1/*	$OpenBSD: time.c,v 1.5 2005/08/08 08:05:34 espie Exp $ */
2/*
3 * Copyright (c) 1983, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <time.h>
32
33time_t
34time(time_t *t)
35{
36	struct timeval tt;
37	time_t ret;
38
39	if (gettimeofday(&tt, (struct timezone *)0) < 0)
40		ret = -1;
41	else
42		ret = tt.tv_sec;
43	if (t != NULL)
44		*t = ret;
45	return ret;
46}
47
48// return monotonically increasing CPU time in ticks relative to unspecified epoch
49static inline clock_t clock_now(void)
50{
51	struct timespec tm;
52	clock_gettime( CLOCK_MONOTONIC, &tm);
53	return tm.tv_sec * CLOCKS_PER_SEC + (tm.tv_nsec * (CLOCKS_PER_SEC/1e9));
54}
55
56// initialized by the constructor below
57static clock_t clock_start;
58
59// called by dlopen when .so is loaded
60__attribute__((constructor)) static void clock_crt0(void)
61{
62	clock_start = clock_now();
63}
64
65// return elapsed CPU time in clock ticks, since start of program execution
66// (spec says epoch is undefined, but glibc uses crt0 as epoch)
67clock_t
68clock(void)
69{
70	// note that if we are executing in a different thread than crt0, then the
71	// pthread_create that made us had a memory barrier so clock_start is defined
72	return clock_now() - clock_start;
73}
74