1 /*
2 * We also need to set the value high enough to signal inclusion of
3 * newer features (like clock_gettime). See the POSIX spec for more info:
4 * http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_02_01_02
5 *
6 * This file is Copyright (c) 2010-2018 by the GPSD project
7 * SPDX-License-Identifier: BSD-2-clause
8 */
9
10 #include "gpsd_config.h" /* must be before all includes */
11
12 #include <ctype.h>
13 #include <errno.h>
14 #include <math.h>
15 #include <stdio.h>
16 #include <stdlib.h>
17 #include <string.h>
18 #include <sys/time.h>
19 #include <time.h>
20
21 #include "timespec.h"
22
23 /* Convert a normalized timespec to a nice string
24 * put in it *buf, buf should be at least 22 bytes
25 *
26 * the returned buffer will look like, shortest case:
27 * sign character ' ' or '-'
28 * one digit of seconds
29 * decmal point '.'
30 * 9 digits of nanoSec
31 *
32 * So 12 chars, like this: "-0.123456789"
33 *
34 * Probable worst case is 10 digits of seconds,
35 * but standards do not provide hard limits to time_t
36 * So 21 characters like this: "-2147483647.123456789"
37 *
38 * date --date='@2147483647' is: Mon Jan 18 19:14:07 PST 2038
39 * date --date='@9999999999' is: Sat Nov 20 09:46:39 PST 2286
40 *
41 */
timespec_str(const struct timespec * ts,char * buf,size_t buf_size)42 const char *timespec_str(const struct timespec *ts, char *buf, size_t buf_size)
43 {
44 char sign = ' ';
45
46 if (!TS_GEZ(ts)) {
47 sign = '-';
48 }
49
50 /* %lld and (long long) because some time_t is bigger than a long
51 * mostly on 32-bit systems. */
52 (void)snprintf(buf, buf_size, "%c%lld.%09ld",
53 sign,
54 (long long)llabs(ts->tv_sec),
55 (long)labs(ts->tv_nsec));
56 return buf;
57 }
58
59 /* end */
60