xref: /illumos-gate/usr/src/man/man3head/time.h.3head (revision dea9f5e6)

.\"
.\" Sun Microsystems, Inc. gratefully acknowledges The Open Group for
.\" permission to reproduce portions of its copyrighted documentation.
.\" Original documentation from The Open Group can be obtained online at
.\" http://www.opengroup.org/bookstore/.
.\"
.\" The Institute of Electrical and Electronics Engineers and The Open
.\" Group, have given us permission to reprint portions of their
.\" documentation.
.\"
.\" In the following statement, the phrase ``this text'' refers to portions
.\" of the system documentation.
.\"
.\" Portions of this text are reprinted and reproduced in electronic form
.\" in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
.\" Standard for Information Technology -- Portable Operating System
.\" Interface (POSIX), The Open Group Base Specifications Issue 6,
.\" Copyright (C) 2001-2004 by the Institute of Electrical and Electronics
.\" Engineers, Inc and The Open Group.  In the event of any discrepancy
.\" between these versions and the original IEEE and The Open Group
.\" Standard, the original IEEE and The Open Group Standard is the referee
.\" document.  The original Standard can be obtained online at
.\" http://www.opengroup.org/unix/online.html.
.\"
.\" This notice shall appear on any product containing this material.
.\"
.\" The contents of this file are subject to the terms of the
.\" Common Development and Distribution License (the "License").
.\" You may not use this file except in compliance with the License.
.\"
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
.\" or http://www.opensolaris.org/os/licensing.
.\" See the License for the specific language governing permissions
.\" and limitations under the License.
.\"
.\" When distributing Covered Code, include this CDDL HEADER in each
.\" file and include the License file at usr/src/OPENSOLARIS.LICENSE.
.\" If applicable, add the following below this CDDL HEADER, with the
.\" fields enclosed by brackets "[]" replaced with your own identifying
.\" information: Portions Copyright [yyyy] [name of copyright owner]
.\"
.\"
.\" Copyright (c) 2001, The IEEE and The Open Group.  All Rights Reserved.
.\" Portions Copyright (c) 2008, Sun Microsystems, Inc. All Rights Reserved.
.\" Copyright 2016 Joyent, Inc.
.\" Copyright 2021 Oxide Computer Company
.\"
.Dd October 4, 2021
.Dt TIME.H 3HEAD
.Os
.Sh NAME
.Nm time.h ,
.Nm time
.Nd time types
.Sh SYNOPSIS
.In time.h
.Sh DESCRIPTION
The
.In time.h
header declares the structure
.Vt tm ,
which includes the following members:
.Bd -literal -offset indent
int tm_sec     /* seconds [0,60] */
int tm_min     /* minutes [0,59] */
int tm_hour    /* hour [0,23] */
int tm_mday    /* day of month [1,31] */
int tm_mon     /* month of year [0,11] */
int tm_year    /* years since 1900 */
int tm_wday    /* day of week [0,6] (Sunday =0) */
int tm_yday    /* day of year [0,365] */
int tm_isdst   /* daylight savings flag */
.Ed
.Pp
The value of
.Fa tm_isdst
is positive if Daylight Saving Time is in effect, 0 if Daylight Saving
Time is not in effect, and negative if the information is not available.
.Pp
The
.In time.h
header defines the following symbolic names:
.Bl -tag -width Ds
.It Dv CLOCK_MONOTONIC
The identifier for the system-wide monotonic clock, which is defined as a clock
whose value cannot be set with
.Fn clock_settime
and that cannot have backward clock jumps.
The maximum possible clock jump is implementation-defined.
See
.Xr clock_settime 3C .
.It Dv CLOCKS_PER_SEC
A number used to convert the value returned by the
.Fn clock
function into seconds.
See
.Xr clock 3C .
.It Dv CLOCK_PROCESS_CPUTIME_ID
The identifier of the CPU-time clock associated with the process making a
.Fn clock
or
.Fn timer_*
function call.
This clock includes both user and system CPU-time.
.It Dv CLOCK_REALTIME
The identifier of the system-wide realtime clock.
.It Dv CLOCK_THREAD_CPUTIME_ID
The identifier of the CPU-time clock associated with the thread making a
.Fn clock
or
.Fn timer_*
function call.
This clock includes both user and system CPU-time.
.It Dv CLOCK_VIRTUAL
The identifier of the CPU-time clock associated with the thread making a
.Fn clock
or
.Fn timer_*
function call.
This clock only includes user CPU-time.
.It Dv NULL
Null pointer constant.
.It Dv TIMER_ABSTIME
Flag indicating time is absolute.
For functions taking timer objects, this refers to the clock associated
with the timer.
.It Dv TIME_UTC
The identifier for the system-wide realtime clock with no time zone
translation.
Used in
.Fn timespec_get .
.El
.Pp
The
.In time.h
header declares the
.Vt timespec
structure, which has the following members:
.Bd -literal -offset indent
time_t tv_sec     /* seconds */
long   tv_nsec     /* nanoseconds */
.Ed
.Pp
The
.In time.h
header declares the
.Vt itimerspec
structure, which has the following members:
.Bd -literal -offset indent
struct timespec it_interval     /* timer period */
struct timespec it_value     /* timer expiration */
.Ed
.Pp
The
.Vt clock_t ,
.Vt size_t ,
.Vt time_t ,
.Vt clockid_t ,
and
.Vt timer_t
types are defined as described in
.In sys/types.h .
See
.Xr types.h 3HEAD .
.Pp
Although the value of
.Dv CLOCKS_PER_SEC
is required to be 1 million on all standard-conforming systems, it can
be variable on other systems, and it should not be assumed that
.Dv CLOCKS_PER_SEC
is a compile-time constant.
.Pp
The
.In time.h
header provides a declaration for
.Dv getdate_err .
.Pp
The following are declared as variables:
.Bd -literal -offset indent
extern int daylight;
extern long timezone;
extern char *tzname[];
.Ed
.Pp
Inclusion of the
.In time.h
header can make visible all symbols from the
.In signal.h
header.
.Sh USAGE
The range [0,60] for
.Fa tm_sec
allows for the occasional leap second.
.Pp
.Fa tm_year
is a signed value; therefore, years before 1900 can be represented.
.Pp
To obtain the number of clock ticks per second returned by the
.Fn times
function, applications should call
.Fn sysconf "_SC_CLK_TCK" .
See
.Xr times 2
and
.Xr sysconf 3C .
.Sh INTERFACE STABILITY
.Sy Committed
.Sh SEE ALSO
.Xr time 2 ,
.Xr utime 2 ,
.Xr clock 3C ,
.Xr clock_settime 3C ,
.Xr ctime 3C ,
.Xr difftime 3C ,
.Xr getdate 3C ,
.Xr mktime 3C ,
.Xr nanosleep 3C ,
.Xr strftime 3C ,
.Xr strptime 3C ,
.Xr timer_create 3C ,
.Xr timer_delete 3C ,
.Xr timer_settime 3C ,
.Xr timespec_get 3C ,
.Xr types.h 3HEAD ,
.Xr attributes 5 ,
.Xr standards 5