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

Jakob Bohm via Cygwin <[email protected]>
Newsgroups gmane.os.cygwin
Organization WiseMo A/S
Message-ID <[email protected]>
On 04/02/2026 23:50, Dan Shelton via Cygwin wrote:
> On Wed, 4 Feb 2026 at 22:37, Brian Inglis via Cygwin <[email protected]> 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 ..?
>
Take a look at the openat(3P) function, it seems to be what you are 
looking for.

Enjoy

Jakob
-- 
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded


-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple
lmpx.com only provides a reader for public news (NNTP) servers. It is not affiliated with the servers or forums shown here and is not responsible for the content of articles, which is written by their respective authors.