'\" te
.\" Copyright (c) 2004, 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 kstat_read 3KSTAT "3 Aug 2004" "SunOS 5.11" "Kernel Statistics Library Functions"
.SH NAME
kstat_read, kstat_write \- read or write kstat data
.SH SYNOPSIS
.LP
.nf
\fBcc\fR [ \fIflag\fR\&.\|.\|. ] \fIfile\fR\&.\|.\|. \fB-lkstat\fR [ \fIlibrary\fR\&.\|.\|. ]
#include <kstat.h>

\fBkid_t\fR \fBkstat_read\fR(\fBkstat_ctl_t *\fR\fIkc\fR, \fBkstat_t *\fR\fIksp\fR, \fBvoid *\fR\fIbuf\fR);
.fi

.LP
.nf
\fBkid_t\fR \fBkstat_write\fR(\fBkstat_ctl_t *\fR\fIkc\fR, \fBkstat_t *\fR\fIksp\fR, \fBvoid *\fR\fIbuf\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBkstat_read()\fR function gets data from the kernel for the kstat pointed
to by \fIksp\fR. The \fIksp\fR->\fBks_data\fR field is automatically allocated
(or reallocated) to be large enough to hold all of the data. The
\fIksp\fR->\fBks_ndata\fR field is set to the number of data fields,
\fIksp\fR->\fBks_data_size\fR is set to the total size of the data, and
\fIksp\fR->\fBks_snaptime\fR is set to the high-resolution time at which the
data snapshot was taken. If \fIbuf\fR is  non-null, the data is copied from
\fIksp\fR->\fBks_data\fR to \fIbuf\fR.
.sp
.LP
The \fBkstat_write()\fR function writes data from \fIbuf\fR, or from
\fIksp\fR->\fBks_data\fR if \fIbuf\fR is \fINULL\fR, to the corresponding kstat
in the kernel.  Only the superuser can use \fBkstat_write()\fR.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBkstat_read()\fR and \fBkstat_write()\fR return
the current kstat chain ID (KCID). Otherwise, they return \(mi1 and set
\fBerrno\fR to indicate the error.
.SH ERRORS
.sp
.LP
The \fBkstat_read()\fR and \fBkstat_write()\fR functions will fail if:
.sp
.ne 2
.mk
.na
\fB\fBEACCES\fR\fR
.ad
.RS 13n
.rt  
An attempt was made to write to a non-writable kstat.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 13n
.rt  
The kstat was temporarily unavailable for reading or writing.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 13n
.rt  
An attempt was made to write data to a kstat, but the number of elements or the
data size does not match.
.RE

.sp
.ne 2
.mk
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 13n
.rt  
Insufficient storage space is available.
.RE

.sp
.ne 2
.mk
.na
\fB\fBENXIO\fR\fR
.ad
.RS 13n
.rt  
The given kstat could not be located for reading or writing.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEOVERFLOW\fR\fR
.ad
.RS 13n
.rt  
The data for the given kstat was too large to be stored in the structure.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEPERM\fR\fR
.ad
.RS 13n
.rt  
An attempt was made to write to a kstat, but {\fBPRIV_SYS_CONFIG\fR} was not
asserted in the effective privilege set.
.RE

.SH FILES
.sp
.ne 2
.mk
.na
\fB\fB/dev/kstat\fR\fR
.ad
.RS 14n
.rt  
kernel statistics driver
.RE

.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
_
Interface StabilityStable
_
MT-LevelUnsafe
.TE

.SH SEE ALSO
.sp
.LP
\fBkstat\fR(3KSTAT), \fBkstat_chain_update\fR(3KSTAT),
\fBkstat_lookup\fR(3KSTAT), \fBkstat_open\fR(3KSTAT), \fBattributes\fR(5),
\fBprivileges\fR(5)