*at family of syscalls in FreeBSD

[Roman Divacky]

On Tue, Jun 05, 2007 at 06:17:40PM -0700, Eric Lemar wrote:
> I'm definitely a fan of this API.  Aside from the general thread-related
> utility of this API, it provides a reasonable API for accessing
> windows-style ADS streams (subfiles) on a filesystem that supports them
> and is becoming reasonably cross-platform.  This lets you handle things
> like ADS hanging off directories in a comparatively sane manner.
> 
> We've actually implemented a subset of these syscalls in-house (Isilon)
> for use with our filesystem, largely for the ADS-related functionality.
> Generally speaking, in our tree most of the traditional non-'at' syscalls
> are just small kernel wrappers around the 'at' interfaces.  Overall ends
> up looking fairly clean and we've ended up using them even in places
> where we don't need the ADS functionality just because they are so
> convenient.
> 
> If you're interested in implementing this API I'd be happy to talk about
> our implementation and see whether the relevant parts of our implementation
> would be useful for the general community.

my current patch is at: www.vlakno.cz/~rdivacky/linux_at.patch

it does not implement the native fbsd syscalls, only the linuxulator ones
but adding those is a matter of minutes. I asked for a review by pjd and/or
rwatson and hopefully this will get commited soon..

roman