minix/lib/libc/sys/msgget.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

151 lines
4 KiB
Groff

.\" $NetBSD: msgget.2,v 1.14 2004/05/13 10:20:58 wiz 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 May 13, 2004
.Dt MSGGET 2
.Os
.Sh NAME
.Nm msgget
.Nd get message queue identifier
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In sys/msg.h
.Ft int
.Fn msgget "key_t key" "int msgflg"
.Sh DESCRIPTION
The
.Fn msgget
system call returns the message queue identifier associated with
.Fa key .
A message queue identifier is a unique integer greater than zero.
.Pp
A message queue is created if either
.Fa key
is equal to
.Dv IPC_PRIVATE ,
or
.Fa key
does not have a message queue identifier associated with it and the
.Dv IPC_CREAT
bit is set in
.Fa msgflg .
If both the
.Dv IPC_CREAT
bit and the
.Dv IPC_EXCL
bit are set in
.Fa msgflg ,
and
.Fa key
has a message queue identifier associated with it already,
the operation will fail.
.Pp
If a new message queue is created, the data structure associated with it (the
.Va msqid_ds
structure, see
.Xr msgctl 2 )
is initialized as follows:
.Bl -bullet
.It
.Va msg_perm.cuid
and
.Va msg_perm.uid
are set to the effective uid of the calling process.
.It
.Va msg_perm.gid
and
.Va msg_perm.cgid
are set to the effective gid of the calling process.
.It
.Va msg_perm.mode
is set to the lower 9 bits of
.Fa msgflg .
.It
.Va msg_qnum ,
.Va msg_lspid ,
.Va msg_lrpid ,
.Va msg_rtime ,
and
.Va msg_stime
are set to 0.
.It
.Va msg_qbytes
is set to the system wide maximum value for the number of bytes in a queue
.Pq Dv MSGMNB .
.It
.Va msg_ctime
is set to the current time.
.El
.Sh RETURN VALUES
Upon successful completion a positive message queue identifier is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EACCES
A message queue is already associated with
.Fa key
and the caller has no permission to access it.
.It Bq Er EEXIST
Both
.Dv IPC_CREAT
and
.Dv IPC_EXCL
are set in
.Fa msgflg ,
and a message queue is already associated with
.Fa key .
.It Bq Er ENOSPC
A new message queue could not be created because the system limit for
the number of message queues has been reached.
.It Bq Er ENOENT
.Dv IPC_CREAT
is not set in
.Fa msgflg
and no message queue associated with
.Fa key
was found.
.El
.Sh SEE ALSO
.Xr msgctl 2 ,
.Xr msgrcv 2 ,
.Xr msgsnd 2 ,
.Xr ftok 3
.Sh STANDARDS
The
.Nm
system call conforms to
.St -xsh5 .
.Sh HISTORY
Message queues appeared in the first release of
.At V .