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Diffstat (limited to 'lib/libc/sys/shmctl.2')
| -rw-r--r-- | lib/libc/sys/shmctl.2 | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/lib/libc/sys/shmctl.2 b/lib/libc/sys/shmctl.2 new file mode 100644 index 0000000..98ddf13 --- /dev/null +++ b/lib/libc/sys/shmctl.2 @@ -0,0 +1,138 @@ +.\" +.\" 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 +.Sh NAME +.Nm shmctl +.Nd shared memory control +.Sh LIBRARY +.Lb libc +.Sh SYNOPSIS +.In sys/types.h +.In sys/ipc.h +.In 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 +.Vt shmid_ds +structure is defined as follows: +.\" +.\" I fiddled with the spaces a bit to make it fit well when viewed +.\" with nroff, but otherwise it is straight from sys/shm.h +.\" +.Bd -literal +struct shmid_ds { + struct ipc_perm shm_perm; /* operation permission structure */ + size_t 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 */ + int 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() */ +}; +.Ed +.Sh RETURN VALUES +.Rv -std shmctl +.Sh ERRORS +The +.Fn shmctl +system call +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. +.El +.Sh "SEE ALSO" +.Xr shmat 2 , +.Xr shmdt 2 , +.Xr shmget 2 , +.Xr ftok 3 |
