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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Not sure whether it is related to mktime (see also <a href="http://mm.icann.org/pipermail/tz/2017-January/thread.html#24749">
http://mm.icann.org/pipermail/tz/2017-January/thread.html#24749</a>), but I run into a similar issue.<o:p></o:p></p>
<p class="MsoNormal">Consider the code below, and compile with (any) tz library (I tried with 2017A code). Save the source and compile with:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">gcc -o <out> <source> -L <tzdir> -ltz<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Running the produced exe results in:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">gcc -o ambigioustest2017a ambigioustest.c -L./tzcode2017a/ -ltz<o:p></o:p></p>
<p class="MsoNormal">kdekker@nlbavlsm3.infor.com:/home/kdekker/downloads$ ./ambigioustest2017a<o:p></o:p></p>
<p class="MsoNormal">enter mktime with: 1970/Jan/15278 00:119:30, week day: -858993460, year day: -858993460, dst: -1<o:p></o:p></p>
<p class="MsoNormal">the return value of mktime is: 1319957970<o:p></o:p></p>
<p class="MsoNormal">normalized times: 2011/Oct/30 01:59:30, week day: Sun, year day: 302, dst: 0<o:p></o:p></p>
<p class="MsoNormal">tz=EST, EDT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Based on the provided TZ value, I expected that 01:59:30 is still in DST, and thus the returned value by mktime should be 1319954370 (i.e. one hour off).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What I’m doing wrong, or what is wrong in the mktime() code?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please not that running the same source by using the built-in glibc mktime() function (i.e. gcc -o <exe> <sourcefile> and no additional flags), the result changes to:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">enter mktime with: 1970/Jan/15278 00:119:30, week day: -858993460, year day: -858993460, dst: -1<o:p></o:p></p>
<p class="MsoNormal">the return value of mktime is: 1319954370<o:p></o:p></p>
<p class="MsoNormal">normalized times: 2011/Oct/30 01:59:30, week day: Sun, year day: 302, dst: 1<o:p></o:p></p>
<p class="MsoNormal">tz=EST, EDT<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Note the minor differences with the previous output.<o:p></o:p></p>
<p class="MsoNormal">Please let me know what should be correct?<o:p></o:p></p>
<p class="MsoNormal">The provided source code is a part of our larger own test suite. Our test suite tests a wide range of values, especially near boundaries or ambiguous values.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">Kees<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/* start C-code */<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">#include <time.h><o:p></o:p></p>
<p class="MsoNormal">#include <stdio.h><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">int main(void)<o:p></o:p></p>
<p class="MsoNormal">{<o:p></o:p></p>
<p class="MsoNormal"> int ret = 0;<o:p></o:p></p>
<p class="MsoNormal"> const char *months[] = { "Jan", "Feb", "Mar", "April", "May", "June", "July", "Aug", "Sep", "Oct", "Nov", "Dec" };<o:p></o:p></p>
<p class="MsoNormal"> const char *days[] = { "Sun", "Mon", "Tue", "Wed", "Tur", "Fri", "Sat" };<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> // Back from daylight saving time to normal time.<o:p></o:p></p>
<p class="MsoNormal"> // In 2011, this happened October 30.<o:p></o:p></p>
<p class="MsoNormal"> // At 03:00 hours, local time was set back one hour.<o:p></o:p></p>
<p class="MsoNormal"> // So local time interval 02:00 - 03:00 hours is ambiguous:<o:p></o:p></p>
<p class="MsoNormal"> // It exists both in dayligth saving time and in normal time.<o:p></o:p></p>
<p class="MsoNormal"> putenv("TZ=EST5EDT,M4.1.0/02:00,M10.5.0/02:00");<o:p></o:p></p>
<p class="MsoNormal"> struct tm tmp = { 30, 119, 0, 15278, 0, 70, -858993460, -858993460, -1};<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> printf("enter mktime with: %04d/%s/%02d %02d:%02d:%02d, week day: %d, year day: %d, dst: %d\n",
<o:p></o:p></p>
<p class="MsoNormal"> tmp.tm_year + 1900, months[tmp.tm_mon], tmp.tm_mday,<o:p></o:p></p>
<p class="MsoNormal"> tmp.tm_hour, tmp.tm_min, tmp.tm_sec,
<o:p></o:p></p>
<p class="MsoNormal"> tmp.tm_wday, tmp.tm_yday, tmp.tm_isdst);<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> time_t t = mktime(&tmp);<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> /* expect: t == 1319954370, DST is still on, because it still some seconds before 2:00 */<o:p></o:p></p>
<p class="MsoNormal"> printf("the return value of mktime is: %lld\n", (long long)t);<o:p></o:p></p>
<p class="MsoNormal"> printf("normalized times: %04d/%s/%02d %02d:%02d:%02d, week day: %s, year day: %d, dst: %d\n",
<o:p></o:p></p>
<p class="MsoNormal"> tmp.tm_year + 1900, months[tmp.tm_mon], tmp.tm_mday,<o:p></o:p></p>
<p class="MsoNormal"> tmp.tm_hour, tmp.tm_min, tmp.tm_sec,
<o:p></o:p></p>
<p class="MsoNormal"> days[tmp.tm_wday], tmp.tm_yday, tmp.tm_isdst);<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> if (t >= 0) {<o:p></o:p></p>
<p class="MsoNormal"> printf("tz=%s, %s\n", tzname[0], tzname[1]);<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> return 0;<o:p></o:p></p>
<p class="MsoNormal">}<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/* End-of-C-Code */<o:p></o:p></p>
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