[tz] Regarding changes of time format the Philippines

[Arati]

Thank you Paul and Zefram.

Well my bad i missed to update the code with seconds while calling 
localtime.

Even after that things didn't work for me.

_Code_

  cat test_tz_simple.c
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <syslog.h>

#include <sys/time.h> /* clude defn. of gettimeofday */
#include <sys/types.h>


int main()
{
u_int64_t time = 0;
struct timeval tv;
struct tm *tm;
int gmtoff, gmtoff_hr, gmtoff_min;
char *gmtoff_sign;

if ( gettimeofday(&tv, NULL) == 0)
{
      time = (long long) tv.tv_sec;

}

*tm = localtime(&tv.tv_sec);*
printf ("epoch:%lld, %lld-%02d-%02d %02d:%02d:%02d gmtoff: %ld, TZ: %s\n",
       time, tm->tm_year + 1900LL, tm->tm_mon + 1, tm->tm_mday,
       tm->tm_hour, tm->tm_min, tm->tm_sec,
       tm->tm_gmtoff, tm->tm_zone);

if ( tm->tm_gmtoff < 0 )
     {
         gmtoff = (0 - tm->tm_gmtoff );
         gmtoff_sign = "-";
     }
     else
     {
         gmtoff = tm->tm_gmtoff;
         gmtoff_sign = "+";
     }
gmtoff_hr = gmtoff/3600;
gmtoff_min = gmtoff/60 - gmtoff_hr*60;

printf("Time: %04d-%02d-%02d %02d:%02d:%02d.%03d %s%02d%02d \n",
                         (tm->tm_year + 1900), tm->tm_mon+1, tm->tm_mday,
                         tm->tm_hour, tm->tm_min, tm->tm_sec, time,
                         gmtoff_sign, gmtoff_hr, gmtoff_min);

}




Regarding setting TZ variable , we use customized linux platform. The 
way time zone is set is as follows

$ cat /etc/sysconfig/clock
UTC=true
ARC=false
ZONE=Asia/Manila

$ls -ltr /etc/localtime
lrwxrwxrwx 1 root root 31 Oct 26 12:31 /etc/localtime -> 
/usr/share/zoneinfo/Asia/Manila

I tried export TZ=Asia/Manila before running a.out. But no luck.

surprisingly, when i copy back 2016g version of tzdb binary, a.out gives 
correct result.

$ cksum /usr/share/zoneinfo/Asia/Manila_2016
2614106258 319 /usr/share/zoneinfo/Asia/Manila_2016


_Output with 2016g tzdb _

$ ./a.out
epoch:1509609002, 2017-11-02 15:50:02 gmtoff: 28800, TZ: PHT
Time: 2017-11-02 15:50:02.1509609002 +0800
$

$ cksum /usr/share/zoneinfo/Asia/Manila_2017
2995436782 311 /usr/share/zoneinfo/Asia/Manila_2017


_Output with 2017a tzdb _

$./a.out

epoch:1509608903, 2017-11-02 07:48:23 gmtoff: 0, TZ:
Time: 2017-11-02 07:48:23.1509608903 +0000

In fact recompiling 2017 tzdb  replacing *+08/+09 *by PH%sT for last row 
results in correct output.

Please advice.

Thanks & Regards,
Arati


On Thursday 02 November 2017 03:01 AM, Paul Eggert wrote:
> On 11/01/2017 01:12 PM, Zefram wrote:
>> localtime() operates on a time_t, the value of
>> which you need to get from time() or from the .tv_sec part of what you
>> get from gettimeofday().  Instead you've taken a correct .tv_sec and
>> multiplied it by 1000.  Instead of asking about November 2017 you've
>> asked about October 49804.  A zero offset is still not what the tzdb
>> projects for 49804, but localtime() can be forgiven for giving up.
>
> Although that is indeed a problem with the program, I suspect that 
> there's some other issue as well. I just now compiled and ran the 
> following simpler variant of the program on Fedora 26 x86-64 (64-bit 
> long and time_t), linked to the current tzdb code and data:
>
> #include <time.h>
> #include <stdio.h>
> int
> main (void)
> {
>   time_t time = 1509521131510;
>   long long ltime = time;
>   struct tm *tm = localtime (&time);
>   printf ("epoch:%lld, %lld-%02d-%02d %02d:%02d:%02d gmtoff: %ld, TZ: 
> %s\n",
>       ltime, tm->tm_year + 1900LL, tm->tm_mon + 1, tm->tm_mday,
>       tm->tm_hour, tm->tm_min, tm->tm_sec,
>       tm->tm_gmtoff, tm->tm_zone);
>   return 0;
> }
>
> With the TZ environment variable set to "Asia/Manila", it outputs the 
> expected value:
>
> epoch:1509521131510, 49804-10-27 17:25:10 gmtoff: 28800, TZ: +08
>
> With the TZ environment variable unset, it outputs:
>
> epoch:1509521131510, 49804-10-27 09:25:10 gmtoff: 0, TZ: GMT
>
> which are the reported symptoms. But the latter output is also 
> correct, since the default wall-clock time, if you just install tzdb 
> without any special configuration and do not set TZ, is the same as if 
> you had set TZ="GMT0".
>
>


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