.\" $NetBSD: clock_settime.2,v 1.3 1999/02/16 19:36:52 kleink Exp $
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Klaus Klein.
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.Dd February 11, 1999
.Dt CLOCK_SETTIME 2
.Os NetBSD 1.3
.Sh NAME
.Nm clock_settime ,
.Nm clock_gettime ,
.Nm clock_getres
.Nd clock and timer functions
.Sh SYNOPSIS
.Fd #include <time.h>
.Ft int
.Fn clock_settime "clockid_t clock_id" "const struct timespec *tp"
.Ft int
.Fn clock_gettime "clockid_t clock_id" "struct timespec *tp"
.Ft int
.Fn clock_getres "clockid_t clock_id" "struct timespec *res"
.Sh DESCRIPTION
The
.Fn clock_settime
function sets the clock identified by
.Fa clock_id
to the absolute time specified by
.Fa tp .
If the time specified by
.Fa tp
is not a multiple of the resolution of the clock,
.Fa tp
is truncated to a multiple of the resolution.
.Pp
.The
.Fn clock_gettime
function stores the time of the clock identified by
.Fa clock_id
into the location specified by
.Fa tp.
.Pp
The
.Fn clock_getres
function stores the resolution of the clock identified by
.Fa clock_id
into the location specified by
.Fa res ,
unless
.Fa res
is
.Dv NULL .
.Pp
A
.Fa clock_id
of
.Dv CLOCK_REALTIME
identifies the realtime clock for the system.
For this clock, the values specified by
.Fn clock_settime
and obtained by
.Fn clock_gettime
represent the amount of time (in seconds and nanoseconds)
since 00:00 Universal Coordinated Time, January 1, 1970.
.Sh RETURN VALUES
A value of 0 is returned on success.  Otherwise, a value of -1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn clock_settime ,
.Fn clock_gettime
and
.Fn clock_getres
functions will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa clock_id
argument does not specify a known clock.
.It Bq Er ENOSYS
The function is not supported by this implementation.
.El
.Pp
The
.Fn clock_settime
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa tp
argument is outside the range for the specified clock,
.Fa clock_id .
.It Bq Er EINVAL
The
.Fa tp
argument specified a nanosecond value less than zero of greater than or equal
1000 million.
.It Bq Er EPERM
The
calling process does not have the appropriate privilege to set the specified
clock,
.Fa clock_id .
.El
.Pp
The
.Fn clock_gettime
function will fail if:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa tp
argument specifies an address that is not a valid part of the process address
space.
.El
.Sh SEE ALSO
.Xr ctime 3 ,
.Xr time 3
.\" .Xr timer_gettime 3
.Sh STANDARDS
The
.Fn clock_settime ,
.Fn clock_gettime
and
.Fn clock_getres
functions conform to
.St -p1003.1b-93 .