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authorTheo de Raadt <deraadt@cvs.openbsd.org>1995-12-14 02:22:02 +0000
committerTheo de Raadt <deraadt@cvs.openbsd.org>1995-12-14 02:22:02 +0000
commitb4f690c1be69b42a55df1174f6e4bf67bbfee298 (patch)
tree62f7249c04f4d6b3821d0fbadfc4843a86fa5e5a /lib/libc/sys/shmctl.2
parent5d801f0e5d756fb4b71ee4d37fd8330778dbae6e (diff)
properly add them...
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+.\" $NetBSD: shmctl.2,v 1.1 1995/10/16 23:49:30 jtc 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 August 17, 1995
+.Dt SHMCTL 2
+.Os NetBSD
+.Sh NAME
+.Nm shmctl
+.Nd shared memory control operations
+.Sh SYNOPSIS
+.Fd #include <sys/types.h>
+.Fd #include <sys/ipc.h>
+.Fd #include <sys/msg.h>
+.Ft int
+.Fn shmctl "int shmid" "int cmd" "struct shmid_ds *buf"
+.Sh DESCRIPTION
+The
+.Fn shmctl
+system call performs some control operations on the shared memory area
+specified by
+.Fa shmid .
+
+Each shared memory segment has a data structure associated with it,
+parts of which may be altered by
+.Fn shmctl
+and parts of which determine the actions of
+.Fn shmctl .
+
+This structure is defined as follows in
+.Aq Pa sys/shm.h :
+.Bd -literal
+struct shmid_ds {
+ struct ipc_perm shm_perm; /* operation permissions */
+ int shm_segsz; /* size of segment in bytes */
+ pid_t shm_lpid; /* pid of last shm op */
+ pid_t shm_cpid; /* pid of creator */
+ short 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() */
+ void *shm_internal; /* sysv stupidity */
+};
+.Ed
+The
+.Bf -literal
+ipc_perm
+.Ef
+structure used inside the
+.Bf -literal
+shmid_ds
+.Ef
+structure is defined in
+.Aq Pa sys/ipc.h
+and looks like this:
+.Bd -literal
+struct ipc_perm {
+ ushort cuid; /* creator user id */
+ ushort cgid; /* creator group id */
+ ushort uid; /* user id */
+ ushort gid; /* group id */
+ ushort mode; /* r/w permission (see chmod(2)) */
+ ushort seq; /* sequence # (to generate unique msg/sem/shm id) */
+ key_t key; /* user specified msg/sem/shm key */
+};
+.Ed
+
+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 queue can do this.
+.El
+
+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 EPERM
+.Fa cmd
+is equal to IPC_SET or 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.
+
+An attempt is made to increase the value of
+.Va shm_qbytes
+through IPC_SET
+but the caller is not the super-user.
+.It Bq Er EACCESS
+The command is IPC_STAT
+and the caller has no read permission for this shared memory segment.
+.It Bq Er EINVAL
+.Fa shmid
+is not a valid shared memory segment identifier.
+
+.Va cmd
+is not a valid command.
+.It Bq Er EFAULT
+.Fa buf
+specifies an invalid address.
+.El
+.Sh SEE ALSO
+.Xr shmat 2 ,
+.Xr shmdt 2 ,
+.Xr shmget 2