run_scripts_optional sets 'y' value but call_scripts checks for 'optional' value

[Wladimir Mutel]

I looked into my initramfs and found there big graphics modules for hardware which I don't have.
I found a place where these modules were copied into initramfs, it was in /usr/share/initramfs-tools/hooks/framebuffer
Also I found a recipe on the Internet, advising to put 'FRAMEBUFFER=n' into initramfs.conf to exclude optional hooks and scipts which have OPTION=FRAMEBUFFER in them from initramfs creation
I tried to set this option and to update my initramfs, but did not succeed
So I examined mkinitramfs and related scripts and found this sequence in /usr/share/initramfs-tools/hook-functions :

run_scripts_optional()
{
        call_scripts_optional=y
        run_scripts "$@"
}
...
run_scripts()
{
...
        call_scripts $scriptdir
}
...
call_scripts()
{
...
        for cs_x in ${runlist}; do
...
                if [ x"$call_scripts_optional" = "xoptional" ]; then
                        option=$(sed '/^OPTION=/!d;$d;s/^OPTION=//;s/[[:space:]]*$//' "${initdir}/${cs_x}")
                        [ -z "${option}" ] || eval test -n \"\${$option}\" -a \"\${$option}\" != \"n\" || continue
                fi
...
        done
...
}

As you see, variable 'call_scripts_optional' is set to vaue 'y' in run_scripts_optional function, but then it is checked for having 'optional' value in call_scripts function

This is observed at least in up-to-date Ubuntu Xenial and Zesty
I will also check equivalent scripts in Debian testing/unstable and report my finding in a comment below.

[Wladimir Mutel (mwg)]

ok, I found that Debian hook-functions script does not have 'run_scripts_optional' function (in both 0.125 and 0.126 version of the package), so this is purely an Ubuntu problem.

[Wladimir Mutel (mwg)]

The fix is looking pretty simple, either compare the variable to "xy" string, or assign it "optional" instead of "y"

[Wladimir Mutel (mwg)]

Is this misbehaviour going to be perpetuated into Ubuntu Bionic 18.04 ?