1 /* MIT License
2 *
3 * Copyright (c) 2008 Daniel Stenberg
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 *
24 * SPDX-License-Identifier: MIT
25 */
26
27 #include "ares_setup.h"
28 #include "ares.h"
29 #include "ares_private.h"
30
31 #if defined(WIN32) && !defined(MSDOS)
32
ares__tvnow(void)33 struct timeval ares__tvnow(void)
34 {
35 /*
36 ** GetTickCount() is available on _all_ Windows versions from W95 up
37 ** to nowadays. Returns milliseconds elapsed since last system boot,
38 ** increases monotonically and wraps once 49.7 days have elapsed.
39 */
40 struct timeval now;
41 DWORD milliseconds = GetTickCount();
42 now.tv_sec = (long)milliseconds / 1000;
43 now.tv_usec = (long)(milliseconds % 1000) * 1000;
44 return now;
45 }
46
47 #elif defined(HAVE_CLOCK_GETTIME_MONOTONIC)
48
ares__tvnow(void)49 struct timeval ares__tvnow(void)
50 {
51 /*
52 ** clock_gettime() is granted to be increased monotonically when the
53 ** monotonic clock is queried. Time starting point is unspecified, it
54 ** could be the system start-up time, the Epoch, or something else,
55 ** in any case the time starting point does not change once that the
56 ** system has started up.
57 */
58 struct timeval now;
59 struct timespec tsnow;
60 if (0 == clock_gettime(CLOCK_MONOTONIC, &tsnow)) {
61 now.tv_sec = tsnow.tv_sec;
62 now.tv_usec = (int)(tsnow.tv_nsec / 1000);
63 }
64 /*
65 ** Even when the configure process has truly detected monotonic clock
66 ** availability, it might happen that it is not actually available at
67 ** run-time. When this occurs simply fallback to other time source.
68 */
69 # ifdef HAVE_GETTIMEOFDAY
70 else
71 (void)gettimeofday(&now, NULL); /* LCOV_EXCL_LINE */
72 # else
73 else {
74 now.tv_sec = (long)time(NULL);
75 now.tv_usec = 0;
76 }
77 # endif
78 return now;
79 }
80
81 #elif defined(HAVE_GETTIMEOFDAY)
82
ares__tvnow(void)83 struct timeval ares__tvnow(void)
84 {
85 /*
86 ** gettimeofday() is not granted to be increased monotonically, due to
87 ** clock drifting and external source time synchronization it can jump
88 ** forward or backward in time.
89 */
90 struct timeval now;
91 (void)gettimeofday(&now, NULL);
92 return now;
93 }
94
95 #else
96
ares__tvnow(void)97 struct timeval ares__tvnow(void)
98 {
99 /*
100 ** time() returns the value of time in seconds since the Epoch.
101 */
102 struct timeval now;
103 now.tv_sec = (long)time(NULL);
104 now.tv_usec = 0;
105 return now;
106 }
107
108 #endif
109