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lib: uuid: add functions to generate UUID version 4

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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

Changes:
- new configs:
  - CONFIG_LIB_UUID for compile lib/uuid.c
  - CONFIG_RANDOM_UUID for functions gen_rand_uuid() and gen_rand_uuid_str()
- add configs dependency to include/config_fallbacks.h for lib uuid.

lib/uuid.c:
- add gen_rand_uuid() - this function writes 16 bytes len binary representation
  of UUID v4 to the memory at given address.

- add gen_rand_uuid_str() - this function writes 37 bytes len hexadecimal
  ASCII string representation of UUID v4 to the memory at given address.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Lukasz Majewski <l.majewski@samsung.com>
[trini: Add CONFIG_EFI_PARTITION to fallbacks]
Signed-off-by: Tom Rini <trini@ti.com>
This commit is contained in:
Przemyslaw Marczak 2014-04-02 10:20:04 +02:00 • committed by Tom Rini
parent d718ded056
commit 4e4815feae
4 changed files with 100 additions and 5 deletions
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66
lib/uuid.c
View file

@ -14,8 +14,22 @@
/*
* 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. A UUID contains a set of fields. The set varies
* depending on the version of the UUID, as shown below:
* - time, MAC address(v1),
* - user ID(v2),
* - MD5 of name or URL(v3),
* - random data(v4),
* - SHA-1 of name or URL(v5),
*
* Layout of UUID:
* 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
*
* source: https://www.ietf.org/rfc/rfc4122.txt
*
* UUID binary format (16 bytes):
*
@ -149,3 +163,51 @@ void uuid_bin_to_str(unsigned char *uuid_bin, char *uuid_str, int str_format)
}
}
}
/*
* gen_rand_uuid() - this function generates a random binary UUID version 4.
* In this version all fields beside 4 bits of version and
* 2 bits of variant are randomly generated.
*
* @param uuid_bin - pointer to allocated array [16B]. Output is in big endian.
*/
#ifdef CONFIG_RANDOM_UUID
void gen_rand_uuid(unsigned char *uuid_bin)
{
struct uuid uuid;
unsigned int *ptr = (unsigned int *)&uuid;
int i;
/* Set all fields randomly */
for (i = 0; i < sizeof(struct uuid) / sizeof(*ptr); i++)
*(ptr + i) = cpu_to_be32(rand());
clrsetbits_be16(&uuid.time_hi_and_version,
UUID_VERSION_MASK,
UUID_VERSION << UUID_VERSION_SHIFT);
clrsetbits_8(&uuid.clock_seq_hi_and_reserved,
UUID_VARIANT_MASK,
UUID_VARIANT << UUID_VARIANT_SHIFT);
memcpy(uuid_bin, &uuid, sizeof(struct uuid));
}
/*
* gen_rand_uuid_str() - this function generates UUID v4 (random) in two string
* formats UUID or GUID.
*
* @param uuid_str - pointer to allocated array [37B].
* @param - uuid output type: UUID - 0, GUID - 1
*/
void gen_rand_uuid_str(char *uuid_str, int str_format)
{
unsigned char uuid_bin[UUID_BIN_LEN];
/* Generate UUID (big endian) */
gen_rand_uuid(uuid_bin);
/* Convert UUID bin to UUID or GUID formated STRING */
uuid_bin_to_str(uuid_bin, uuid_str, str_format);
}
#endif