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Author: Pali Rohár
Date:  
To: Heinrich Schuchardt
CC: Simon Glass, Thirupathaiah Annapureddy, u-boot, maemo-leste
Subject: Re: [maemo-leste] [PATCH] bootmenu: Allow to quit it via CTRL+C
On Saturday 26 December 2020 19:44:23 Heinrich Schuchardt wrote:
> Am 26. Dezember 2020 19:02:25 MEZ schrieb "Pali Rohár" <pali@???>:
> >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.

> 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@???>
> >---
> > 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);

>