ntp_gettime, ntp_gettimex — get time parameters (NTP daemon interface)
#include <sys/timex.h>
int
ntp_gettime( |
struct ntptimeval *ntv); |
int
ntp_gettimex( |
struct ntptimeval *ntv); |
Both of these APIs return information to the caller via
the ntv argument, a
structure of the following type:
struct ntptimeval { struct timeval time;long maxerror;long esterror;long tai;};
The fields of this structure are as follows:
timeThe current time, expressed as a timeval structure:
struct timeval { time_t tv_sec;suseconds_t tv_usec;};
maxerrorMaximum error, in microseconds. This value can be
initialized by ntp_adjtime(3), and
is increased periodically (on Linux: each second), but
is clamped to an upper limit (the kernel constant
NTP_PHASE_MAX, with a
value of 16,000).
esterrorEstimated error, in microseconds. This value can be set via ntp_adjtime(3) to contain an estimate of the difference between the system clock and the true time. This value is not used inside the kernel.
taiTAI (Atomic International Time) offset.
ntp_gettime() returns an
ntptimeval structure in which
the time, maxerror, and esterror fields are filled
in.
ntp_gettimex() performs the
same task as ntp_gettime(), but
also returns information in the tai field.
The return values for ntp_gettime() and ntp_gettimex() are as for adjtimex(2). Given a
correct pointer argument, these functions always succeed.
The ntp_gettime() function
is available since glibc 2.1. The ntp_gettimex() function is available since
glibc 2.12.
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
ntp_gettime(), ntp_gettimex() |
Thread safety | MT-Safe |
ntp_gettime() is described
in the NTP Kernel Application Program Interface. ntp_gettimex() is a GNU extension.
This page is part of release 5.11 of the Linux man-pages project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
|
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