[syslinux] RFC: Feature: MENU HIDDEN behaviour on ANY key

[David Henderson]

I too think it would be nice to define the keys to show the menu if desired!

Thanks,
Dave


On 4/10/19, Dany St-Amant via Syslinux <syslinux at syslinux.org> wrote:
> Hello,
>
> Here's a small enhancement feature for menu.c32. Looking for feedback before
> starting any coding (not sure when I'll have time for implementation)
>
> Regards,
> Dany St-Amant
>
>
> *Problem statement*
>
> When MENU HIDDEN is used on an headless server, any noise on the serial
> console can interrupt the boot; it would be preferable if there only
> specific keys were allowed to interrupt, reducing the probability of
> unwanted interruption. Even with TOTALTIMEOUT present, there's a delay
> present as TOTALTIMEOUT has to be large enough to make it useable during
> intentional boot interruption.
>
> *Basic behaviour change*
>
> Provide a way to assign "reveal menu" to specific key(s)
> Provide a default behaviour for unassigned keys (other than current "reveal
> menu")
>
> *Possible user interface change*
>
> MENU HIDDENMENUKEY key[,key]
> MENU HIDDDENKEY key[,key] [command...]
> Add ANY as an acceptable value for key
> Make command optional, defaulting to boot default.
>
> *Behaviour*
>
> If pressed key is defined by HIDDENKEY, that action is always taken.
> no HIDDENMENUKEY, no HIDDENKEY ANY: all keys bring the menu (current
> behaviour)
> HIDDENMENUKEY ANY: all keys bring the menu (current behaviour)
> HIDDENMENUKEY Esc, HIDDENKEY ANY (without commands): Esc brings the menu,
> all keys autoboot
> HIDDENMENUKEY Esc, no HIDDENKEY ANY: Esc brings the menu, all keys trigger
> nothing.
>
> *Exclusion*
>
> No similar support for boot prompt.
> No code/behaviour analysis made for cmenu.c32
>
> *Affected code* (outside config parsing)
>
> menumain.c:do_hidden_menu()
> Extra comparison when handling mygetkey(),ignoring unbound key if ANY not
> assigned (or defaulted). Return NULL, if hide_key[key] matches
> HIDDENMENUKEY. A few extra globals likely required to track/reference
> pseudo-commands "reveal menu" and "boot default" inside hide_key[] table.
> Need to use/steal an unused entry of hide_key[] as the ANY key.
>
> *Rejected/discarded interface option*
>
> MENU HIDDENSECUREKEY key[,key] [STRICT]
> MENU HIDDENDEFAULTKEY 0|1
> MENU HIDDENANYKEY MENU|IGNORE|BOOT
> MENU HIDDENKEY ANY|key[,key] MENU|IGNORE|BOOT|command...
>
> Last one is rejected to avoid collision with exiting configuration which
> might be using label matching the keywords.
>
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