UUID_CLEAR(3UUID)UUID_CLEAR(3UUID)NAME
uuid_clear, uuid_compare, uuid_copy, uuid_generate, uuid_generate_ran‐
dom, 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, lexicographi‐
cally 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_gener‐
ate_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 corre‐
sponds 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 fabri‐
cated) 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 charac‐
ter. 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 spec‐
ified 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 ALSOinetd(1M), time(2), gettimeofday(3C), libuuid(3LIB), printf(3C),
attributes(5)
Apr 9, 2014 UUID_CLEAR(3UUID)
