On Tue, Apr 20, 2010 at 12:41 PM, Ozkan Sezer <[email protected]> wrote: > On Tue, Apr 20, 2010 at 7:37 AM, Kai Tietz <[email protected]> wrote: >> Hi Patrick, >> >> 2010/4/20 Patrick Galbraith <[email protected]>: >>> Hi all, >>> >>> I've stumbled across an issue with gettimeofday() returning an incorrect >>> value with mingw-w64. A simple code sample: >>> >>> #include <stdio.h> >>> #include <sys/time.h> >>> >>> int main (void) >>> { >>> struct timeval timer; >>> int retval; >>> retval= gettimeofday(&timer,NULL); >>> fprintf(stderr, "retval: %d\n", retval); >>> fprintf(stderr, "now: %ld\n", time(0)); >>> fprintf(stderr, "now: %ld\n", timer.tv_sec); >>> return(0); >>> >>> } >>> >>> When compiled using - >>> >>> regular mingw (correct output) >>> >>> Patrick galbra...@win-7a3e68a2d98 ~/dev/stuff >>> $ gcc -o mtime mtime.c >>> >>> Patrick galbra...@win-7a3e68a2d98 ~/dev/stuff >>> $ ./mtime.exe >>> retval: 0 >>> now: 1271722468 >>> now: 1271722468 >>> >>> mingw-w64: >>> >>> >>> Patrick galbra...@win-7a3e68a2d98 ~/dev/stuff >>> $ /c/mingw/bin/x86_64-w64-mingw32-gcc -o mtime mtime.c >>> >>> Patrick galbra...@win-7a3e68a2d98 ~/dev/stuff >>> $ ./mtime.exe >>> retval: 0 >>> now: 1271722480 >>> now: 31293027 >>> >>> Are there any known issues with gettimeofday() with mingw-w64? >>> >>> Thanks! >>> >>> Patrick >> >> what you are seeing here is that time_t type has changed for x64. x64 >> doesn't use any longer a 32-bit time_t type. I use 64-bit wide scalar >> instead. >> If you want to have 32-bit time_t the use please the <timefunction>32 >> function set and use instead tim32_t type. >> >> Regards, >> Kai > > I can't see the use of a time_t type anywhere in the report? > Is there a misunderstanding somewhere? > > The problem may be due to strict aliasing violations. > A warning doesn't appear with default CFLAGS, but > after adding -Wstrict-aliasing=2, you get > > gettimeofday.c: In function 'getntptimeofday': > gettimeofday.c:42: warning: dereferencing type-punned pointer will > break strict-aliasing rules > > The mingw.org version of gettimeofday.c doesn't exhibit > such an issue. Proper use of a union as it the mingw.org > version might be a solution. > > -- > Ozkan >
Hmm, changing the FILETIME_1970 macro from 11644473600ull to 116444736000000000ULL in gettimeofday.c as in the mingw.org version seems to make the testcase output the same value. Kai, is this correct? (see attached g3.diff.) Please verify. -- Ozkan
g3.diff
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