Re: watch structure
On Tue, 2005-04-05 at 07:00 -0700, Casey Schaufler wrote:
--- Stephen Smalley <sds(a)tycho.nsa.gov> wrote:
> The structure could just define the length and perms
> fields, then put a
> char buf[0]; at the end to allow referencing of
> watch->buf, and just
> include the two strings immediately after the
> structure when creating
> it. Kernel can then extract them appropriately
> based on the lengths.
> No need to reserve fixed size fields for them.
That would require two copyins, one to get the
lengths and another to get the "buf". Not that
that's necessarily a stopper, but I had assumed
the goal was a one-shot interface.
No, the whole thing is sent as a single buffer that is copied into the
kernel once. buf[0] at the end of a structure is common practice to
reference data stuffed directly at the end of the structure.
--
Stephen Smalley <sds(a)tycho.nsa.gov>
National Security Agency