On Tue, 2012-10-30 at 00:48 -0400, Theodore Ts'o wrote:
> On Tue, Oct 30, 2012 at 09:49:58AM +0800, Huang Ying wrote:
> > The uuid_le/be_gen() in lib/uuid.c has set UUID variants to be DCE,
> > that is done in __uuid_gen_common() with "b[8] = (b[8] & 0x3F) | 0x80".
>
> Oh, I see, I missed that.
>
> > To deal with random number generation issue, how about use
> > get_random_bytes() in __uuid_gen_common()?
>
> We already have generate_random_uuid() in drivers/char/random.c, and
> no users for lib/uuid.c's equivalent uuid_be_gen(). So here's a
> counter-proposal, why don't we drop lib/uuid.c, and include in
> drivers/char/random.c:
>
> /*
> * Generate random GUID
> *
> * GUID's is like UUID's, but they uses the non-standard little-endian
> * layout, compared to what is defined in RFC-4112; it is primarily
> * used by the EFI specification.
> */
> void generate_random_guid(unsigned char uuid_out[16])
> {
> get_random_bytes(uuid_out, 16);
> /* Set UUID version to 4 --- truly random generation */
> uuid_out[7] = (uuid_out[7] & 0x0F) | 0x40;
> /* Set the UUID variant to DCE */
> uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80;
> }
> EXPORT_SYMBOL(generate_random_guid);
>
> I really don't think it's worth it to have a __uuid_gen_common once we
> are using get_random_bytes(), since there isn't much code to be
> factored out, and it's simpler just to have two functions in one place.
The intention of lib/uuid.c is to unify various UUID related code, and
put them in same place. In addition to UUID generation, it provide some
other utility and may provide/collect more in the future. So do you
think it is a good idea to put generate_rand_uuid/guid into lib/uuid.c
and maybe change the name/prototype to make it consistent with other
uuid definitions?
> Using UUID vs. GUID I think makes things much clearer, since the EFI
> specification talks about GUID's, not UUID's, and that way we don't
> have to worry about people getting confused about whether they should
> be using the little-endian versus big-endian variant. (And I'd love
> to ask to whoever wrote the EFI specification what on *Earth* were
> they thinking when they decided to diverge from the rest of the
> world....)
I think that is a good idea. From Wikipedia, GUID is in native byte
order, while UUID is in internet byte order.
Best Regards,
Huang Ying
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
