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
174 lines
4.5 KiB
Groff
174 lines
4.5 KiB
Groff
.\" $NetBSD: shmget.2,v 1.22 2008/10/27 16:49:10 wiz 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 October 27, 2008
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.Dt SHMGET 2
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.Os
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.Sh NAME
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.Nm shmget
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.Nd get shared memory segment
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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 int
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.Fn shmget "key_t key" "size_t size" "int shmflg"
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.Sh DESCRIPTION
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.Fn shmget
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returns the shared memory identifier associated with the key
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.Fa key .
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.Pp
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A shared memory segment is created if either
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.Fa key
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is equal to
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.Dv IPC_PRIVATE ,
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or
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.Fa key
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does not have a shared memory segment identifier associated with it, and the
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.Dv IPC_CREAT
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bit is set in
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.Fa shmflg .
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If both the
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.Dv IPC_CREAT
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bit and the
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.Dv IPC_EXCL
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bit are set in
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.Fa shmflg ,
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and
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.Fa key
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has a shared memory segment identifier associated with it already,
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the operation will fail.
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.Pp
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If a new shared memory segment is created, the data structure
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associated with it (the
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.Va shmid_ds
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structure, see
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.Xr shmctl 2 )
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is initialized as follows:
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.Bl -bullet
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.It
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.Va shm_perm.cuid
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and
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.Va shm_perm.uid
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are set to the effective uid of the calling process.
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.It
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.Va shm_perm.gid
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and
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.Va shm_perm.cgid
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are set to the effective gid of the calling process.
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.It
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.Va shm_perm.mode
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is set to the lower 9 bits of
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.Fa shmflg .
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.It
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.Va shm_lpid ,
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.Va shm_nattch ,
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.Va shm_atime ,
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and
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.Va shm_dtime
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are set to 0.
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.It
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.Va shm_ctime
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is set to the current time.
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.It
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.Va shm_segsz
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is set to the value of
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.Fa size .
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.El
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.Sh RETURN VALUES
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Upon successful completion a positive shared memory segment identifier
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is returned.
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Otherwise, \-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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.Bl -tag -width Er
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.It Bq Er EACCES
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A shared memory segment is already associated with
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.Fa key
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and the caller has no permission to access it.
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.It Bq Er EEXIST
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Both
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.Dv IPC_CREAT
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and
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.Dv IPC_EXCL
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are set in
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.Fa shmflg ,
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and a shared memory segment is already associated with
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.Fa key .
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.It Bq Er EINVAL
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No shared memory segment is to be created, and a shared memory segment
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exists for
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.Fa key ,
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but the size of the segment associated with it is less
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than
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.Fa size ,
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which is non-zero.
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.Pp
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A shared memory segment
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.Em is
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to be created, and
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.Fa size
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is less than the system imposed minimum, or greater than the system
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imposed maximum (refer to the
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.Li kern.ipc
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values in
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.Xr sysctl 7 ) .
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.It Bq Er ENOENT
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.Dv IPC_CREAT
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is not set in
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.Fa shmflg
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and no shared memory segment associated with
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.Fa key
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was found.
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.It Bq Er ENOMEM
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There is not enough memory left to create a shared memory segment of the
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requested size.
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.It Bq Er ENOSPC
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A new shared memory identifier could not be created because the system limit
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for the number of shared memory identifiers has been reached.
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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 shmat 2 ,
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.Xr shmctl 2 ,
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.Xr ftok 3 ,
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.Xr sysctl 7
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.Sh STANDARDS
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The
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.Nm
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system call conforms 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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