Why does Cygwin always use absolute paths instead of OBJECT_ATTRIBUTES.RootDirectory?

[Dan Shelton]

On Wed, 4 Feb 2026 at 22:37, Brian Inglis via Cygwin <cygwin@cygwin.com> wrote:
>
> On 2026-02-04 14:17, Dan Shelton via Cygwin wrote:
> > Why does Cygwin always use absolute paths instead of
> > OBJECT_ATTRIBUTES.RootDirectory in NtOpenFile(),
> > NtSetInformationFile() for rename and hardlinks
> >
> > This slows down Cygwin path lookups a lot, and with lots of path
> > elements each lookup with a relative RootDirectory might be a lot
> > faster, e.g. for openat(), linkat(), renameat().
>
> Because volunteers' spare time is limited, and performance is good enough for
> those who might do the work:

Please do not slap me. That hurt.

My question is about whether there are any technical issues which
prevent OBJECT_ATTRIBUTES.RootDirectory from being used in Cygwin for
openat().

2nd question: Is OBJECT_ATTRIBUTES.RootDirectory really a root, and
you cannot do cd ..?

Dan
-- 
Dan Shelton - Cluster Specialist Win/Lin/Bsd