This patch imports the unmodified current version of NetBSD libc. The NetBSD includes are in /nbsd_include, while the libc code itself is split between lib/nbsd_libc and common/lib/libc.
209 lines
5.8 KiB
Groff
209 lines
5.8 KiB
Groff
.\" $NetBSD: shmctl.2,v 1.21 2010/03/22 19:30:55 joerg Exp $
|
|
.\"
|
|
.\" Copyright (c) 1995 Frank van der Linden
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. All advertising materials mentioning features or use of this software
|
|
.\" must display the following acknowledgement:
|
|
.\" This product includes software developed for the NetBSD Project
|
|
.\" by Frank van der Linden
|
|
.\" 4. The name of the author may not be used to endorse or promote products
|
|
.\" derived from this software without specific prior written permission
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
.\"
|
|
.Dd November 25, 2006
|
|
.Dt SHMCTL 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm shmctl
|
|
.Nd shared memory control operations
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/shm.h
|
|
.Ft int
|
|
.Fn shmctl "int shmid" "int cmd" "struct shmid_ds *buf"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn shmctl
|
|
system call performs control operations on the shared memory segment
|
|
specified by
|
|
.Fa shmid .
|
|
.Pp
|
|
Each shared memory segment has a
|
|
.Sy shmid_ds
|
|
structure associated with it which contains the following members:
|
|
.Bd -literal
|
|
struct ipc_perm shm_perm; /* operation permissions */
|
|
size_t shm_segsz; /* size of segment in bytes */
|
|
pid_t shm_lpid; /* pid of last shm op */
|
|
pid_t shm_cpid; /* pid of creator */
|
|
shmatt_t shm_nattch; /* # of current attaches */
|
|
time_t shm_atime; /* last shmat() time */
|
|
time_t shm_dtime; /* last shmdt() time */
|
|
time_t shm_ctime; /* last change by shmctl() */
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Sy ipc_perm
|
|
structure used inside the
|
|
.Sy shmid_ds
|
|
structure is defined in
|
|
.In sys/ipc.h
|
|
and contains the following members:
|
|
.Bd -literal
|
|
uid_t cuid; /* creator user id */
|
|
gid_t cgid; /* creator group id */
|
|
uid_t uid; /* user id */
|
|
gid_t gid; /* group id */
|
|
mode_t mode; /* permission (lower 9 bits) */
|
|
.Ed
|
|
.Pp
|
|
The operation to be performed by
|
|
.Fn shmctl
|
|
is specified in
|
|
.Fa cmd
|
|
and is one of:
|
|
.Bl -tag -width IPC_RMIDX
|
|
.It Dv IPC_STAT
|
|
Gather information about the shared memory segment and place it in the
|
|
structure pointed to by
|
|
.Fa buf .
|
|
.It Dv IPC_SET
|
|
Set the value of the
|
|
.Va shm_perm.uid ,
|
|
.Va shm_perm.gid
|
|
and
|
|
.Va shm_perm.mode
|
|
fields in the structure associated with
|
|
.Fa shmid .
|
|
The values are taken from the corresponding fields in the structure
|
|
pointed to by
|
|
.Fa buf .
|
|
This operation can only be executed by the super-user, or a process that
|
|
has an effective user id equal to either
|
|
.Va shm_perm.cuid
|
|
or
|
|
.Va shm_perm.uid
|
|
in the data structure associated with the shared memory segment.
|
|
.It Dv IPC_RMID
|
|
Remove the shared memory segment specified by
|
|
.Fa shmid
|
|
and destroy the data associated with it.
|
|
Only the super-user or a process with an effective uid equal to the
|
|
.Va shm_perm.cuid
|
|
or
|
|
.Va shm_perm.uid
|
|
values in the data structure associated with the segment can do this.
|
|
.It Dv SHM_LOCK
|
|
Lock the shared memory segment specified by
|
|
.Fa shmid
|
|
in memory.
|
|
This operation can only be executed by the super-user.
|
|
.It Dv SHM_UNLOCK
|
|
Unlock the shared memory segment specified by
|
|
.Fa shmid .
|
|
This operation can only be executed by the super-user.
|
|
.El
|
|
.Pp
|
|
The read and write permissions on a shared memory identifier
|
|
are determined by the
|
|
.Va shm_perm.mode
|
|
field in the same way as is
|
|
done with files (see
|
|
.Xr chmod 2 ) ,
|
|
but the effective uid can match either the
|
|
.Va shm_perm.cuid
|
|
field or the
|
|
.Va shm_perm.uid
|
|
field, and the
|
|
effective gid can match either
|
|
.Va shm_perm.cgid
|
|
or
|
|
.Va shm_perm.gid .
|
|
.Sh RETURN VALUES
|
|
Upon successful completion, a value of 0 is returned.
|
|
Otherwise, \-1 is returned and the global variable
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
.Fn shmctl
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EACCES
|
|
The command is
|
|
.Dv IPC_STAT
|
|
and the caller has no read permission for this shared memory segment.
|
|
.It Bq Er EFAULT
|
|
.Fa buf
|
|
specifies an invalid address.
|
|
.It Bq Er EINVAL
|
|
.Fa shmid
|
|
is not a valid shared memory segment identifier.
|
|
.Pp
|
|
.Va cmd
|
|
is not a valid command.
|
|
.It Bq Er ENOMEM
|
|
The
|
|
.Fa cmd
|
|
is equal to
|
|
.Dv SHM_LOCK
|
|
and there is not enough physical memory.
|
|
.It Bq Er EPERM
|
|
.Fa cmd
|
|
is equal to
|
|
.Dv IPC_SET
|
|
or
|
|
.Dv IPC_RMID
|
|
and the caller is not the super-user, nor does
|
|
the effective uid match either the
|
|
.Va shm_perm.uid
|
|
or
|
|
.Va shm_perm.cuid
|
|
fields of the data structure associated with the shared memory segment.
|
|
.Pp
|
|
An attempt was made to increase the value of
|
|
.Va shm_qbytes
|
|
through
|
|
.Dv IPC_SET
|
|
but the caller is not the super-user.
|
|
.Pp
|
|
The
|
|
.Fa cmd
|
|
is equal to
|
|
.Dv SHM_LOCK
|
|
or
|
|
.Dv SHM_UNLOCK
|
|
and the caller is not the super-user.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr ipcrm 1 ,
|
|
.Xr ipcs 1 ,
|
|
.Xr shmat 2 ,
|
|
.Xr shmget 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
system call conforms to
|
|
.St -xsh5 .
|
|
.Sh HISTORY
|
|
Shared memory segments appeared in the first release of
|
|
.At V .
|