LoaderConfigTimeoutOneShot asks the boot loader to show the menu on the
next boot, and a value of 0 means the menu waits for the user. Sprout
treated it like LoaderConfigTimeout, so 0 hid the menu, the opposite of
what systemctl reboot --boot-loader-menu=0 asks for, and other values
only changed the timeout without forcing the menu.
Force the menu when the one-shot timeout is set, waiting for the user
when it is 0.
EFI string variables written without a trailing NUL, or with extra NUL
padding, failed to decode and were silently treated as unset. Decode up
to the first NUL and terminate the string ourselves, as systemd-boot
does.
Because empty values now decode to an empty string rather than failing,
treat empty LoaderEntryDefault and LoaderEntryOneShot values as unset so
an empty one-shot entry doesn't fail to match any entry.
A LoaderConfigTimeout or LoaderConfigTimeoutOneShot value that is not a
number or a known keyword made Sprout abort boot. Log a warning and
treat the variable as unset instead, matching systemd-boot.
alex