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 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 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 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 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