.\"	$OpenBSD: uuid_compare.3,v 1.2 2020/11/14 10:35:58 jmc Exp $
.\"	$NetBSD: uuid.3,v 1.7 2008/05/02 18:11:05 martin Exp $
.\"
.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jason R. Thorpe.
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.\" Copyright (c) 2002 Marcel Moolenaar
.\" Copyright (c) 2002 Hiten Mahesh Pandya
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.\" modification, are permitted provided that the following conditions
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.\" $FreeBSD: src/lib/libc/uuid/uuid.3,v 1.4 2003/08/08 19:12:28 marcel Exp $
.\"
.Dd $Mdocdate: November 14 2020 $
.Dt UUID_COMPARE 3
.Os
.Sh NAME
.Nm uuid_compare , uuid_create , uuid_create_nil , uuid_equal ,
.Nm uuid_from_string , uuid_hash , uuid_is_nil , uuid_to_string ,
.Nm uuid_enc_le , uuid_dec_le , uuid_enc_be , uuid_dec_be
.Nd Universally Unique Identifier routines
.Sh SYNOPSIS
.In uuid.h
.Ft int32_t
.Fn uuid_compare "const uuid_t *uuid1" "const uuid_t *uuid2" "uint32_t *status"
.Ft void
.Fn uuid_create "uuid_t *uuid" "uint32_t *status"
.Ft void
.Fn uuid_create_nil "uuid_t *uuid" "uint32_t *status"
.Ft int32_t
.Fn uuid_equal "const uuid_t *uuid1" "const uuid_t *uuid2" "uint32_t *status"
.Ft void
.Fn uuid_from_string "const char *str" "uuid_t *uuid" "uint32_t *status"
.Ft uint16_t
.Fn uuid_hash "const uuid_t *uuid" "uint32_t *status"
.Ft int32_t
.Fn uuid_is_nil "const uuid_t *uuid" "uint32_t *status"
.Ft void
.Fn uuid_to_string "const uuid_t *uuid" "char **str" "uint32_t *status"
.Ft void
.Fn uuid_enc_le "void *buf" "const uuid_t *uuid"
.Ft void
.Fn uuid_dec_le "const void *buf" "uuid_t *"
.Ft void
.Fn uuid_enc_be "void *buf" "const uuid_t *uuid"
.Ft void
.Fn uuid_dec_be "const void *buf" "uuid_t *"
.Sh DESCRIPTION
These routines provide for the creation and manipulation of Universally
Unique Identifiers
.Pq UUIDs ,
also referred to as Globally Unique Identifiers
.Pq GUIDs .
.Pp
The
.Fn uuid_compare
function compares two UUIDs.
It returns \-1 if
.Fa uuid1
precedes
.Fa uuid2 ,
0 if they are equal, or 1 if
.Fa uuid1
follows
.Fa uuid2 .
.Pp
The
.Fn uuid_create
function creates a new UUID.
Storage for the new UUID must be pre-allocated by the caller.
.Pp
The
.Fn uuid_create_nil
function creates a nil-valued UUID.
Storage for the new UUID must be pre-allocated by the caller.
.Pp
The
.Fn uuid_equal
function compares two UUIDs to determine if they are equal.
It returns 1 if they are equal, and 0 if they are not equal.
.Pp
The
.Fn uuid_from_string
function parses a 36-character string representation of a UUID and
converts it to binary representation.
Storage for the UUID must be pre-allocated by the caller.
.Pp
The
.Fn uuid_hash
function generates a hash value for the specified UUID.
Note that the hash value is not a cryptographic hash, and should not be
assumed to be unique given two different UUIDs.
.Pp
The
.Fn uuid_is_nil
function returns 1 if the UUID is nil-valued and 0 if it is not.
.Pp
The
.Fn uuid_to_string
function converts a UUID from binary representation to string representation.
Storage for the string is dynamically allocated and returned via the
.Fa str
argument.
This pointer should be passed to
.Xr free 3
to release the allocated storage when it is no longer needed.
.Pp
The
.Fn uuid_enc_le
and
.Fn uuid_enc_be
functions encode a binary representation of a UUID into an octet stream
in little-endian and big-endian byte order, respectively.
The destination buffer must be pre-allocated by the caller, and must be
large enough to hold the 16-octet binary UUID.
.Pp
The
.Fn uuid_dec_le
and
.Fn uuid_dec_be
functions decode a UUID from an octet stream in little-endian and
big-endian byte order, respectively.
.Sh RETURN VALUES
The
.Fn uuid_compare ,
.Fn uuid_create ,
.Fn uuid_create_nil ,
.Fn uuid_equal ,
.Fn uuid_from_string ,
.Fn uuid_hash ,
.Fn uuid_is_nil ,
and
.Fn uuid_to_string
functions return successful or unsuccessful completion status in the
.Fa status
argument unless it is
.Dv NULL .
Possible values are:
.Bl -tag -width "uuid_s_invalid_string_uuid"
.It Dv uuid_s_ok
The function completed successfully.
.It Dv uuid_s_bad_version
The UUID does not have a known version.
.It Dv uuid_s_invalid_string_uuid
The string representation of a UUID is not valid.
.It Dv uuid_s_no_memory
Memory could not be allocated for the operation.
.El
.\" .Sh SEE ALSO
.\" .Xr uuidgen 1
.Sh STANDARDS
The
.Fn uuid_compare ,
.Fn uuid_create ,
.Fn uuid_create_nil ,
.Fn uuid_equal ,
.Fn uuid_from_string ,
.Fn uuid_hash ,
.Fn uuid_is_nil ,
and
.Fn uuid_to_string
functions are compatible with the DCE 1.1 RPC specification.
.Pp
.Fn uuid_create
generates version 4 UUIDs,
specified by section 4.4 of RFC 4122.