1130b656e5
This will make a number of things easier in the future, as well as (finally!) avoiding the Id-smashing problem which has plagued developers for so long. Boy, I'm glad we're not using sup anymore. This update would have been insane otherwise.
111 lines
3.0 KiB
Groff
111 lines
3.0 KiB
Groff
.\"
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.\" Copyright (c) 1995 David Hovemeyer <daveho@infocom.com>
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.\"
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 DEVELOPERS 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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.\" $FreeBSD$
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.\"
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.Dd August 2, 1995
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.Dt SHMAT 2
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.Os FreeBSD
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.Sh NAME
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.Nm shmat ,
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.Nm shmdt
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.Nd attach or detach shared memory
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.Sh SYNOPSIS
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.Fd #include <sys/types.h>
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.Fd #include <sys/ipc.h>
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.Fd #include <sys/shm.h>
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.Ft void *
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.Fn "shmat" "int shmid" "void *addr" "int flag"
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.Ft int
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.Fn "shmdt" "void *addr"
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.Sh DESCRIPTION
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.Fn Shmat
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attaches the shared memory segment identified by
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.Fa shmid
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to the calling process's address space. The address where the segment
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is attached is determined as follows:
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.\"
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.\" These are cribbed almost exactly from Stevens, _Advanced Programming in
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.\" the UNIX Environment_.
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.\"
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.Bl -bullet
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.It
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If
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.Fa addr
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is 0, the segment is attached at an address selected by the
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kernel.
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.It
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If
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.Fa addr
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is nonzero and SHM_RND is not specified in
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.Fa flag ,
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the segment is attached the specified address.
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.It
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If
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.Fa addr
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is specified and SHM_RND is specified,
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.Fa addr
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is rounded down to the nearest multiple of SHMLBA.
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.El
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.Pp
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.Fn Shmdt
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detaches the shared memory segment at the address specified by
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.Fa addr
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from the calling process's address space.
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.Sh RETURN VALUES
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Upon success,
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.Fn shmat
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returns the address where the segment is attached; otherwise, -1
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is returned and
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.Va errno
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is set to indicate the error.
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.Pp
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Upon success,
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.Fn shmdt
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returns 0; otherwise, -1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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.Fn Shmat
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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No shared memory segment was found corresponding to
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.Fa shmid .
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.It Bq Er EINVAL
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.Fa addr
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was not an acceptable address.
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.El
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.Pp
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.Fn Shmdt
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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.Fa addr
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does not point to a shared memory segment.
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.Sh "SEE ALSO"
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.Xr shmget 2 ,
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.Xr shmctl 2
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