[PATCH v2] msvcrt: Don't use GetDaylightFlag function in _ftime64.

[Piotr Caban]

On 11/1/21 6:15 PM, Zebediah Figura (she/her) wrote:
> On 11/1/21 11:58, Piotr Caban wrote:
>> On 11/1/21 5:37 PM, Zebediah Figura wrote:
>>> On 11/1/21 9:07 AM, Piotr Caban wrote:
>>>>
>>>> The function is not available on current Windows releases.
>>>>
>>>> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=51959
>>>> Signed-off-by: Piotr Caban <piotr at codeweavers.com>
>>>> ---
>>>>    dlls/msvcrt/time.c | 5 ++---
>>>>    1 file changed, 2 insertions(+), 3 deletions(-)
>>>>
>>>>
>>>
>>> This was added in the first place to avoid the overhead of loading 
>>> tzres.dll. Is that no longer a concern?
>>>
>> It's just copying body of GetDaylightFlag function to msvcrt. There's 
>> no change regarding tzres.dll being loaded.
>>
>> If GetTimeZoneInformation performance is a concern we should probably 
>> avoid calling it too often.
> 
> Hrm, that's true. I distinctly remember 2efc73b96811 being an 
> alternative to caching the time zone information (cf [1]), but on 
> examination it was a no-op even then...
> 
> [1] https://www.winehq.org/pipermail/wine-devel/2018-December/137085.html

We're currently caching time zone name in GetDynamicTimeZone 
information, so it should no longer be a problem. GetDaylightFlag was 
using RtlQueryTimeZoneInformation to avoid localized time zone name lookup.