Messages in this thread | | | Date | Fri, 25 Sep 2009 10:53:16 -0600 | From | Andreas Dilger <> | Subject | Re: [PATCH] vfs: new O_NODE open flag |
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On Sep 25, 2009 13:37 +0100, Dr. David Alan Gilbert wrote: > * Miklos Szeredi (miklos@szeredi.hu) wrote: > > On Fri, 25 Sep 2009, Andreas Gruenbacher wrote: > > > On Thursday, 24 September 2009 16:51:58 Miklos Szeredi wrote: > > > > This patch adds a new open flag, O_NODE. This flag means: open just > > > > the filesystem node instead of the object referenced by the node. > > > > > > What is the intended use for O_NODE? > > > > It lets userspace file descriptors reference a inode without actually > > "dereferencing" it to get the underlying object. This allows for a > > couple of new things: > > > > - opening a special file (device/socket/fifo) without side effects > > > > - opening a symlink > > > > - opening any type of file without any permission is also possible > > (of course the resuling file descriptor may not be read or written) > > > > The above allows fstat(), fchmod(), ioctl(), etc to be used for files > > previously not possible. > > Given an fd opened in this way is it possible to reopen it normally and > be guarenteed to get the same object?
That was something I'd be interested in as well.
Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.
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