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
33 time_t
time(time_t * t)34 time(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
clock_now(void)49 static 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
57 static clock_t clock_start;
58
59 // called by dlopen when .so is loaded
clock_crt0(void)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)
67 clock_t
clock(void)68 clock(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