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author | peter <peter@FreeBSD.org> | 1997-05-12 12:13:10 +0000 |
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committer | peter <peter@FreeBSD.org> | 1997-05-12 12:13:10 +0000 |
commit | 650b3f23d13ecab9af9877809e54ede71d107b33 (patch) | |
tree | 02237a3132bd0ed3ee0acb4b44dfc50da133fcdb /lib/libc/sys/clock_gettime.2 | |
parent | a61579672e680c369e4b30f42dce84e944ce5006 (diff) | |
download | FreeBSD-src-650b3f23d13ecab9af9877809e54ede71d107b33.zip FreeBSD-src-650b3f23d13ecab9af9877809e54ede71d107b33.tar.gz |
Man pages for clock_{get/set}time() and clock_getres().
Obtained from: kstailey@openbsd.org via OpenBSD sources
Diffstat (limited to 'lib/libc/sys/clock_gettime.2')
-rw-r--r-- | lib/libc/sys/clock_gettime.2 | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/lib/libc/sys/clock_gettime.2 b/lib/libc/sys/clock_gettime.2 new file mode 100644 index 0000000..6894c14 --- /dev/null +++ b/lib/libc/sys/clock_gettime.2 @@ -0,0 +1,124 @@ +.\" $OpenBSD: clock_gettime.2,v 1.4 1997/05/08 20:21:16 kstailey Exp $ +.\" $Id$ +.\" +.\" Copyright (c) 1980, 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.Dd May 8, 1997 +.Dt CLOCK_GETTIME 2 +.Os BSD 4 +.Sh NAME +.Nm clock_gettime , +.Nm clock_settime , +.Nm clock_getres +.Nd get/set/calibrate date and time +.Sh SYNOPSIS +.Fd #include <sys/time.h> +.Ft int +.Fn clock_gettime "clockid_t clock_id" "struct timespec *tp" +.Ft int +.Fn clock_settime "clockid_t clock_id" "const struct timespec *tp" +.Ft int +.Fn clock_getres "clockid_t clock_id" "const struct timespec *tp" +.Sh DESCRIPTION +The +.Fn clock_gettime +and +.Fn clock_settime +allow the calling process to retrieve or set the value used by a clock +which is specifed by +.Fa clock_id . +.Pp +.Fa clock_id +can be one of three values: CLOCK_REALTIME for time that increments as +a wall clock should, CLOCK_VIRTUAL for time that increments only when +the CPU is running in user mode on behalf of the calling process, or +CLOCK_PROF for time that increments when the CPU is running in user or +kernel mode. +.Pp +The structure pointed to by +.Fa tp +is defined in +.Ao Pa sys/time.h Ac +as: +.Pp +.Bd -literal +struct timespec { + time_t tv_sec; /* seconds */ + long tv_nsec; /* and nanoseconds */ +}; +.Ed +.Pp +Only the super-user may set the time of day. +If the system securelevel is greater than 1 (see +.Xr init 8 ), +the time may only be advanced. +This limitation is imposed to prevent a malicious super-user +from setting arbitrary time stamps on files. +The system time can still be adjusted backwards using the +.Xr adjtime 2 +system call even when the system is secure. +.Pp +The resolution (granularity) of a clock is returned by the +.Fn clock_getres +call. This value is placed in a (non-NULL) +.Fa *tp . +.Sh RETURN +A 0 return value indicates that the call succeeded. +A -1 return value indicates an error occurred, and in this +case an error code is stored into the global variable +.Va errno . +.Sh ERRORS +The following error codes may be set in +.Va errno : +.Bl -tag -width [EFAULT] +.It Bq Er EINVAL +The +.Fa clock_id +was not a valid value. +.It Bq Er EFAULT +The +.Fa *tp +argument address referenced invalid memory. +.It Bq Er EPERM +A user other than the super-user attempted to set the time. +.El +.Sh SEE ALSO +.Xr date 1 , +.Xr adjtime 2 , +.Xr ctime 3 , +.Xr timed 8 +.Sh STANDARDS +The +.Fn clock_gettime , +etc. +functions conform to +.St -p1003.1b-93 . |