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Date: Mon, 26 Oct 2009 11:56:54 +0100
Reply-To: "Christian Franke" <Christian DOT Franke AT t-online DOT de>
To: "Cygwin" <cygwin AT cygwin DOT com>
Subject: Re: Time differences between USB - HD
From: "Christian Franke" <Christian DOT Franke AT t-online DOT de>
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Angelo Graziosi wrote
> Just now we are back to Standard Time, I noticed that the files on USB
> key have timestamps +1 hour, compared to the same on HD.
> 
> This happens only under Cygwin: there is not difference under DOS box.
> 

This is "normal" if the filesystems differ between HD (NTFS) and USB key
(FAT?). NTFS stores file times as UTC, FAT as local time.

The problem is the interesting design (IMO this is a bug:-) of the Win32
file time conversion functions:

http://msdn.microsoft.com/en-us/library/ms724277(VS.85).aspx
http://www.codeproject.com/KB/datetime/dstbugs.aspx
http://support.microsoft.com/kb/158588

The difference between Cygwin and other apps occur because Cygwin uses
its own (correct) UTC->localtime conversion but apps like explorer and
cmd uses the (broken) conversion from Win32 API.

Example: http://sourceware.org/ml/cygwin/2007-06/msg00455.html


Christian




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