Re: [PATCH] utimensat() non-conformances and fixes [v3]

[Jamie Lokier]

Al Viro wrote:
> On Tue, Jun 03, 2008 at 01:01:35PM +0100, Jamie Lokier wrote:
> > > with a lot of things, starting with "why utimes(2) has weaker requirements
> > > with NULL argument", but we are far too late to fix that.
> > 
> > To be fair, having a writable file descriptor only lets you change the
> > mtime to "now", and having a readable file descriptor only lets you
> > change the atime to "now".
> > 
> > Changing the times _in general_ can be seen as over-reaching those
> > capabilities and arguably justifies more strict checks.
> 
> Which is what all questions about writability apply only to NULL case
> anyway...

Oh!

So if I have the file descriptor, I can just as well change the mtime
by read a byte and write it back.  Or even do a zero-length write, on
some OSes.

-- Jamie
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/