| 1 | /* Provide gettimeofday for systems that don't have it or for which it's broken. |
| 2 | |
| 3 | Copyright (C) 2001-2003, 2005-2007, 2009-2020 Free Software Foundation, Inc. |
| 4 | |
| 5 | This program is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 3, or (at your option) |
| 8 | any later version. |
| 9 | |
| 10 | This program 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 General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU 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 | #include "localtime-buffer.h" |
| 33 | |
| 34 | #ifdef WINDOWS_NATIVE |
| 35 | |
| 36 | /* Avoid warnings from gcc -Wcast-function-type. */ |
| 37 | # define GetProcAddress \ |
| 38 | (void *) GetProcAddress |
| 39 | |
| 40 | /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */ |
| 41 | typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime); |
| 42 | static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL; |
| 43 | static BOOL initialized = FALSE; |
| 44 | |
| 45 | static void |
| 46 | initialize (void) |
| 47 | { |
| 48 | HMODULE kernel32 = LoadLibrary ("kernel32.dll"); |
| 49 | if (kernel32 != NULL) |
| 50 | { |
| 51 | GetSystemTimePreciseAsFileTimeFunc = |
| 52 | (GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime"); |
| 53 | } |
| 54 | initialized = TRUE; |
| 55 | } |
| 56 | |
| 57 | #endif |
| 58 | |
| 59 | /* This is a wrapper for gettimeofday. It is used only on systems |
| 60 | that lack this function, or whose implementation of this function |
| 61 | causes problems. |
| 62 | Work around the bug in some systems whereby gettimeofday clobbers |
| 63 | the static buffer that localtime uses for its return value. The |
| 64 | gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has |
| 65 | this problem. */ |
| 66 | |
| 67 | int |
| 68 | gettimeofday (struct timeval *restrict tv, void *restrict tz) |
| 69 | { |
| 70 | #undef gettimeofday |
| 71 | #ifdef WINDOWS_NATIVE |
| 72 | |
| 73 | /* On native Windows, there are two ways to get the current time: |
| 74 | GetSystemTimeAsFileTime |
| 75 | <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime> |
| 76 | or |
| 77 | GetSystemTimePreciseAsFileTime |
| 78 | <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime>. |
| 79 | GetSystemTimeAsFileTime produces values that jump by increments of |
| 80 | 15.627 milliseconds (!) on average. |
| 81 | Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2 |
| 82 | microseconds. |
| 83 | More discussion on this topic: |
| 84 | <http://www.windowstimestamp.com/description>. */ |
| 85 | FILETIME current_time; |
| 86 | |
| 87 | if (!initialized) |
| 88 | initialize (); |
| 89 | if (GetSystemTimePreciseAsFileTimeFunc != NULL) |
| 90 | GetSystemTimePreciseAsFileTimeFunc (¤t_time); |
| 91 | else |
| 92 | GetSystemTimeAsFileTime (¤t_time); |
| 93 | |
| 94 | /* Convert from FILETIME to 'struct timeval'. */ |
| 95 | /* FILETIME: <https://docs.microsoft.com/en-us/windows/desktop/api/minwinbase/ns-minwinbase-filetime> */ |
| 96 | ULONGLONG since_1601 = |
| 97 | ((ULONGLONG) current_time.dwHighDateTime << 32) |
| 98 | | (ULONGLONG) current_time.dwLowDateTime; |
| 99 | /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap |
| 100 | years, in total 134774 days. */ |
| 101 | ULONGLONG since_1970 = |
| 102 | since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000; |
| 103 | ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10; |
| 104 | tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000; |
| 105 | tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000; |
| 106 | |
| 107 | return 0; |
| 108 | |
| 109 | #else |
| 110 | |
| 111 | # if HAVE_GETTIMEOFDAY |
| 112 | # if GETTIMEOFDAY_CLOBBERS_LOCALTIME |
| 113 | /* Save and restore the contents of the buffer used for localtime's |
| 114 | result around the call to gettimeofday. */ |
| 115 | struct tm save = *localtime_buffer_addr; |
| 116 | # endif |
| 117 | |
| 118 | # if defined timeval /* 'struct timeval' overridden by gnulib? */ |
| 119 | # undef timeval |
| 120 | struct timeval otv; |
| 121 | int result = gettimeofday (&otv, (struct timezone *) tz); |
| 122 | if (result == 0) |
| 123 | { |
| 124 | tv->tv_sec = otv.tv_sec; |
| 125 | tv->tv_usec = otv.tv_usec; |
| 126 | } |
| 127 | # else |
| 128 | int result = gettimeofday (tv, (struct timezone *) tz); |
| 129 | # endif |
| 130 | |
| 131 | # if GETTIMEOFDAY_CLOBBERS_LOCALTIME |
| 132 | *localtime_buffer_addr = save; |
| 133 | # endif |
| 134 | |
| 135 | return result; |
| 136 | |
| 137 | # else |
| 138 | |
| 139 | # if !defined OK_TO_USE_1S_CLOCK |
| 140 | # error "Only 1-second nominal clock resolution found. Is that intended?" \ |
| 141 | "If so, compile with the -DOK_TO_USE_1S_CLOCK option." |
| 142 | # endif |
| 143 | tv->tv_sec = time (NULL); |
| 144 | tv->tv_usec = 0; |
| 145 | |
| 146 | return 0; |
| 147 | |
| 148 | # endif |
| 149 | #endif |
| 150 | } |