getFilenameFromMainDir() triggers PHP Warnings open_basedir
core: Core: Error handler (BE): PHP Warning: is_file(): open_basedir restriction in effect. File(/var/www/website/htdocs/../typo3conf/ext/extension/Resources/Public/file) is not within the allowed path(s):
when the BE is browsed.
This happens because "is_file($absolutePath)" checks outside the website root in the case of a passed file that has a relative path that begins with "../typo3conf/extension..." and open_basedir doesn't allow it.
Me and Markus Klein talked about the problem and decided to use the PHP error control operator @ to suppress the warnings because other solutions could break the code in other cases.