1
2 /* Copyright (C) 2008 by Daniel Stenberg et al
3 *
4 * Permission to use, copy, modify, and distribute this software and its
5 * documentation for any purpose and without fee is hereby granted, provided
6 * that the above copyright notice appear in all copies and that both that
7 * copyright notice and this permission notice appear in supporting
8 * documentation, and that the name of M.I.T. not be used in advertising or
9 * publicity pertaining to distribution of the software without specific,
10 * written prior permission. M.I.T. makes no representations about the
11 * suitability of this software for any purpose. It is provided "as is"
12 * without express or implied warranty.
13 */
14
15 #include "ares_setup.h"
16 #include "ares.h"
17 #include "ares_private.h"
18
19 #if defined(WIN32) && !defined(MSDOS)
20
ares__tvnow(void)21 struct timeval ares__tvnow(void)
22 {
23 /*
24 ** GetTickCount() is available on _all_ Windows versions from W95 up
25 ** to nowadays. Returns milliseconds elapsed since last system boot,
26 ** increases monotonically and wraps once 49.7 days have elapsed.
27 */
28 struct timeval now;
29 DWORD milliseconds = GetTickCount();
30 now.tv_sec = milliseconds / 1000;
31 now.tv_usec = (milliseconds % 1000) * 1000;
32 return now;
33 }
34
35 #elif defined(HAVE_CLOCK_GETTIME_MONOTONIC)
36
ares__tvnow(void)37 struct timeval ares__tvnow(void)
38 {
39 /*
40 ** clock_gettime() is granted to be increased monotonically when the
41 ** monotonic clock is queried. Time starting point is unspecified, it
42 ** could be the system start-up time, the Epoch, or something else,
43 ** in any case the time starting point does not change once that the
44 ** system has started up.
45 */
46 struct timeval now;
47 struct timespec tsnow;
48 if(0 == clock_gettime(CLOCK_MONOTONIC, &tsnow)) {
49 now.tv_sec = tsnow.tv_sec;
50 now.tv_usec = tsnow.tv_nsec / 1000;
51 }
52 /*
53 ** Even when the configure process has truly detected monotonic clock
54 ** availability, it might happen that it is not actually available at
55 ** run-time. When this occurs simply fallback to other time source.
56 */
57 #ifdef HAVE_GETTIMEOFDAY
58 else
59 (void)gettimeofday(&now, NULL);
60 #else
61 else {
62 now.tv_sec = (long)time(NULL);
63 now.tv_usec = 0;
64 }
65 #endif
66 return now;
67 }
68
69 #elif defined(HAVE_GETTIMEOFDAY)
70
ares__tvnow(void)71 struct timeval ares__tvnow(void)
72 {
73 /*
74 ** gettimeofday() is not granted to be increased monotonically, due to
75 ** clock drifting and external source time synchronization it can jump
76 ** forward or backward in time.
77 */
78 struct timeval now;
79 (void)gettimeofday(&now, NULL);
80 return now;
81 }
82
83 #else
84
ares__tvnow(void)85 struct timeval ares__tvnow(void)
86 {
87 /*
88 ** time() returns the value of time in seconds since the Epoch.
89 */
90 struct timeval now;
91 now.tv_sec = (long)time(NULL);
92 now.tv_usec = 0;
93 return now;
94 }
95
96 #endif
97
98 #if 0 /* Not used */
99 /*
100 * Make sure that the first argument is the more recent time, as otherwise
101 * we'll get a weird negative time-diff back...
102 *
103 * Returns: the time difference in number of milliseconds.
104 */
105 long ares__tvdiff(struct timeval newer, struct timeval older)
106 {
107 return (newer.tv_sec-older.tv_sec)*1000+
108 (newer.tv_usec-older.tv_usec)/1000;
109 }
110 #endif
111
112