mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-29 12:03:03 +00:00
140 lines
4.5 KiB
Groff
140 lines
4.5 KiB
Groff
.\"
|
|
.\" Copyright (c) 1995 David Hovemeyer <daveho@infocom.com>
|
|
.\"
|
|
.\" 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.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 DEVELOPERS 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd July 17, 1995
|
|
.Dt SHMCTL 2
|
|
.Os FreeBSD
|
|
.Sh NAME
|
|
.Nm shmctl
|
|
.Nd shared memory control
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.Fd #include <machine/param.h>
|
|
.Fd #include <sys/types.h>
|
|
.Fd #include <sys/ipc.h>
|
|
.Fd #include <sys/shm.h>
|
|
.Ft int
|
|
.Fn shmctl "int shmid" "int cmd" "struct shmid_ds *buf"
|
|
.Sh DESCRIPTION
|
|
Performs the action specified by
|
|
.Fa cmd
|
|
on the shared memory segment identified by
|
|
.Fa shmid :
|
|
.Bl -tag -width SHM_UNLOCKX
|
|
.It Dv IPC_STAT
|
|
Fetch the segment's
|
|
.Fa "struct shmid_ds" ,
|
|
storing it in the memory pointed to by
|
|
.Fa buf .
|
|
.\"
|
|
.\" XXX need to make sure that this is correct for FreeBSD
|
|
.\"
|
|
.It Dv IPC_SET
|
|
Changes the
|
|
.Fa shm_perm.uid ,
|
|
.Fa shm_perm.gid ,
|
|
and
|
|
.Fa shm_perm.mode
|
|
members of the segment's
|
|
.Fa "struct shmid_ds"
|
|
to match those of the struct pointed to by
|
|
.Fa buf .
|
|
The calling process's effective uid must
|
|
match either
|
|
.Fa shm_perm.uid
|
|
or
|
|
.Fa shm_perm.cuid ,
|
|
or it must have superuser privileges.
|
|
.It Dv IPC_RMID
|
|
Removes the segment from the system. The removal will not take
|
|
effect until all processes having attached the segment have exited;
|
|
however, once the IPC_RMID operation has taken place, no further
|
|
processes will be allowed to attach the segment. For the operation
|
|
to succeed, the calling process's effective uid must match
|
|
.Fa shm_perm.uid
|
|
or
|
|
.Fa shm_perm.cuid ,
|
|
or the process must have superuser privileges.
|
|
.\" .It Dv SHM_LOCK
|
|
.\" Locks the segment in memory. The calling process must have
|
|
.\" superuser privileges. Not implemented in FreeBSD.
|
|
.\" .It Dv SHM_UNLOCK
|
|
.\" Unlocks the segment from memory. The calling process must
|
|
.\" have superuser privileges. Not implemented in FreeBSD.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Fa shmid_ds
|
|
struct is defined as follows:
|
|
.\"
|
|
.\" I fiddled with the spaces a bit to make it fit well when viewed
|
|
.\" with nroff, but otherwise it's straight from sys/shm.h
|
|
.\"
|
|
.Bd -literal
|
|
struct shmid_ds {
|
|
struct ipc_perm shm_perm; /* operation permission structure */
|
|
int shm_segsz; /* size of segment in bytes */
|
|
pid_t shm_lpid; /* process ID of last shared memory op */
|
|
pid_t shm_cpid; /* process ID of creator */
|
|
short shm_nattch; /* number of current attaches */
|
|
time_t shm_atime; /* time of last shmat() */
|
|
time_t shm_dtime; /* time of last shmdt() */
|
|
time_t shm_ctime; /* time of last change by shmctl() */
|
|
void *shm_internal; /* sysv stupidity */
|
|
};
|
|
.Ed
|
|
.Sh RETURN VALUES
|
|
Upon successful completion,
|
|
.Fn shmctl
|
|
returns 0. Otherwise, it returns -1 and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
.Fn Shmctl
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
Invalid operation, or
|
|
no shared memory segment was found corresponding to
|
|
.Fa shmid .
|
|
.\"
|
|
.\" XXX I think the following is right: ipcperm() only returns EPERM
|
|
.\" when an attempt is made to modify (IPC_M) by a non-creator
|
|
.\" non-owner
|
|
.It Bq Er EPERM
|
|
The calling process's effective uid does not match the uid of
|
|
the shared memory segment's owner or creator.
|
|
.It Bq Er EACCES
|
|
Permission denied due to mismatch between operation and mode of
|
|
shared memory segment.
|
|
.Sh "SEE ALSO"
|
|
.Xr shmat 2 ,
|
|
.Xr shmdt 2 ,
|
|
.Xr shmget 2 ,
|
|
.Xr ftok 3
|