'\" 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.
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.TH KSTAT_READ 3KSTAT "Aug 3, 2004"
.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
.na
\fB\fBEACCES\fR\fR
.ad
.RS 13n
An attempt was made to write to a non-writable kstat.
.RE

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

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

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

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

.sp
.ne 2
.na
\fB\fBEPERM\fR\fR
.ad
.RS 13n
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
.na
\fB\fB/dev/kstat\fR\fR
.ad
.RS 14n
kernel statistics driver
.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
_
Interface Stability	Stable
_
MT-Level	Unsafe
.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)