Re: openat()

[Nicholas Miell <nmiell@comcast.net>]

On Wed, 2005-11-09 at 13:42 -0800, dean gaudet wrote:
> On Wed, 9 Nov 2005, Ulrich Drepper wrote:
> 
> > Can we please get the openat() syscall implemented?  I know Linus already
> > declared this is a good idea and I can only stress that it is really essential
> > for some things.  It is today impossible to write correct code which uses long
> > pathnames since all these operations would require the use of chdir() which
> > affect the whole POSIX process and not just one thread.  In addition we have
> > the reduction of race conditions.
> 
> oh sweet i've always wanted this for perf improvements in multithreaded 
> programs which have to deal with lots of lookups deep in a directory tree 
> (especially over NFS).
> 
> would this include other related syscalls such as link, unlink, rename, 
> chown, chmod... so that the the virtualization of the "current working 
> directory" concept is more complete?
> 
> -dean

I think that the full suite of "pathname lookups relative to a fd"
functions was implied.

Note that you could always introduce pthread_attr_setsharedfs(3) and
pthread_attr_getsharedfs(3) (or whatever you want to call them) which
control the passing of CLONE_FS to clone(2) in pthread_create(). This
would allow you to create threads which have their own pwd and umask
(and even chroot, but I don't think that would be very useful) without
any kernel changes.

-- 
Nicholas Miell <nmiell@comcast.net>