Re: [PATCH v2] vfs: Tighten up linkat(..., AT_EMPTY_PATH)

From: Al Viro
Date: Sun Aug 25 2013 - 10:23:31 EST


On Sun, Aug 25, 2013 at 12:26:34AM -0700, Andy Lutomirski wrote:

> I think this is more screwed up than just flink and open. For example:
>
> $ echo 'WTF' >test
> $ truncate -s 1 /proc/self/fd/3 3<test
> $ cat test
> W$
>
> IMO that should have failed.

Why? truncate() always follows links, so what's the problem with that
one? That you get checks of truncate() and not ftruncate()?

> In an ideal world (I think) ffrob(N), frobat(N, "", AT_EMPTY_PATH),
> and frobat(AT_FDCWD, "/proc/self/fd/N) should generally do the same
> thing.

What about the cases where frob() and ffrob() check for different things?
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