On Wednesday 19 November 2025 23:12:11 Pali Rohár wrote:
> On Wednesday 19 November 2025 23:49:15 Martin Storsjö wrote:
> > On Wed, 19 Nov 2025, Pali Rohár wrote:
> >
> > > Thanks for input. I started writing new TZ=PST8PDT tests and I they are
> > > failing, seems like some another issue with _localtime64. I started
> > > debugging it and I figured out that the my test is failing even with the
> > > native CRT 32-bit locatime version on Windows XP.
> > >
> > > Here is the test:
> > >
> > > #include <stdio.h>
> > > #include <stdlib.h>
> > > #include <string.h>
> > > #include <time.h>
> > > #include <assert.h>
> > >
> > > #ifdef __GLIBC__
> > > typedef long int __time32_t;
> > > struct tm *_localtime32(const __time32_t *timep) { return
> > > localtime(&(time_t){*timep}); }
> > > __time32_t _mktime32(struct tm *tm) { return mktime(tm); }
> > > #endif
> > >
> > > int main() {
> > > __time32_t t32, t32_;
> > > struct tm *htm;
> > > struct tm tm2;
> > >
> > > putenv ("TZ=PST8PDT");
> > > tzset ();
> > >
> > > t32 = 1130661000; /* Sun Oct 30 08:30:00 UTC 2005 == Sun Oct 30 01:30:00
> > > PDT 2005 */
> > > htm = _localtime32 (&t32);
> > > tm2 = *htm;
> > > printf ("pacific _localtime32(%ld): sec=%d min=%d hour=%d mday=%d mon=%d
> > > year=%d wday=%d yday=%d isdst=%d\n",
> > > t32, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > > t32_ = _mktime32 (htm);
> > > printf ("pacific _mktime32(): %ld sec=%d min=%d hour=%d mday=%d mon=%d
> > > year=%d wday=%d yday=%d isdst=%d\n",
> > > t32_, htm->tm_sec, htm->tm_min, htm->tm_hour, htm->tm_mday,
> > > htm->tm_mon, htm->tm_year, htm->tm_wday, htm->tm_yday, htm->tm_isdst);
> > > fflush (stdout);
> > > assert (t32_ == t32);
> > > assert (memcmp (htm, &tm2, sizeof(tm2)) == 0);
> > >
> > > return 0;
> > > }
> > >
> > > On Windows XP when compiled with system os msvcrt.dll library it is
> > > failing with error:
> > >
> > > pacific _localtime32(1130661000): sec=0 min=30 hour=1 mday=30 mon=9
> > > year=105 wday=0 yday=302 isdst=1
> > > pacific _mktime32(): 1130664600 sec=0 min=30 hour=1 mday=30 mon=9
> > > year=105 wday=0 yday=302 isdst=0
> > > Assertion failed: t32_ == t32, file test.c, line 30
> > >
> >
> > Hmm, so it seems like _localtime32 does the right thing, but _mktime32 fails
> > to handle the daylight saving time aspect.
> >
> > > Do you have any idea what is wrong here? Bug in the msvcrt.dll or I have
> > > missed something in the test?
> >
> > I tested this on a Windows 11 machine, and there it does produce the right
> > result, so something seems to have changed in msvcrt.dll (or other system
> > components relating to this) between XP and 11.
> >
> > // Martin
>
> Ok, thanks for confirmation.
>
> I checked Windows 10 and its msvcrt.dll is working fine too.
> I checked also versioned msvcr* libs and 80-120 are working too.
> msvcr70 and older are broken.
>
> I will adjust test that with pre80 libs the mktime can return incorrect
> result.
I did another tests and seems that this issue was fixed in Vista
msvcrt.dll. On XP it is failing and in Vista it is passing.
Vista's system msvcrt.dll contains lot of new functions which were
introduced in versioned msvcr80.dll, so maybe this is reason why mktime
in Vista (and up) is working.
_______________________________________________
Mingw-w64-public mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
