From a9157ce950dfe2fc30795d43b9d79b9d1bffc48b Mon Sep 17 00:00:00 2001 From: Jacob McDonnell Date: Sat, 25 Apr 2026 19:54:44 -0400 Subject: docs: Added All OpenBSD Manuals --- static/openbsd/man2/semctl.2 | 242 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 242 insertions(+) create mode 100644 static/openbsd/man2/semctl.2 (limited to 'static/openbsd/man2/semctl.2') diff --git a/static/openbsd/man2/semctl.2 b/static/openbsd/man2/semctl.2 new file mode 100644 index 00000000..63121717 --- /dev/null +++ b/static/openbsd/man2/semctl.2 @@ -0,0 +1,242 @@ +.\" $OpenBSD: semctl.2,v 1.18 2021/11/21 23:44:55 jan Exp $ +.\" $NetBSD: semctl.2,v 1.2 1997/03/27 08:20:40 mikel 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 $Mdocdate: November 21 2021 $ +.Dt SEMCTL 2 +.Os +.Sh NAME +.Nm semctl +.Nd semaphore control operations +.Sh SYNOPSIS +.In sys/sem.h +.Ft int +.Fn semctl "int semid" "int semnum" "int cmd" "union semun arg" +.Sh DESCRIPTION +The +.Fn semctl +system call provides a number of control operations on the semaphore specified +by +.Fa semnum +and +.Fa semid . +The operation to be performed is specified in +.Fa cmd +(see below). +.Fa arg +is a union of the following fields: +.Bd -literal + int val; /* value for SETVAL */ + struct semid_ds *buf; /* buffer for IPC_{STAT,SET} */ + u_short *array; /* array for GETALL & SETALL */ +.Ed +.Pp +The +.Bf -literal +semid_ds +.Ef +structure used in the +.Dv IPC_SET +and +.Dv IPC_STAT +commands is defined as follows in +.In sys/sem.h : +.Bd -literal +struct semid_ds { + struct ipc_perm sem_perm; /* operation permissions */ + struct sem *sem_base; /* semaphore set */ + u_short sem_nsems; /* number of sems in set */ + time_t sem_otime; /* last operation time */ + time_t sem_ctime; /* last change time */ +}; +.Ed +.Pp +The +.Bf -literal +ipc_perm +.Ef +structure used inside the +.Bf -literal +semid_ds +.Ef +structure is defined in +.In sys/ipc.h +and looks like this: +.Bd -literal +struct ipc_perm { + 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; /* r/w permission (see chmod(2)) */ + u_short seq; /* sequence # */ + /* (to generate unique msg/sem/shm id) */ + key_t key; /* user specified msg/sem/shm key */ +}; +.Ed +.Pp +.Fn semctl +provides the following operations: +.Bl -tag -width IPC_RMIDX +.It Dv GETVAL +Return the value of the semaphore. +.It Dv SETVAL +Set the value of the semaphore to +.Va arg.val . +.It Dv GETPID +Return the pid of the last process that did an operation on this semaphore. +.It Dv GETNCNT +Return the number of processes waiting to acquire the semaphore. +.It Dv GETZCNT +Return the number of processes waiting for the value of the semaphore to +reach 0. +.It Dv GETALL +Return the values for all the semaphores associated with +.Fa semid . +.It Dv SETALL +Set the values for all the semaphores that are associated with the semaphore +identifier +.Fa semid +to the corresponding values in +.Va arg.array . +.It Dv IPC_STAT +Gather statistics about a semaphore and place the information in the +.Bf -literal +semid_ds +.Ef +structure pointed to by +.Fa arg.buf +(see above). +.It Dv IPC_SET +Set the value of the +.Va sem_perm.uid , +.Va sem_perm.gid +and +.Va sem_perm.mode +fields in the structure associated with the semaphore. +The values are taken from the corresponding fields in the structure +pointed to by +.Fa arg.buf . +This operation can only be executed by the superuser, or a process that +has an effective user ID equal to either +.Va sem_perm.cuid +or +.Va sem_perm.uid +in the data structure associated with the message queue. +.It Dv IPC_RMID +Remove the semaphores associated with +.Fa semid +from the system and destroy the data structures associated with it. +Only the superuser or a process with an effective UID equal to the +.Va sem_perm.cuid +or +.Va sem_perm.uid +values in the data structure associated with the semaphore can do this. +.El +.Pp +The permission to read or change a message queue (see +.Xr semop 2 ) +is determined by the +.Va sem_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 sem_perm.cuid +field or the +.Va sem_perm.uid +field, and the +effective GID can match either +.Va sem_perm.cgid +or +.Va sem_perm.gid . +.Sh RETURN VALUES +For the +.Dv GETVAL , +.Dv GETPID , +.Dv GETNCNT , +and +.Dv GETZCNT +operations, +.Fn semctl +returns one of the values described above if successful. +All other operations will make +.Fn semctl +return 0 if no errors occur. +Otherwise \-1 is returned and +.Va errno +set to reflect the error. +.Sh ERRORS +.Fn semctl +will fail if: +.Bl -tag -width Er +.It Bq Er EPERM +.Fa cmd +is equal to +.Dv IPC_SET +or +.Dv IPC_RMID +and the caller is not the superuser, nor does +the effective UID match either the +.Va sem_perm.uid +or +.Va sem_perm.cuid +fields of the data structure associated with the message queue. +.It Bq Er EACCES +The caller has no operation permission for this semaphore. +.It Bq Er EINVAL +.Fa semid +is not a valid message semaphore identifier. +.Pp +.Va cmd +is not a valid command. +.It Bq Er EFAULT +.Fa arg.buf +or +.Fa arg.array +specify an invalid address. +.It Bq Er ERANGE +.Fa cmd +is equal to +.Dv SETVAL +or +.Dv SETALL +and +.Va arg.val +or the values in +.Va arg.array +are greater than the system-imposed limit. +.El +.Sh SEE ALSO +.Xr ipcrm 1 , +.Xr ipcs 1 , +.Xr semget 2 , +.Xr semop 2 -- cgit v1.2.3