2fe8fb192f
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
181 lines
4.8 KiB
Groff
181 lines
4.8 KiB
Groff
.\" $NetBSD: msgsnd.2,v 1.18 2010/04/30 04:06:20 jruoho 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 April 30, 2010
|
|
.Dt MSGSND 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm msgsnd
|
|
.Nd send a message to a message queue
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In sys/msg.h
|
|
.Ft int
|
|
.Fn msgsnd "int msqid" "const void *msgp" "size_t msgsz" "int msgflg"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn msgsnd
|
|
function sends a message from the message queue specified in
|
|
.Fa msqid .
|
|
The
|
|
.Fa msgp
|
|
argument is a pointer to a user-defined structure containing the message.
|
|
This structure must contain a first field of type
|
|
.Vt long
|
|
that will indicate the user-defined type of the message.
|
|
The remaining fields will contain the contents of the message.
|
|
The following is an example of what this user-defined
|
|
structure might look like:
|
|
.Bd -literal -offset indent
|
|
struct mymsg {
|
|
long mtype; /* message type */
|
|
char mtext[1]; /* body of message */
|
|
};
|
|
.Ed
|
|
.Pp
|
|
The
|
|
.Va mtype
|
|
field is an integer greater than 0 that can
|
|
be used for selecting messages (see
|
|
.Xr msgrcv 2 ) .
|
|
The
|
|
.Va mtext
|
|
field is an array of bytes, with size up to the system limit
|
|
.Dv MSGMAX .
|
|
.Pp
|
|
If the number of bytes already on the message queue plus
|
|
.Fa msgsz
|
|
is greater than the maximum number of bytes in the message queue
|
|
.Pf ( Va msg_qbytes ,
|
|
see
|
|
.Xr msgctl 2 ) ,
|
|
or if the number of messages on all queues system-wide is already equal to
|
|
the system limit,
|
|
.Fa msgflg
|
|
determines the action of
|
|
.Fn msgsnd .
|
|
If
|
|
.Fa msgflg
|
|
has
|
|
.Dv IPC_NOWAIT
|
|
mask set in it, the call will return immediately.
|
|
If
|
|
.Fa msgflg
|
|
does not have
|
|
.Dv IPC_NOWAIT
|
|
set in it, the call will block until:
|
|
.Bl -bullet -offset indent
|
|
.It
|
|
The condition which caused the call to block no longer exists.
|
|
The message was sent.
|
|
.It
|
|
The message queue is removed, in which case \-1 will be returned and
|
|
.Va errno
|
|
set to
|
|
.Er EINVAL .
|
|
.It
|
|
The caller catches a signal.
|
|
The call returns with
|
|
.Va errno
|
|
set to
|
|
.Er EINTR .
|
|
.El
|
|
.Pp
|
|
After a successful call, the data structure associated with the message
|
|
queue is updated in the following way:
|
|
.Bl -bullet -offset indent
|
|
.It
|
|
.Va msg_qnum
|
|
is incremented by 1.
|
|
.It
|
|
.Va msg_lspid
|
|
is set to the pid of the calling process.
|
|
.It
|
|
.Va msg_stime
|
|
is set to the current time.
|
|
.El
|
|
.Sh RETURN VALUES
|
|
Upon successful completion, 0 is returned.
|
|
Otherwise, \-1 is returned and
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
.Fn msgsnd
|
|
will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EACCES
|
|
The calling process does not have write access to the message queue.
|
|
.It Bq Er EAGAIN
|
|
There was no space for this message either on the queue or in the whole
|
|
system, and
|
|
.Dv IPC_NOWAIT
|
|
was set in
|
|
.Fa msgflg .
|
|
.It Bq Er EFAULT
|
|
.Fa msgp
|
|
points to an invalid address.
|
|
.It Bq Er EINTR
|
|
The system call was interrupted by the delivery of a signal.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa msqid
|
|
argument is not a valid message queue identifier,
|
|
or the value of
|
|
.Fa mtype
|
|
is less than 1.
|
|
.Pp
|
|
The message queue was removed while
|
|
.Fn msgsnd
|
|
was waiting for a resource to become available in order to deliver the
|
|
message.
|
|
.Pp
|
|
The
|
|
.Fa msgsz
|
|
argument is greater than
|
|
.Va msg_qbytes
|
|
or
|
|
.Dv SSIZE_MAX .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr msgctl 2 ,
|
|
.Xr msgget 2 ,
|
|
.Xr msgrcv 2
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
system call conforms to
|
|
.St -xsh5
|
|
and
|
|
.St -p1003.1-2001 .
|
|
.Sh HISTORY
|
|
Message queues appeared in the first release of
|
|
.At V .
|