diff options
author | Theo de Raadt <deraadt@cvs.openbsd.org> | 1995-12-14 02:22:02 +0000 |
---|---|---|
committer | Theo de Raadt <deraadt@cvs.openbsd.org> | 1995-12-14 02:22:02 +0000 |
commit | b4f690c1be69b42a55df1174f6e4bf67bbfee298 (patch) | |
tree | 62f7249c04f4d6b3821d0fbadfc4843a86fa5e5a /lib/libc/sys/shmctl.2 | |
parent | 5d801f0e5d756fb4b71ee4d37fd8330778dbae6e (diff) |
properly add them...
Diffstat (limited to 'lib/libc/sys/shmctl.2')
-rw-r--r-- | lib/libc/sys/shmctl.2 | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/lib/libc/sys/shmctl.2 b/lib/libc/sys/shmctl.2 new file mode 100644 index 00000000000..fbb33ab0e31 --- /dev/null +++ b/lib/libc/sys/shmctl.2 @@ -0,0 +1,187 @@ +.\" $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 |