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- /* Provide gettimeofday for systems that don't have it or for which it's broken.
- Copyright (C) 2001-2003, 2005-2007, 2009-2021 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program; if not, see <https://www.gnu.org/licenses/>. */
- /* written by Jim Meyering */
- #include <config.h>
- /* Specification. */
- #include <sys/time.h>
- #include <time.h>
- #if defined _WIN32 && ! defined __CYGWIN__
- # define WINDOWS_NATIVE
- # include <windows.h>
- #endif
- #ifdef WINDOWS_NATIVE
- /* Don't assume that UNICODE is not defined. */
- # undef LoadLibrary
- # define LoadLibrary LoadLibraryA
- # if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
- /* Avoid warnings from gcc -Wcast-function-type. */
- # define GetProcAddress \
- (void *) GetProcAddress
- /* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */
- typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime);
- static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL;
- static BOOL initialized = FALSE;
- static void
- initialize (void)
- {
- HMODULE kernel32 = LoadLibrary ("kernel32.dll");
- if (kernel32 != NULL)
- {
- GetSystemTimePreciseAsFileTimeFunc =
- (GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime");
- }
- initialized = TRUE;
- }
- # else
- # define GetSystemTimePreciseAsFileTimeFunc GetSystemTimePreciseAsFileTime
- # endif
- #endif
- /* This is a wrapper for gettimeofday. It is used only on systems
- that lack this function, or whose implementation of this function
- causes problems.
- Work around the bug in some systems whereby gettimeofday clobbers
- the static buffer that localtime uses for its return value. The
- gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
- this problem. */
- int
- gettimeofday (struct timeval *restrict tv, void *restrict tz)
- {
- #undef gettimeofday
- #ifdef WINDOWS_NATIVE
- /* On native Windows, there are two ways to get the current time:
- GetSystemTimeAsFileTime
- <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime>
- or
- GetSystemTimePreciseAsFileTime
- <https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime>.
- GetSystemTimeAsFileTime produces values that jump by increments of
- 15.627 milliseconds (!) on average.
- Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2
- microseconds.
- More discussion on this topic:
- <http://www.windowstimestamp.com/description>. */
- FILETIME current_time;
- # if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
- if (!initialized)
- initialize ();
- # endif
- if (GetSystemTimePreciseAsFileTimeFunc != NULL)
- GetSystemTimePreciseAsFileTimeFunc (¤t_time);
- else
- GetSystemTimeAsFileTime (¤t_time);
- /* Convert from FILETIME to 'struct timeval'. */
- /* FILETIME: <https://docs.microsoft.com/en-us/windows/desktop/api/minwinbase/ns-minwinbase-filetime> */
- ULONGLONG since_1601 =
- ((ULONGLONG) current_time.dwHighDateTime << 32)
- | (ULONGLONG) current_time.dwLowDateTime;
- /* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
- years, in total 134774 days. */
- ULONGLONG since_1970 =
- since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000;
- ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10;
- tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000;
- tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000;
- return 0;
- #else
- # if HAVE_GETTIMEOFDAY
- # if defined timeval /* 'struct timeval' overridden by gnulib? */
- # undef timeval
- struct timeval otv;
- int result = gettimeofday (&otv, (struct timezone *) tz);
- if (result == 0)
- {
- tv->tv_sec = otv.tv_sec;
- tv->tv_usec = otv.tv_usec;
- }
- # else
- int result = gettimeofday (tv, (struct timezone *) tz);
- # endif
- return result;
- # else
- # if !defined OK_TO_USE_1S_CLOCK
- # error "Only 1-second nominal clock resolution found. Is that intended?" \
- "If so, compile with the -DOK_TO_USE_1S_CLOCK option."
- # endif
- tv->tv_sec = time (NULL);
- tv->tv_usec = 0;
- return 0;
- # endif
- #endif
- }
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