Make it possible to resolve svg's outside \OC::$SERVERROOT

[kesselb]

Resolve update blocker for snap.

Is this pr backportable? Alternatively we could keep the current approach and add the patch as fallback.

[rullzer]

I don't get what this tries to solve...

[kesselb]

I don't get what this tries to solve...

Yes description is missing some details 🙈

This PR should fix a issue with resolving the path for svg files for app directories outside the document root. It's related to #13556 but not a fix for the ResourceLocator warning.

Here are the details: #13556 (comment)

I have no idea what the current approach should do. But substr($appRootPath, strlen($this->serverRoot)) will not work if the apps directories is not a children of the server root. This will probably break other things 🤷‍♂️

If this patch is accepted it's possible to return svg's also for apps not reachable from the web. That makes no sense but was forbidden before.

I think the actual issue is somewhere else: #13556 (comment) For whatever reason symlinks are resolved at some point (probably to make other features work) but that's the actual issue. Nextcloud should work with symlinks.

[pachulo]

Nextcloud should work with symlinks.

I think that this summarizes it quite well: for the snap to work OK, this is required.

Any news on this? Do you need more info @rullzer ?

[nickvergessen]

Didn't test but the change looks good and the unit tests should prove it

[MorrisJobke]

@kesselb Backport to stable18?

[kesselb]

I would prefer to not backport it ;)