Re: zip_file_set_mtime() bug?

[Thomas Klausner <tk%giga.or.at@localhost>]

On Wed, Nov 15, 2017 at 07:17:10PM +0100, Andreas Falkenhahn wrote:
> On 15.11.2017 at 18:39 Thomas Klausner wrote:
> 
> > On Wed, Nov 15, 2017 at 05:48:07PM +0100, Andreas Falkenhahn wrote:
> 
> >> I want to set the datestamp of a file inside a zip archive to
> >> 16-Sep-2017 08:34:56. This is my code:
> 
> >>       struct tm tm;
> 
> >>       tm.tm_sec = 56;
> >>       tm.tm_min = 34;
> >>       tm.tm_hour = 8;
> >>       tm.tm_mday = 16;
> >>       tm.tm_mon = 8;
> >>       tm.tm_year = 117;
> >>       tm.tm_isdst = -1;
> >>       
> >>       zip_file_set_mtime(arc, 0, mktime(&tm), 0);
> >>       
> >> When I compile and run this code on Linux, Ubuntu shows the
> >> file date correctly as 16-Sep-2017 08:34:56.
> 
> >> When I compile and run this code on Windows, however, Windows
> >> Explorer shows the file date as 16-Sep-2017 09:34:56, i.e.
> >> one hour later than what I passed to zip_file_set_mtime().
> 
> >> Is this a bug in libzip or am I doing something wrong here?
> 
> > libzip doesn't behave differently in this code path for the two
> > operating systems.
> 
> > I'd take a closer look at what you get from mktime() on the two
> > systems.
> 
> It's the same. So when I open the zip archive created on Ubuntu
> with Windows Explorer, Explorer also reports 09:34:56 whereas Ubuntu
> reports 08:34:56. Any idea what is the reason for that? Why
> does Windows Explorer add an hour?

I'm guessing that it thinks the time inside the zip archive is UTC,
and that you're in CET (= UTC+1), so it adds one hour when displaying
the time.
 Thomas