NAME

kstat_read, kstat_write — read or write kstat data

LIBRARY

Kernel Statistics Library (libkstat, -lkstat)

SYNOPSIS

#include <kstat.h>

kid_t
kstat_read(kstat_ctl_t *kc, kstat_t *ksp, void *buf);

kid_t
kstat_write(kstat_ctl_t *kc, kstat_t *ksp, void *buf);

DESCRIPTION

The kstat_read() function gets data from the kernel for the kstat pointed to by ksp. The ‘ksp->ks_data’ field is automatically allocated (or reallocated) to be large enough to hold all of the data. The ‘ksp->ks_ndata’ field is set to the number of data fields, ‘ksp->ks_data_size’ is set to the total size of the data, and ‘ksp->ks_snaptime’ is set to the high-resolution time at which the data snapshot was taken. If buf is non-null, the data is copied from ‘ksp->ks_data’ to buf.

The kstat_write() function writes data from buf, or from ‘ksp->ks_data’ if buf is NULL to the corresponding kstat in the kernel. Only a privileged user can use kstat_write().

RETURN VALUES

Upon successful completion, kstat_read() and kstat_write() return the current kstat chain ID (KCID). Otherwise, they return -1 and set errno to indicate the error.

FILES

/dev/kstat: kernel statistics driver character device

ERRORS

The kstat_read() and kstat_write() functions will fail if:

EACCES: An attempt was made to write to a non-writable kstat.
EAGAIN: The kstat was temporarily unavailable for reading or writing.
EINVAL: An attempt was made to write data to a kstat, but the number of elements or the data size does not match.
ENOMEM: Insufficient storage space is available.
ENXIO: The given kstat could not be located for reading or writing.
EOVERFLOW
EPERM: An attempt was made to write to a kstat, but {PRIV_SYS_CONFIG} was not asserted in the effective privilege set.

INTERFACE STABILITY

Committed

MT-LEVEL

Unsafe