Re: *at syscalls for xattrs?

[Jeff Garzik]

H. Peter Anvin wrote:
> Miklos Szeredi wrote:
> > The *at() thing basically gives you the advantages of a CWD without
> > the disadvantages.
> >
> > For example it could be useful to implement the functionality of
> > find(1) as a library interface.
>
> What the *at() interfaces really do is fix/paper over a longstanding
> wart in Unix: the cwd really should have been a standard file descriptor
> (like stdin/stdout/stderr) instead of a magic piece of state maintained
> in kernel space.

It's more than a wart, IMO.  *at() allows one to close races (with 
potential security implications) that are otherwise impossible to close, 
in directory traversal.

*at() permits a userspace program to hold proper references to all 
objects during a directory traversal, with all that implies.

	Jeff



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