1 /* Provide gettimeofday for systems that don't have it or for which it's broken. 2 3 Copyright (C) 2001-2003, 2005-2007, 2009-2022 Free Software Foundation, Inc. 4 5 This file is free software: you can redistribute it and/or modify 6 it under the terms of the GNU Lesser General Public License as 7 published by the Free Software Foundation; either version 2.1 of the 8 License, or (at your option) any later version. 9 10 This file is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 17 18 /* written by Jim Meyering */ 19 20 #include <config.h> 21 22 /* Specification. */ 23 #include <sys/time.h> 24 25 #include <time.h> 26 27 #if defined _WIN32 && ! defined __CYGWIN__ 28 # define WINDOWS_NATIVE 29 # include <windows.h> 30 #endif 31 32 #ifdef WINDOWS_NATIVE 33 34 /* Don't assume that UNICODE is not defined. */ 35 # undef LoadLibrary 36 # define LoadLibrary LoadLibraryA 37 38 # if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8) 39 40 /* Avoid warnings from gcc -Wcast-function-type. */ 41 # define GetProcAddress \ 42 (void *) GetProcAddress 43 44 /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */ 45 typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime); 46 static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL; 47 static BOOL initialized = FALSE; 48 49 static void 50 initialize (void) 51 { 52 HMODULE kernel32 = LoadLibrary ("kernel32.dll"); 53 if (kernel32 != NULL) 54 { 55 GetSystemTimePreciseAsFileTimeFunc = 56 (GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime"); 57 } 58 initialized = TRUE; 59 } 60 61 # else 62 63 # define GetSystemTimePreciseAsFileTimeFunc GetSystemTimePreciseAsFileTime 64 65 # endif 66 67 #endif 68 69 /* This is a wrapper for gettimeofday. It is used only on systems 70 that lack this function, or whose implementation of this function 71 causes problems. 72 Work around the bug in some systems whereby gettimeofday clobbers 73 the static buffer that localtime uses for its return value. The 74 gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has 75 this problem. */ 76 77 int 78 gettimeofday (struct timeval *restrict tv, void *restrict tz) 79 { 80 #undef gettimeofday 81 #ifdef WINDOWS_NATIVE 82 83 /* On native Windows, there are two ways to get the current time: 84 GetSystemTimeAsFileTime 85 <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime> 86 or 87 GetSystemTimePreciseAsFileTime 88 <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime>. 89 GetSystemTimeAsFileTime produces values that jump by increments of 90 15.627 milliseconds (!) on average. 91 Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2 92 microseconds. 93 More discussion on this topic: 94 <http://www.windowstimestamp.com/description>. */ 95 FILETIME current_time; 96 97 # if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8) 98 if (!initialized) 99 initialize (); 100 # endif 101 if (GetSystemTimePreciseAsFileTimeFunc != NULL) 102 GetSystemTimePreciseAsFileTimeFunc (¤t_time); 103 else 104 GetSystemTimeAsFileTime (¤t_time); 105 106 /* Convert from FILETIME to 'struct timeval'. */ 107 /* FILETIME: <https://docs.microsoft.com/en-us/windows/desktop/api/minwinbase/ns-minwinbase-filetime> */ 108 ULONGLONG since_1601 = 109 ((ULONGLONG) current_time.dwHighDateTime << 32) 110 | (ULONGLONG) current_time.dwLowDateTime; 111 /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap 112 years, in total 134774 days. */ 113 ULONGLONG since_1970 = 114 since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000; 115 ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10; 116 tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000; 117 tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000; 118 119 return 0; 120 121 #else 122 123 # if HAVE_GETTIMEOFDAY 124 125 # if defined timeval /* 'struct timeval' overridden by gnulib? */ 126 # undef timeval 127 struct timeval otv; 128 int result = gettimeofday (&otv, (struct timezone *) tz); 129 if (result == 0) 130 { 131 tv->tv_sec = otv.tv_sec; 132 tv->tv_usec = otv.tv_usec; 133 } 134 # else 135 int result = gettimeofday (tv, (struct timezone *) tz); 136 # endif 137 138 return result; 139 140 # else 141 142 # if !defined OK_TO_USE_1S_CLOCK 143 # error "Only 1-second nominal clock resolution found. Is that intended?" \ 144 "If so, compile with the -DOK_TO_USE_1S_CLOCK option." 145 # endif 146 tv->tv_sec = time (NULL); 147 tv->tv_usec = 0; 148 149 return 0; 150 151 # endif 152 #endif 153 } 154