UUID_CLEAR(3UUID) Universally Unique Identifier Library Functions


NAME


uuid_clear, uuid_compare, uuid_copy, uuid_generate, uuid_generate_random,
uuid_generate_time, uuid_is_null, uuid_parse, uuid_time, uuid_unparse,
uuid_unparse_lower, uuid_unparse_upper - universally unique identifier
(UUID) operations

SYNOPSIS


cc [ flag ... ] file... -luuid [ library ... ]
#include <uuid/uuid.h>

void uuid_clear(uuid_t uu);


int uuid_compare(uuid_t uu1, uuid_t uu2);


void uuid_copy(uuid_t dst, uuid_t src);


void uuid_generate(uuid_t out);


void uuid_generate_random(uuid_t out);


void uuid_generate_time(uuid_t out);


int uuid_is_null(uuid_t uu);


int uuid_parse(char *in, uuid_t uu);


time_t uuid_time(uuid_t uu, struct timeval *ret_tv);


void uuid_unparse(uuid_t uu, char *out);


void uuid_unparse_lower(uuid_t uu, char *out);


void uuid_unparse_upper(uuid_t uu, char *out);


DESCRIPTION


The uuid_clear() function sets the value of the specified universally
unique identifier (UUID) variable uu to the NULL value.


The uuid_compare() function compares the two specified UUID variables uu1
and uu2 to each other. It returns an integer less than, equal to, or
greater than zero if uu1 is found to be, respectively, lexicographically
less than, equal, or greater than uu2.


The uuid_copy() function copies the UUID variable src to dst.


The uuid_generate() function creates a new UUID that is generated based
on high-quality randomness from /dev/urandom, if available. If
/dev/urandom is not available, uuid_generate() calls
uuid_generate_time(). Because the use of this algorithm provides
information about when and where the UUID was generated, it could cause
privacy problems for some applications.


The uuid_generate_random() function produces a UUID with a random or
pseudo-randomly generated time and Ethernet MAC address that corresponds
to a DCE version 4 UUID.


The uuid_generate_time() function uses the current time and the local
Ethernet MAC address (if available, otherwise a MAC address is
fabricated) that corresponds to a DCE version 1 UUID. If the UUID is not
guaranteed to be unique, the multicast bit is set (the high-order bit of
octet number 10).


The uuid_is_null() function compares the value of the specified UUID
variable uu to the NULL value. If the value is equal to the NULL UUID, 1
is returned. Otherwise 0 is returned.


The uuid_parse() function converts the UUID string specified by in to the
internal uuid_t format. The input UUID is a string of the form
cefa7a9c-1dd2-11b2-8350-880020adbeef. In printf(3C) format, the string is
"%08x-%04x-%04x-%04x-%012x", 36 bytes plus the trailing null character.
If the input string is parsed successfully, 0 is returned and the UUID is
stored in the location pointed to by uu. Otherwise -1 is returned.


The uuid_time() function extracts the time at which the specified UUID uu
was created. Since the UUID creation time is encoded within the UUID,
this function can reasonably be expected to extract the creation time
only for UUIDs created with the uuid_generate_time() function. The time
at which the UUID was created, in seconds since January 1, 1970 GMT (the
epoch), is returned (see time(2)). The time at which the UUID was
created, in seconds and microseconds since the epoch is also stored in
the location pointed to by ret_tv (see gettimeofday(3C)).


The uuid_unparse() and uuid_unparse_lower() functions convert the
specified UUID uu from the internal binary format to a lower case string
of the length defined in the uuid.h macro, UUID_PRINTABLE_STRING_LENGTH,
which includes the trailing null character. The resulting value is
stored in the character string pointed to by out.


The uuid_unparse_upper() function converts the specified UUID uu from the
internal binary format to a upper case string of the length defined in
the uuid.h macro, UUID_PRINTABLE_STRING_LENGTH, which includes the
trailing null character. The resulting value is stored in the character
string pointed to by out.

ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+

SEE ALSO


inetd(1M), time(2), gettimeofday(3C), libuuid(3LIB), printf(3C),
attributes(5)


April 9, 2014 UUID_CLEAR(3UUID)