path: root/usr/src/man/man3c/port_get.3c

'\" te
.\" Copyright (c) 2007, 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.
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.TH port_get 3C "31 Jan 2007" "SunOS 5.11" "Standard C Library Functions"
.SH NAME
port_get, port_getn \- retrieve event information from a port
.SH SYNOPSIS
.LP
.nf
#include <port.h>

\fBint\fR \fBport_get\fR(\fBint\fR \fIport\fR, \fBport_event_t *\fR\fIpe\fR,
     \fBconst timespec_t *\fR\fItimeout\fR);
.fi

.LP
.nf
\fBint\fR \fBport_getn\fR(\fBint\fR \fIport\fR, \fBport_event_t\fR \fIlist\fR[], \fBuint_t\fR \fImax\fR,
     \fBuint_t *\fR\fInget\fR, \fBconst timespec_t *\fR\fItimeout\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBport_get()\fR and \fBport_getn()\fR functions retrieve events from a
port. The \fBport_get()\fR function retrieves at most a single event. The
\fBport_getn()\fR function can retrieve multiple events.
.sp
.LP
The \fIpe\fR argument points to an uninitialized \fBport_event_t\fR structure
that is filled in by the system when the \fBport_get()\fR function returns
successfully.
.sp
.LP
The \fBport_event_t\fR structure contains the following members:
.sp
.in +2
.nf
int       portev_events;   /* detected events           */
ushort_t  portev_source;   /* event source              */
uintptr_t portev_object;   /* specific to event source  */
void      *portev_user;    /* user defined cookie       */
.fi
.in -2

.sp
.LP
The \fBportev_events\fR and \fBportev_object\fR members are specific to the
event source. The \fBportev_events\fR denotes the delivered events. The
\fBportev_object\fR refers to the associated object (see
\fBport_create\fR(3C)). The \fBportev_source\fR member specifies the source of
the event. The \fBportev_user\fR member is a user-specified value.
.sp
.LP
If the \fItimeout\fR pointer is \fINULL\fR, the \fBport_get()\fR function
blocks until an event is available. To poll for an event without waiting,
\fItimeout\fR should point to a zeroed \fBtimespec\fR. A non-zeroed
\fBtimespec\fR specifies the desired time to wait for events. The
\fBport_get()\fR function returns before the timeout elapses if an event is
available, a signal occurs, a port is closed by another thread, or the port is
in or enters alert mode. See \fBport_alert\fR(3C) for details on alert mode.
.sp
.LP
The \fBport_getn()\fR function can retrieve multiple events from a port. The
\fIlist\fR argument is an array of uninitialized \fBport_event_t\fR structures
that is filled in by the system when the \fBport_getn()\fR function returns
succesfully. The \fInget\fR argument points to the desired number of events to
be retrieved. The \fImax\fR parameter specifies the maximum number of events
that can be returned in \fIlist\fR[]. If \fImax\fR is 0, the value pointed to
by \fInget\fR is set to the number of events available on the port. The
\fBport_getn()\fR function returns immediately but no events are retrieved.
.sp
.LP
The \fBport_getn()\fR function block until the desired number of events are
available, the timeout elapses, a signal occurs, a port is closed by another
thread, or the port is in or enters alert mode.
.sp
.LP
On return, the value pointed to by \fInget\fR is updated to the actual number
of events retrieved in list.
.sp
.LP
Threads calling the \fBport_get()\fR function might starve threads waiting in
the \fBport_getn()\fR function for more than one event.  Similarly, threads
calling the \fBport_getn()\fR function for \fIn\fR events might starve threads
waiting in the \fBport_getn()\fR function for more than \fIn\fR events.
.sp
.LP
The \fBport_get()\fR and the \fBport_getn()\fR functions ignore non-shareable
events (see \fBport_create\fR(3C)) generated by other processes.
.SH RETURN VALUES
.sp
.LP
Upon succesful completion, 0 is returned. Otherwise, -1 is returned and errno
is set to indicate the error.
.SH ERRORS
.sp
.LP
The \fBport_get()\fR and \fBport_getn()\fR functions will fail if:
.sp
.ne 2
.mk
.na
\fB\fBEBADF\fR\fR
.ad
.RS 10n
.rt  
The \fIport\fR identifier is not valid.
.RE

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

.sp
.ne 2
.mk
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
.rt  
Event or event list can not be delivered (\fIlist\fR[] pointer and/or user
space reserved to accomodate the list of events is not reasonable), or the
\fItimeout\fR argument is not reasonable.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEINTR\fR\fR
.ad
.RS 10n
.rt  
A signal was caught during the execution of the function.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
.rt  
The \fItimeout\fR element \fBtv_sec\fR is < 0 or the \fItimeout\fR element
\fBtv_nsec\fR is < 0 or > 1000000000.
.RE

.sp
.ne 2
.mk
.na
\fB\fBETIME\fR\fR
.ad
.RS 10n
.rt  
The time interval expired before the expected number of events have been posted
to the port.
.RE

.sp
.LP
The \fBport_getn()\fR function will fail if:
.sp
.ne 2
.mk
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
.rt  
The \fIlist\fR[] argument is \fINULL\fR, the \fInget\fR argument is \fINULL\fR,
or the content of \fInget\fR is > \fImax\fR and \fImax\fR is > 0.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
.rt  
The \fItimeout\fR argument is not reasonable.
.RE

.sp
.ne 2
.mk
.na
\fB\fBETIME\fR\fR
.ad
.RS 10n
.rt  
The time interval expired before the expected number of events have been posted
to the port (original value in \fInget\fR), or \fInget\fR is updated with the
number of returned \fBport_event_t\fR structures in \fIlist\fR[].
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRSend a user event (PORT_SOURCE_USER) to a port and retrieve it
with \fBport_get()\fR.
.sp
.LP
The following example sends a user event (\fBPORT_SOURCE_USER\fR) to a port and
retrieves it with \fBport_get()\fR. The \fBportev_user\fR and
\fBportev_events\fR members of the \fBport_event_t\fR structure are the same as
the corresponding user and events arguments of the \fBport_send\fR(3C)
function.

.sp
.in +2
.nf
#include <port.h>

int             myport;
port_event_t    pe;
struct timespec timeout;
int             ret;
void            *user;
uintptr_t       object;

myport = port_create();
if (myport < 0) {
        /* port creation failed ... */
        ...
        return(...);
}
\&...
events = 0x01;          /* own event definition(s) */
object = <myobject>;
user = <my_own_value>;
ret = port_send(myport, events, user);
if (ret == -1) {
        /* error detected ... */
        ...
        close(myport);
        return (...);
}

/*
 * The following code could also be executed in another thread or
 * process.
 */
timeout.tv_sec = 1;     /* user defined */
timeout.tv_nsec = 0;
ret = port_get(myport, &pe, &timeout);
if (ret == -1) {
        /*
         * error detected :
         * - EINTR or ETIME : log error code and try again ...
         * - Other kind of errors : may have to close the port ...
         */
        return(...);
}

/*
 * After port_get() returns successfully, the port_event_t
 * structure will be filled with:
 * pe.portev_source =   PORT_SOURCE_USER
 * pe.portev_events = 0x01
 * pe.portev_object = <myobject>
 * pe.portev_user = <my_own_value>
 */
\&...
close(myport);
.fi
.in -2

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

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Architectureall
_
Interface StabilityEvolving
_
MT-LevelSafe
.TE

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