stubby: ensure appdata directory is present on service start

[totkeks]

Maintainer: unknown
Compile tested: no
Run tested: manually added to the /etc/init.d/stubby on OpenWrt SNAPSHOT r28091-77cfe8fd15

fixes #25431

[hnyman]

I think that you should set some default there in case the option is not there.
Now you just accept even an empty string as dir and start doing mkdir, chown, whatever...

Some verification of the string , check for not-empty value before doing mkdir ?
And possibly chosen only if mkdir succeeded.

Providing a fall-back default value would also be good.

[totkeks]

I think that you should set some default there in case the option is not there. Now you just accept even an empty string as dir and start doing mkdir, chown, whatever...

Some verification of the string , check for not-empty value before doing mkdir ? And possibly chosen only if mkdir succeeded.

Providing a fall-back default value would also be good.

Thanks for the feedback!
I thought about this too, when looking at the init file.

When it builds the config from uci data, it assumes a hardcoded default value:

config_get appdata_dir "global" appdata_dir "/var/lib/stubby"

And I assumed that this would apply to my changes as well. But it doesn't because the default value only applies to the .yml config and not the uci config.

So, I replaced that with a global variable in the script and reused it for my added code block. Also added checks on the string and checked for success of mkdir.

On the other hand, it is very odd that stubby doesn't throw any errors or even warnings when the directory is not available or it has insufficient permissions. But that is an upstream issue and the package hasn't had an update in the last years. I'm surprised no one reported the issue I had before.

[totkeks]

Is there anything else I need to do, before this PR could be approved?