получить временные параметры (интерфейс демона NTP) (get time parameters (NTP daemon interface))
Имя (Name)
ntp_gettime, ntp_gettimex - get time parameters (NTP daemon
interface)
Синопсис (Synopsis)
#include <sys/timex.h>
int ntp_gettime(struct ntptimeval *ntv);
int ntp_gettimex(struct ntptimeval *ntv);
Описание (Description)
Both of these APIs return information to the caller via the ntv
argument, a structure of the following type:
struct ntptimeval {
struct timeval time; /* Current time */
long maxerror; /* Maximum error */
long esterror; /* Estimated error */
long tai; /* TAI offset */
/* Further padding bytes allowing for future expansion */
};
The fields of this structure are as follows:
time The current time, expressed as a timeval structure:
struct timeval {
time_t tv_sec; /* Seconds since the Epoch */
suseconds_t tv_usec; /* Microseconds */
};
maxerror
Maximum 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).
esterror
Estimated 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.
tai TAI (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.
Возвращаемое значение (Return value)
The return values for ntp_gettime() and ntp_gettimex() are as for
adjtimex(2). Given a correct pointer argument, these functions
always succeed.
Версии (Versions)
The ntp_gettime() function is available since glibc 2.1. The
ntp_gettimex() function is available since glibc 2.12.
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ntp_gettime(), ntp_gettimex() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
ntp_gettime() is described in the NTP Kernel Application Program
Interface. ntp_gettimex() is a GNU extension.
Смотри также (See also)
adjtimex(2), ntp_adjtime(3), time(7)
NTP "Kernel Application Program Interface"
⟨http://www.slac.stanford.edu/comp/unix/package/rtems/src/ssrlApps/ntpNanoclock/api.htm⟩
