On 2014-02-12 01:46 PM, Warner Losh wrote:
Other systems are less open, and sweep this data under the rug is also a valid
conclusion.
There's no mystery how Windows handles Leap Seconds - it doesn't.
Its off by the Leap Second until it re-syncs to NTP.
How the Windows Time service treats a leap second
http://support.microsoft.com/kb/909614
Its timezone information is dynamic, held in the Registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones
For example -
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
Zones\Eastern Standard Time
Display (UTC-05:00) Eastern Time (US & Canada)
Dlt Eastern Daylight Time
MUI_Display @tzres.dll,-110
MUI_Dlt @tzres.dll,-111
MUI_Std @tzres.dll,-112
Std Eastern Standard Time
TZI BINARY
And most entries include a "Dynamic DST" key -
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time
Zones\Eastern Standard Time\Dynamic DST
2006 BINARY
2007 BINARY
FirstEntry 2006
LastEntry 2007
These can be updated - (and probably are updated with a "Windows
Update", I've not verified that.)
August 2013 cumulative time zone update for Windows operating systems
http://support.microsoft.com/kb/2863058
And can be individually maintained -
How to configure the daylight saving time start date and end date for
Guatemala in Windows
http://support.microsoft.com/kb/918645
This policy of behavior makes Windows a little "safer" from Leap Seconds
and DST changes but its time is almost certainly wrong around changes
until it re-syncs.
-Brooks
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