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

[Piotr Caban]

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 
---
  dlls/msvcrt/time.c | 5 ++---
  1 file changed, 2 insertions(+), 3 deletions(-)

[Zebediah Figura]

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
>
> 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?

[Piotr Caban]

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
> >
> > 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.

Thanks,
Piotr

[Zebediah Figura (she/her)]

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
> > >
> > > 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

[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
> > > >
> > > > 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.