boot console" option is always added to menu list. But
>option is doing only one thing: exiting the current U-Boot command and
>returning back to the monitor mode.
>
>> I could think of use cases in the context of secure booting where you
>want to show a menu but you do not want to give access to the command
>line.
>
>If bootmenu is not started from monitor mode then this "U-Boot console"
>command just enter into monitor mode. And I think that you can already
>block monitor mode and therefore has ability of this secure boot
>scheme.
>
>> Best regards
>> 
>> Heinrich
>> 
>> >
>> >Signed-off-by: Pali Rohár <pali at kernel.org>
>> >---
>> > cmd/bootmenu.c | 16 +++++++++++++++-
>> > 1 file changed, 15 insertions(+), 1 deletion(-)
>> >
>> >diff --git a/cmd/bootmenu.c b/cmd/bootmenu.c
>> >index 1ba7b622e5..9b56bfaa9a 100644
>> >--- a/cmd/bootmenu.c
>> >+++ b/cmd/bootmenu.c
>> >@@ -45,6 +45,7 @@ enum bootmenu_key {
>> > 	KEY_UP,
>> > 	KEY_DOWN,
>> > 	KEY_SELECT,
>> >+	KEY_QUIT,
>> > };
>> > 
>> > static char *bootmenu_getoption(unsigned short int n)
>> >@@ -109,6 +110,9 @@ static void bootmenu_autoboot_loop(struct
>> >bootmenu_data *menu,
>> > 			case '\r':
>> > 				*key = KEY_SELECT;
>> > 				break;
>> >+			case 0x3: /* ^C */
>> >+				*key = KEY_QUIT;
>> >+				break;
>> > 			default:
>> > 				*key = KEY_NONE;
>> > 				break;
>> >@@ -187,6 +191,10 @@ static void bootmenu_loop(struct bootmenu_data
>> >*menu,
>> > 	/* enter key was pressed */
>> > 	if (c == '\r')
>> > 		*key = KEY_SELECT;
>> >+
>> >+	/* ^C was pressed */
>> >+	if (c == 0x3)
>> >+		*key = KEY_QUIT;
>> > }
>> > 
>> > static char *bootmenu_choice_entry(void *data)
>> >@@ -222,6 +230,12 @@ static char *bootmenu_choice_entry(void *data)
>> > 			for (i = 0; i < menu->active; ++i)
>> > 				iter = iter->next;
>> > 			return iter->key;
>> >+		case KEY_QUIT:
>> >+			/* Quit by choosing the last entry - U-Boot console */
>> >+			iter = menu->first;
>> >+			while (iter->next)
>> >+				iter = iter->next;
>> >+			return iter->key;
>> > 		default:
>> > 			break;
>> > 		}
>> >@@ -389,7 +403,7 @@ static void menu_display_statusline(struct menu
>*m)
>> > 	printf(ANSI_CURSOR_POSITION, menu->count + 5, 1);
>> > 	puts(ANSI_CLEAR_LINE);
>> > 	printf(ANSI_CURSOR_POSITION, menu->count + 6, 1);
>> >-	puts("  Press UP/DOWN to move, ENTER to select");
>> >+	puts("  Press UP/DOWN to move, ENTER to select, CTRL+C to quit");
>> > 	puts(ANSI_CLEAR_LINE_TO_END);
>> > 	printf(ANSI_CURSOR_POSITION, menu->count + 7, 1);
>> > 	puts(ANSI_CLEAR_LINE);
>>