This is about values like 0755 or 0664 which are used for file permissions. When using DIR_PERM=0755 then env() will convert this to int(755) but the correct value should have been int(493).

php > var_dump( ctype_digit( '0755' ) );
bool(true)
php > var_dump( (int) '0755' );
int(755)
php > var_dump( (int) 0755 );
int(493)

To support this a self::CONVERT_OCTAL option is probably needed which can be used to run before the current integer conversion. https://www.php.net/manual/de/function.octdec.php#85170 might be helpful.

Thoughts?