CLOCK_SETTIME(2) | System Calls Manual | CLOCK_SETTIME(2) |
clock_settime
, clock_gettime
,
clock_getres
—
#include <time.h>
int
clock_settime
(clockid_t
clock_id, const struct
timespec *tp);
int
clock_gettime
(clockid_t
clock_id, struct timespec
*tp);
int
clock_getres
(clockid_t
clock_id, struct timespec
*res);
clock_settime
() function sets the clock identified
by clock_id to the absolute time specified by
tp. If the time specified by tp is
not a multiple of the resolution of the clock, tp is
truncated to a multiple of the resolution.
The clock_gettime
() function stores the
time of the clock identified by clock_id into the
location specified by tp.
The clock_getres
() function stores the
resolution of the clock identified by clock_id into
the location specified by res, unless
res is NULL
.
The following clock_id values are supported:
CLOCK_REALTIME
clock_settime
() and obtained by
clock_gettime
() represent the amount of time (in
seconds and nanoseconds) since 00:00 Universal Coordinated Time, January
1, 1970.CLOCK_MONOTONIC
EINVAL
error if it's the clock
specified in a call to clock_settime
(). The origin
of the clock is unspecified.CLOCK_VIRTUAL
CLOCK_PROF
CLOCK_PROCESS_CPUTIME_ID
CLOCK_THREAD_CPUTIME_ID
If the calling user is not the super-user, the
clock_settime
() system call will fail, and the
clock_settime
() function in the standard C library
will try to use the
clockctl(4) device if
present, thus making it possible for non privileged users to set the system
time. If clockctl(4) is not
present or not accessible, then clock_settime
()
returns EPERM
.
clock_settime
(),
clock_gettime
() and
clock_getres
() functions will fail if:
EINVAL
]ENOSYS
]The clock_settime
() function will fail
if:
EINVAL
]EPERM
]The clock_gettime
() function will fail
if:
EFAULT
]clock_settime
(),
clock_gettime
() and
clock_getres
() functions conform to
IEEE Std 1003.1b-1993 (“POSIX.1b”).
September 23, 2016 | NetBSD 9.2 |