2fe8fb192f
There is important information about booting non-ack images in docs/UPDATING. ack/aout-format images can't be built any more, and booting clang/ELF-format ones is a little different. Updating to the new boot monitor is recommended. Changes in this commit: . drop boot monitor -> allowing dropping ack support . facility to copy ELF boot files to /boot so that old boot monitor can still boot fairly easily, see UPDATING . no more ack-format libraries -> single-case libraries . some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases . drop several ack toolchain commands, but not all support commands (e.g. aal is gone but acksize is not yet). . a few libc files moved to netbsd libc dir . new /bin/date as minix date used code in libc/ . test compile fix . harmonize includes . /usr/lib is no longer special: without ack, /usr/lib plays no kind of special bootstrapping role any more and bootstrapping is done exclusively through packages, so releases depend even less on the state of the machine making them now. . rename nbsd_lib* to lib* . reduce mtree
148 lines
5.2 KiB
Groff
148 lines
5.2 KiB
Groff
.\" $NetBSD: uuidgen.2,v 1.4 2005/01/30 18:13:04 jwise Exp $
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.\" $FreeBSD: src/lib/libc/sys/uuidgen.2,v 1.7 2003/06/27 13:41:29 yar Exp $
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.\" Copyright (c) 2002 Marcel Moolenaar
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD: src/lib/libc/sys/uuidgen.2,v 1.7 2003/06/27 13:41:29 yar Exp $
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.\"
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.Dd May 26, 2002
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.Dt UUIDGEN 2
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.Os
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.Sh NAME
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.Nm uuidgen
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.Nd generate universally unique identifiers
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/uuid.h
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.Ft int
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.Fn uuidgen "struct uuid *store" "int count"
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.Sh DESCRIPTION
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The
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.Fn uuidgen
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system call generates
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.Fa count
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universally unique identifiers (UUIDs) and writes them to the buffer
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pointed to by
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.Fa store .
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The identifiers are generated according to the syntax and semantics of the
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DCE version 1 variant of universally unique identifiers.
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See below for a more in-depth description of the identifiers.
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When no IEEE 802
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address is available for the node field, a random multi-cast address is
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generated for each invocation of the system call.
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According to the algorithm of generating time-based UUIDs, this will also
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force a new random clock sequence, thereby increasing the likelihood for
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the identifier to be unique.
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.Pp
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When multiple identifiers are to be generated, the
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.Fn uuidgen
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system call will generate a set of identifiers that is dense in such a way
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that there is no identifier that is larger than the smallest identifier in the
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set and smaller than the largest identifier in the set and that is not already
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in the set.
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.Pp
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Universally unique identifiers, also known as globally unique identifiers
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(GUIDs), have a binary representation of 128-bits.
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The grouping and meaning of these bits is described by the following
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structure and its description of the fields that follow it:
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.Bd -literal
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struct uuid {
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uint32_t time_low;
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uint16_t time_mid;
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uint16_t time_hi_and_version;
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uint8_t clock_seq_hi_and_reserved;
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uint8_t clock_seq_low;
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uint8_t node[_UUID_NODE_LEN];
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};
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.Ed
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.Bl -tag -width ".Va clock_seq_hi_and_reserved"
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.It Va time_low
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The least significant 32 bits of a 60-bit timestamp.
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This field is stored in the native byte-order.
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.It Va time_mid
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The least significant 16 bits of the most significant 28 bits of the 60-bit
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timestamp.
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This field is stored in the native byte-order.
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.It Va time_hi_and_version
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The most significant 12 bits of the 60-bit timestamp multiplexed with a 4-bit
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version number.
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The version number is stored in the most significant 4 bits of the 16-bit
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field.
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This field is stored in the native byte-order.
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.It Va clock_seq_hi_and_reserved
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The most significant 6 bits of a 14-bit sequence number multiplexed with a
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2-bit variant value.
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Note that the width of the variant value is determined by the variant itself.
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Identifiers generated by the
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.Fn uuidgen
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system call have variant value 10b.
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the variant value is stored in the most significant bits of the field.
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.It Va clock_seq_low
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The least significant 8 bits of a 14-bit sequence number.
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.It Va node
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The 6-byte IEEE 802 (MAC) address of one of the interfaces of the node.
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If no such interface exists, a random multi-cast address is used instead.
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.El
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.Pp
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The binary representation is sensitive to byte ordering.
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Any multi-byte field is to be stored in the local or native byte-order and
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identifiers must be converted when transmitted to hosts that do not agree
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on the byte-order.
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The specification does not however document what this means in concrete
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terms and is otherwise beyond the scope of this system call.
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
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The
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.Fn uuidgen
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system call can fail with:
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The buffer pointed to by
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.Fa store
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could not be written to for any or all identifiers.
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.It Bq Er EINVAL
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The
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.Fa count
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argument is less than 1 or larger than the hard upper limit of 2048.
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.El
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.Sh SEE ALSO
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.Xr uuidgen 1 ,
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.Xr uuid 3
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.Sh STANDARDS
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The identifiers are represented and generated in conformance with the DCE 1.1
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RPC specification.
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The
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.Fn uuidgen
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system call is itself not part of the specification.
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.Sh HISTORY
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The
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.Fn uuidgen
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system call first appeared in
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.Fx 5.0
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and was subsequently added to
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.Nx 2.0 .
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