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
140 lines
4.1 KiB
Groff
140 lines
4.1 KiB
Groff
.\" $NetBSD: shmat.2,v 1.18 2010/03/22 19:30:55 joerg Exp $
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.\"
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.\" Copyright (c) 1995 Frank van der Linden
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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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed for the NetBSD Project
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.\" by Frank van der Linden
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.\" 4. The name of the author may not be used to endorse or promote products
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.\" derived from this software without specific prior written permission
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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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.Dd June 17, 2002
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.Dt SHMAT 2
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.Os
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.Sh NAME
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.Nm shmat ,
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.Nm shmdt
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.Nd map/unmap shared memory
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/shm.h
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.Ft void *
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.Fn shmat "int shmid" "const void *shmaddr" "int shmflg"
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.Ft int
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.Fn shmdt "const void *shmaddr"
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.Sh DESCRIPTION
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.Fn shmat
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maps the shared memory segment associated with the shared memory identifier
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.Fa shmid
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into the address space of the calling process.
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The address at which the segment is mapped is determined by the
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.Fa shmaddr
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parameter.
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If it is equal to 0, the system will pick an address itself.
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Otherwise, an attempt is made to map the shared memory segment at the
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address
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.Fa shmaddr
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specifies.
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If
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.Dv SHM_RND
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is set in
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.Fa shmflg ,
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the system will round the address down to a multiple of
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.Dv SHMLBA
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bytes
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.Pf ( Dv SHMLBA
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is defined in
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.In sys/shm.h ) .
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.Pp
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A shared memory segment can be mapped read-only by specifying the
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.Dv SHM_RDONLY
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flag in
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.Fa shmflg .
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.Pp
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.Fn shmdt
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unmaps the shared memory segment that is currently mapped at
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.Fa shmaddr
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from the calling process' address space.
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.Fa shmaddr
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must be a value returned by a prior
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.Fn shmat
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call.
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A shared memory segment will remain in existence until it is
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removed by a call to
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.Xr shmctl 2
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with the
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.Dv IPC_RMID
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command.
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.Sh RETURN VALUES
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.Fn shmat
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returns the address at which the shared memory segment has been mapped into
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the calling process' address space when successful,
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.Fn shmdt
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returns 0 on successful completion.
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Otherwise, a value of \-1 is returned, and the global variable
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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 EACCES
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The calling process has no permission to access this shared memory segment.
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.It Bq Er ENOMEM
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There is not enough available data space for the calling process to
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map the shared memory segment.
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.It Bq Er EINVAL
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.Fa shmid
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is not a valid shared memory identifier.
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.Pp
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.Fa shmaddr
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specifies an illegal address.
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.It Bq Er EMFILE
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The number of shared memory segments has reached the system-wide limit.
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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 shmaddr
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is not the start address of a mapped shared memory segment.
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.El
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.Sh SEE ALSO
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.Xr ipcrm 1 ,
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.Xr ipcs 1 ,
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.Xr mmap 2 ,
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.Xr shmctl 2 ,
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.Xr shmget 2
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.Sh STANDARDS
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The
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.Nm shmat
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and
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.Nm shmdt
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system calls conform to
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.St -xsh5 .
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.Sh HISTORY
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Shared memory segments appeared in the first release of
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.At V .
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