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
4.1 KiB
Groff
148 lines
4.1 KiB
Groff
.\" $NetBSD: randomid.3,v 1.7 2006/01/05 19:45:29 rpaulo Exp $
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.\"
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.\" Copyright (C) 2006 The NetBSD Foundation
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.\" All rights reserved.
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.\"
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.\" Copyright (C) 2003 WIDE Project.
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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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.\" 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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.\" 3. Neither the name of the project nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd January 5, 2006
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.Dt RANDOMID 3
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.Os
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.Sh NAME
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.Nm randomid
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.Nm randomid_new ,
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.Nm randomid_delete ,
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.Nd provide pseudo-random data stream without repetitions
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.Sh SYNOPSIS
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.In sys/types.h
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.In randomid.h
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.Ft uint32_t
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.Fn randomid "randomid_t ctx"
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.Ft randomid_t
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.Fn randomid_new "int bits" "long timeo"
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.Ft void
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.Fn randomid_delete "randomid_t ctx"
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.Sh DESCRIPTION
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The
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.Fn randomid
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function provides pseudo-random data stream,
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which is guaranteed not to generate the same number twice during
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a certain duration.
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.Fa ctx
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is the context which holds internal state for the random number generator.
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.Pp
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To initialize a context,
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.Fa randomid_new
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is used.
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.Fa bits
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specifies the bitwidth of the value generated by
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.Fn randomid .
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Currently 32, 20, and 16 are supported.
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.Fa timeo
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specifies the reinitialization interval in seconds.
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.Fa timeo
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has to be bigger than
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.Dv RANDOMID_TIMEO_MIN .
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.Fa randomid_new
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returns a dynamically-allocated memory region allocated by
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.Xr malloc 3 .
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.Pp
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.Fn randomid_delete
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will
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.Xr free 3
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the internal state
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.Fa ctx .
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.Pp
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The same number may appear after two reinitialization events of the internal state,
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.Fa ctx .
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Reinitialization happens when the random number generator cycle is exhausted,
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or
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.Fa timeo
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seconds have passed since the last reinitialization.
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For instance,
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.Fa ctx
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configured to generate 16 bit data stream will reinitialize its internal state
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every 30000 calls to
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.Fn randomid
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.Po
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or after
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.Fa timeo
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seconds
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.Pc ,
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therefore the same data will not appear until after 30000 calls to
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.Fn randomid
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.Po
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or after
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.Fa timeo
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seconds
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.Pc .
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.Pp
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The internal state,
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.Fa ctx ,
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determines the data stream generated by
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.Fn randomid .
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.Fa ctx
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must be allocated per data stream
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.Pq such as a specific data field .
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It must not be shared among multiple data streams with different usage.
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.\"
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.Sh EXAMPLES
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.Bd -literal -offset indent
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#include \*[Lt]stdio.h\*[Gt]
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#include \*[Lt]sys/types.h\*[Gt]
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#include \*[Lt]randomid.h\*[Gt]
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uint32_t
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genid(void)
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{
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static randomid_t ctx = NULL;
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if (!ctx)
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ctx = randomid_new(16, (long)3600);
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return randomid(ctx);
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}
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.Ed
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.\"
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.Sh ERRORS
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.Fn randomid_new
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returns
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.Dv NULL
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on error and sets the external variable
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.Va errno .
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.\"
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.Sh SEE ALSO
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.Xr arc4random 3
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.\"
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.Sh HISTORY
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The pseudo-random data stream generator was designed by Niels Provos for
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.Ox
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IPv4 fragment ID generation.
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.Fn randomid
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is a generalized version of the generator, reworked by Jun-ichiro itojun Hagino,
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and was introduced in
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.Nx 2.0 .
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