'\" te
.\" Copyright (c) 2003, Sun Microsystems, Inc. All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH PORT_ALERT 3C "Oct 1, 2003"
.SH NAME
port_alert \- set a port in alert mode
.SH SYNOPSIS
.LP
.nf
#include <port.h>

\fBint\fR \fBport_alert\fR(\fBint\fR \fIport\fR, \fBint\fR \fIflags\fR, \fBint\fR \fIevents\fR, \fBvoid *\fR\fIuser\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBport_alert()\fR function transitions a port into or out of alert mode.
A port in alert mode immediately awakens all threads blocked in
\fBport_get\fR(3C) or \fBport_getn\fR(3C). These threads return with an alert
notification that consists of a single \fBport_event_t\fR structure with the
source \fBPORT_SOURCE_ALERT\fR. Subsequent threads trying to retrieve events
from a port that is in alert mode will return immediately with the alert
notification.
.sp
.LP
A port is transitioned into alert mode by calling the \fBport_alert()\fR
function with a non-zero \fIevents\fR parameter.  The specified \fIevents\fR
and \fIuser\fR parameters will be made available in the \fBportev_events\fR and
the \fBportev_user\fR members of the alert notification, respectively. The
\fIflags\fR argument determines the mode of operation of the alert mode:
.RS +4
.TP
.ie t \(bu
.el o
If \fIflags\fR is set to \fBPORT_ALERT_SET\fR, \fBport_alert()\fR sets the port
in alert mode independent of the current state of the port.  The
\fBportev_events\fR and \fBportev_user\fR members are set or updated
accordingly.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If \fIflags\fR is set to \fBPORT_ALERT_UPDATE\fR and the port is not in alert
mode, \fBport_alert()\fR transitions the port into alert mode.  The
\fBportev_events\fR and \fBportev_user\fR members are set accordingly.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If \fIflags\fR is set to \fBPORT_ALERT_UPDATE\fR and the port is already in
alert mode, \fBport_alert()\fR returns with an error value of \fBEBUSY\fR.
.RE
.sp
.LP
\fBPORT_ALERT_SET\fR and \fBPORT_ALERT_UPDATE\fR are mutually exclusive.
.sp
.LP
A port is transitioned out of alert mode by calling the \fBport_alert()\fR
function with a zero \fIevents\fR parameter.
.sp
.LP
Events can be queued to a port that is in alert mode, but they will not be
retrievable until the port is transitioned out of alert mode.
.SH RETURN VALUES
.sp
.LP
Upon succesful completion, 0 is returned. Otherwise, -1 is returned and
\fBerrno\fR is set to indicate the error.
.SH ERRORS
.sp
.LP
The \fBport_alert()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEBADF\fR\fR
.ad
.RS 10n
The port identifier is not valid.
.RE

.sp
.ne 2
.na
\fB\fBEBADFD\fR\fR
.ad
.RS 10n
The \fIport\fR argument is not an event port file descriptor.
.RE

.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 10n
The port is already in alert mode.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
Mutually exclusive \fIflags\fR are set.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Architecture	all
_
Interface Stability	Evolving
_
MT-Level	Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBport_associate\fR(3C), \fBport_create\fR(3C), \fBport_get\fR(3C),
\fBport_send\fR(3C), \fBattributes\fR(5)