[U-Boot] [PATCH v4 3/6] lib: uuid: add functions to generate UUID version 4

[Stephen Warren]

On 03/19/2014 11:58 AM, Przemyslaw Marczak wrote:
> This patch adds support to generate UUID (Universally Unique Identifier)
> in version 4 based on RFC4122, which is randomly.
> 
> Source: https://www.ietf.org/rfc/rfc4122.txt

Some nits in the comments below, but otherwise:
Acked-by: Stephen Warren <swarren at nvidia.com>

> diff --git a/include/uuid.h b/include/uuid.h

> +/* This is structure is in big-endian */
> +struct uuid {

Not any more; with the introduction of enum uuid_str_t, some of the
fields could be either LE or BE. I would say "See the comment near the
top of lib/uuid.c for details of the endianness of fields in this struct".

> diff --git a/lib/uuid.c b/lib/uuid.c

>  /*
>   * UUID - Universally Unique IDentifier - 128 bits unique number.
>   *        There are 5 versions and one variant of UUID defined by RFC4122
> - *        specification. Depends on version uuid number base on a time,
> - *        host name, MAC address or random data.
> + *        specification. Depends on version uuid number base on:

I still have no idea what "Depends on version uuid number base on" means.

> + *        - time, MAC address(v1),
> + *        - user ID(v2),
> + *        - MD5 of name or URL(v3),
> + *        - random data(v4),
> + *        - SHA-1 of name or URL(v5),
> + *
> + * This library implements UUID v4.

I think that should say "gen_rand_uuid()" not "This library", since the
source of the data in the UUID fields only matters when creating the
UUID, not when performing str<->bin conversion.

> + *
> + * Layout of UUID Version 4:
> + * timestamp - 60-bit: time_low, time_mid, time_hi_and_version
> + * version   - 4 bit (bit 4 through 7 of the time_hi_and_version)
> + * clock seq - 14 bit: clock_seq_hi_and_reserved, clock_seq_low
> + * variant:  - bit 6 and 7 of clock_seq_hi_and_reserved
> + * node      - 48 bit
> + * In this version all fields beside 4 bit version are randomly generated.
> + * source: https://www.ietf.org/rfc/rfc4122.txt

gen_rand_uuid() doesn't actually honor that format; it creates pure
random data rather than filling in any timestamps, clock sequence data, etc.