On Fri, Jul 12, 2013 at 12:39 PM, Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote:
>
> I mean something like this:
>
> Safer ABI for O_TMPFILE
>
> [suggested by Rasmus Villemoes] make O_DIRECTORY | O_RDWR part of O_TMPFILE;
> that will fail on old kernels in a lot more cases than what I came up with.
So see earlier about why I'm not convinced about O_RDWR. But even if
we really want that (and it might be better to start off too narrow
than accept anything else) your patch tests those bits the wrong way
(any O_RDWR test should be done using the O_ACCMODE mask, not using
the O_RDWR value itself as a mask)
Also, to make sure that the "no preexisting file" case fails, I still
think you should also verify that O_CREAT is not set. Otherwise
Rasmus' case
open("/tmp/test/link_to_nowhere", O_DIRECTORY | O_RDWR, 0666) ->
-1; No such file or directory
can work, and the case that rasmus didn't have at all (non-existent
pathname) also just silently succeeds by creating a file instead of
the expected directory..
So you could have something like
#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY | O_RDWR)
#define O_TMPFILE_MASK (__O_TMPFILE | O_DIRECTORY | O_CREAT | O_ACCMODE)
and then use
if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
return -ENOTSUPP;
or whatever.
Hmm?
Linus
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