154 lines
4.7 KiB
C
154 lines
4.7 KiB
C
/* Provide gettimeofday for systems that don't have it or for which it's broken.
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Copyright (C) 2001-2003, 2005-2007, 2009-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* written by Jim Meyering */
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#include <config.h>
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/* Specification. */
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#include <sys/time.h>
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#include <time.h>
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#if defined _WIN32 && ! defined __CYGWIN__
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# define WINDOWS_NATIVE
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# include <windows.h>
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#endif
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#ifdef WINDOWS_NATIVE
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/* Don't assume that UNICODE is not defined. */
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# undef LoadLibrary
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# define LoadLibrary LoadLibraryA
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# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
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/* Avoid warnings from gcc -Wcast-function-type. */
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# define GetProcAddress \
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(void *) GetProcAddress
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/* GetSystemTimePreciseAsFileTime was introduced only in Windows 8. */
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typedef void (WINAPI * GetSystemTimePreciseAsFileTimeFuncType) (FILETIME *lpTime);
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static GetSystemTimePreciseAsFileTimeFuncType GetSystemTimePreciseAsFileTimeFunc = NULL;
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static BOOL initialized = FALSE;
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static void
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initialize (void)
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{
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HMODULE kernel32 = LoadLibrary ("kernel32.dll");
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if (kernel32 != NULL)
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{
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GetSystemTimePreciseAsFileTimeFunc =
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(GetSystemTimePreciseAsFileTimeFuncType) GetProcAddress (kernel32, "GetSystemTimePreciseAsFileTime");
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}
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initialized = TRUE;
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}
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# else
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# define GetSystemTimePreciseAsFileTimeFunc GetSystemTimePreciseAsFileTime
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# endif
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#endif
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/* This is a wrapper for gettimeofday. It is used only on systems
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that lack this function, or whose implementation of this function
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causes problems.
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Work around the bug in some systems whereby gettimeofday clobbers
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the static buffer that localtime uses for its return value. The
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gettimeofday function from Mac OS X 10.0.4 (i.e., Darwin 1.3.7) has
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this problem. */
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int
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gettimeofday (struct timeval *restrict tv, void *restrict tz)
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{
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#undef gettimeofday
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#ifdef WINDOWS_NATIVE
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/* On native Windows, there are two ways to get the current time:
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GetSystemTimeAsFileTime
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<https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime>
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or
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GetSystemTimePreciseAsFileTime
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<https://docs.microsoft.com/en-us/windows/desktop/api/sysinfoapi/nf-sysinfoapi-getsystemtimepreciseasfiletime>.
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GetSystemTimeAsFileTime produces values that jump by increments of
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15.627 milliseconds (!) on average.
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Whereas GetSystemTimePreciseAsFileTime values usually jump by 1 or 2
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microseconds.
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More discussion on this topic:
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<http://www.windowstimestamp.com/description>. */
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FILETIME current_time;
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# if !(_WIN32_WINNT >= _WIN32_WINNT_WIN8)
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if (!initialized)
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initialize ();
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# endif
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if (GetSystemTimePreciseAsFileTimeFunc != NULL)
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GetSystemTimePreciseAsFileTimeFunc (¤t_time);
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else
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GetSystemTimeAsFileTime (¤t_time);
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/* Convert from FILETIME to 'struct timeval'. */
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/* FILETIME: <https://docs.microsoft.com/en-us/windows/desktop/api/minwinbase/ns-minwinbase-filetime> */
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ULONGLONG since_1601 =
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((ULONGLONG) current_time.dwHighDateTime << 32)
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| (ULONGLONG) current_time.dwLowDateTime;
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/* Between 1601-01-01 and 1970-01-01 there were 280 normal years and 89 leap
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years, in total 134774 days. */
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ULONGLONG since_1970 =
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since_1601 - (ULONGLONG) 134774 * (ULONGLONG) 86400 * (ULONGLONG) 10000000;
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ULONGLONG microseconds_since_1970 = since_1970 / (ULONGLONG) 10;
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tv->tv_sec = microseconds_since_1970 / (ULONGLONG) 1000000;
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tv->tv_usec = microseconds_since_1970 % (ULONGLONG) 1000000;
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return 0;
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#else
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# if HAVE_GETTIMEOFDAY
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# if defined timeval /* 'struct timeval' overridden by gnulib? */
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# undef timeval
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struct timeval otv;
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int result = gettimeofday (&otv, (struct timezone *) tz);
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if (result == 0)
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{
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tv->tv_sec = otv.tv_sec;
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tv->tv_usec = otv.tv_usec;
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}
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# else
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int result = gettimeofday (tv, (struct timezone *) tz);
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# endif
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return result;
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# else
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# if !defined OK_TO_USE_1S_CLOCK
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# error "Only 1-second nominal clock resolution found. Is that intended?" \
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"If so, compile with the -DOK_TO_USE_1S_CLOCK option."
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# endif
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tv->tv_sec = time (NULL);
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tv->tv_usec = 0;
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return 0;
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# endif
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#endif
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}
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