From: Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: openat(2) is mostly useless, sadly
To: "Theo de Raadt" <deraadt@openbsd.org>
Cc: h@hartzer.sh, tech@openbsd.org
Date: Sat, 31 May 2025 16:56:15 +0200

> From: "Theo de Raadt" <deraadt@openbsd.org>
> Date: Fri, 30 May 2025 19:17:46 -0600
> 
> Steffen Nurpmeso <steffen@sdaoden.eu> wrote:
> 
> > I would not use ENOTTY for F_BELOW on !DIR, maybe ENOTDIR is
> > better.
> 
> >From errno(2) manpage:
> 
>      20 ENOTDIR Not a directory. A component of the specified pathname
>              existed, but it was not a directory, when a directory was
>              expected.
> 
> F_BELOW is fcntl(2).
> 
>      int
>      fcntl(int fd, int cmd, ...);
> 
> But there is no pathname.  Yes it is partly vague, but then grep the whole
> tree for ENOTDIR and always anticipates a pathname at a higher level.

Note that openat(2) says:

[ENOTDIR]          The path argument specifies a relative path and the fd
                   argument is a valid file descriptor but it does not
		   reference a directory.

So here ENOTDIR does apply to a file descriptor.