At the moment, the only pre-open support we have is the file system
itself (root a.k.a. / or file-descriptor 3). We may in the future add
the ability to pre-open sockets, but in any case, this is where we are
today.
This change hardens logic around fd_preXXX functions, ensuring they only
work on actual pre-opens. This also fixes the path returned in filestat
as we sometimes returned a full path, when typically the basename is the
only part that can be returned.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
`os.DirFS` ironically doesn't implement `fs.ReadDirFS`, so we cannot
open a directory this way. This blindly attempts to open "." regardless
of if the `fs.FS` implementation is a `fs.ReadDirFS` or not, and if
successful, enforces that the file returned is a directory. If not, a
fake directory is returned.
Doing so allows real stat to be returned for root, and also a chance to
know if a filesystem configured is real or not. Later, we'll need this
to implement open flags.
Signed-off-by: Adrian Cole <adrian@tetrate.io>
