Lua HTTP interface killed by link circles

Steps to reproduce

Open the preferences dialog, switch from Simple to All settings, Navigate to Interface / Main interfaces / Lua.

In the Lua HTTP panel, set Source directory to some directory you have write permissions to. For example, /home/john/Videos and make sure the Directory index checkbox is checked.

In a sub-directory of that directory, create a circular symbolic link. For example:

$ cd /home/john/Videos
$ mkdir dir-with-circle
$ cd dir-with-circle
$ ln -s ../dir-with-circle cilcular-link-2

Now start vlc with http:

$ vlc -extraintf=http --http-host 0.0.0.0 --http-port 8081

The result is an error message:

[0000560c57902610] [http] lua interface error: Error loading script /usr/lib/x86_64-linux-gnu/vlc/lua/intf/http.lua: /usr/lib/x86_64-linux-gnu/vlc/lua/intf/http.lua:304: attempt to index local 's' (a nil value)

Port 8081 is not opened, as can be verified using

$ lsof -i4 -n | grep LISTEN

Adding a print statement before the offending line tells the whole story:

if s == nil then print("===> s is nil; dir: " .. dir .. "; f: " .. f) end

which prints, just before the error message:

===> s is nil; dir: /home/john/Videos/dir-with-circle/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2/cilcular-link-2; f: cilcular-link-2

Suggested fix

A patch against this is trivial: just change "if s.type == ..." to "if s ~= nil and s.type == ..." on line 301 (or a few lines below - it depends on the vlc version), and then again on (or a bit after) line 316.

A better fix would be to add a check against circles (skipping symbolic links altogether would break some very useful use cases).