This wonderfully large commit replaces basically everything under the
`server/filesystem` package, re-implementing essentially everything.
This is related to
https://github.com/pterodactyl/wings/security/advisories/GHSA-494h-9924-xww9
If any vulnerabilities related to symlinks persist after this commit, I
will be very upset.
Signed-off-by: Matthew Penner <me@matthewp.io>
This function was not actually safe in theory. If an unknown stat source was passed in it would be possible for a symlinked file to not be detected as a symlink, thus skipping any safe path resolutions.
This would happen if the stat source was a regular os.Stat call and not an os.Lstat call, but since there is no way to differentiate between those two in the code, it is safer to just manually apply this logic in the positions where we _know_ for certain that we're working with the results of an Lstat call.
