[tz] Regarding changes of time format the Philippines

[Arati Sethy]

Thank you Paul for a quick response.  When i set time_zone=>local, the perl prints correct time.
[root at 10.36.68.133] # ll /etc/localtime 
lrwxrwxrwx 1 root root 31 Oct 26 12:31 /etc/localtime -> /usr/share/zoneinfo/Asia/Manila
[root at 10.36.68.133] # cat test_tz.pl 
use DateTime;

my $dt = DateTime->now();
print "The current date and time : ", $dt->strftime('%Y-%m-%d %T %z')."\n";

my $dt = DateTime->now(time_zone=>"local");
print "The current date and time : ", $dt->strftime('%Y-%m-%d %T %z')."\n";
my $date = `date`;
print "$date \n";

[root at 10.36.68.133] # 
[root at 10.36.68.133] # perl test_tz.pl 
The current date and time : 2017-11-01 06:55:35 +0000
The current date and time : 2017-11-01 14:55:35 +0800
Wed Nov  1 14:55:35 +08 2017
 
[root at 10.36.68.133] #

Our main concern is we take epoch time and call unix localtime to translate the epoch time to local time. This is done in c which is giving wrong result now.

c code looks as follows

#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <syslog.h>

#include <sys/time.h> /* clude defn. of gettimeofday */
#include <sys/types.h>
u_int64_t sysMilliTime()
{
    struct timeval tv;
    u_int64_t timestamp = 0;

    if ( gettimeofday(&tv, NULL) == 0)
    {
        /* seconds elapsed since jan 1, 1970 */
        timestamp = (long long) tv.tv_sec;

        /* Convert into milli seconds */
        timestamp *= 1000;
        timestamp += tv.tv_usec/1000;
    }
    return timestamp;
}
int main()
{
u_int64_t time = sysMilliTime();
struct tm *evTime;
evTime = localtime(&time);
printf("epoch:%lld, gmtoff: %ld, TZ: %s\n",time,evTime->tm_gmtoff, evTime->tm_zone);
}

[root at 10.36.68.133] # ./a.out 
epoch:1509521131510, gmtoff: 0, TZ: 

[root at 10.36.68.133] # gcc -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.3.2/configure --prefix=/opt/gcc-4.3.2 --libdir=/opt/gcc-4.3.2/lib64 --libexecdir=/opt/gcc-4.3.2/lib64 --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-c99 --enable-long-long --enable-clocale=gnu --enable-languages=c,c++ --disable-libstdcxx-pch
Thread model: posix
gcc version 4.3.2 (GCC) 
[root at 10.36.68.133] # 

Please have a look and let me know your findings.

Thanks,
Arati
________________________________________
From: Paul Eggert <eggert at cs.ucla.edu>
Sent: Wednesday, November 1, 2017 12:03 AM
To: Arati Sethy
Cc: Time Zone Mailing List
Subject: Re: Regarding changes of time format the Philippines

I am not observing either problem on Fedora 26, which currently uses
tzdb 2017b and Perl 5.24.3. I ran the following shell commands. Please
try them on your platform. If they work for you, can you give examples
of similar shell commands that fail for you?

$ TZ=Asia/Manila date
Wed Nov  1 01:52:50 +08 2017
$ TZ=Asia/Manila perl -E'use DateTime; say
DateTime->now(time_zone=>"local")->strftime("%Y-%m-%d %H:%M:%S %z (%Z)");'
2017-11-01 01:53:22 +0800 (+08)
$ perl -E'use DateTime; say DateTime->VERSION;'
1.43
$ perl -E'use DateTime; say DateTime::TimeZone->VERSION;'
2.13

If I change "local" to "floating", I get symptoms similar to what you
report:

$ TZ=Asia/Manila perl -E'use DateTime; say
DateTime->now(time_zone=>"floating")->strftime("%Y-%m-%d %H:%M:%S %z
(%Z)");'
2017-10-31 17:57:03 +0000 (floating)

However, this is what "floating" is supposed to do, and it does the same
thing if TZ="America/Los_Angeles".

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