Re: msvcrt: Make the first call to fwrite bufferred (try2)

[Andreas Fuchs]

Hi Piotr, Hi all,

I traced down this commit as the origin of the regression, where I cannot parse stdout of wine correctly anymore.
See also https://bugs.winehq.org/show_bug.cgi?id=37345

I hope, sombody knowledgable (Piotr maybe you as the author) could help me figure this out or even provide a fix...

Description:
When calling wine from another process after redirecting stdout to a pipe, wine does not flush the stdout-buffer correctly anymore (Wine 1.6 did correctly).

Attached is a usecase. To test do:
i686-w64-mingw32-gcc helloworld.c
gcc callwine.c
./a.out

What will happen is:
- on a buggy wine it will take 10 seconds and then all of the stdout-buffer is flushed on the exit of the child. (imagine the child would run longer than the 10 seconds)
- on a good wine we will see some stdout-content then 10 second sleep and then the rest of the content.

This is a regression that happened between 1.7.4 and 1.7.5. The bisect identified commit afec0b00bd6250fe21e8deccbc8116a4aca6a7a4 "msvcrt: Make the first call to fwrite buffered." as problem.

The attached patch is a revert of this commit ported forward to 1.7.27. Unfortunately I don't quite grasp the logics of the offending commit. If somebody who knows that patch could help, I'd highly appreciate it.

Cheers,
Andreas

msvcrt: Make the first call to fwrite bufferred (try2)

[Piotr Caban]

Hi,

On 10/02/14 10:28, Andreas Fuchs wrote:
> Hi Piotr, Hi all,
>
> I traced down this commit as the origin of the regression, where I cannot parse stdout of wine correctly anymore.
> See also https://bugs.winehq.org/show_bug.cgi?id=37345
>
> I hope, sombody knowledgable (Piotr maybe you as the author) could help me figure this out or even provide a fix...
>
> Description:
> When calling wine from another process after redirecting stdout to a pipe, wine does not flush the stdout-buffer correctly anymore (Wine 1.6 did correctly).
>
> Attached is a usecase. To test do:
> i686-w64-mingw32-gcc helloworld.c
> gcc callwine.c
> ./a.out
>
> What will happen is:
> - on a buggy wine it will take 10 seconds and then all of the stdout-buffer is flushed on the exit of the child. (imagine the child would run longer than the 10 seconds)
> - on a good wine we will see some stdout-content then 10 second sleep and then the rest of the content.
> this is not a bug. The pipes are supposed to be buffered on windows.

The simple way of reproducing it is following:
i686-w64-mingw32-gcc helloworld.c
wine a.exe |more (linux)
a.exe |more (windows)
In both cases you will see all of the output after 10 seconds.

Cheers,
Piotr

msvcrt: Make the first call to fwrite bufferred (try2)

[Andreas Fuchs]

Hi Piotr,

thanks for clearing this up for me...
I was caught so off guard by the change in behavior that it did not
occur to me that this was actually a correction...

Sorry for the trouble...

Cheers,
Andreas

Am Donnerstag, den 02.10.2014, 11:01 +0200 schrieb Piotr Caban:
> Hi,
>
> On 10/02/14 10:28, Andreas Fuchs wrote:
> > Hi Piotr, Hi all,
> >
> > I traced down this commit as the origin of the regression, where I cannot parse stdout of wine correctly anymore.
> > See also https://bugs.winehq.org/show_bug.cgi?id=37345
> >
> > I hope, sombody knowledgable (Piotr maybe you as the author) could help me figure this out or even provide a fix...
> >
> > Description:
> > When calling wine from another process after redirecting stdout to a pipe, wine does not flush the stdout-buffer correctly anymore (Wine 1.6 did correctly).
> >
> > Attached is a usecase. To test do:
> > i686-w64-mingw32-gcc helloworld.c
> > gcc callwine.c
> > ./a.out
> >
> > What will happen is:
> > - on a buggy wine it will take 10 seconds and then all of the stdout-buffer is flushed on the exit of the child. (imagine the child would run longer than the 10 seconds)
> > - on a good wine we will see some stdout-content then 10 second sleep and then the rest of the content.
> > this is not a bug. The pipes are supposed to be buffered on windows.
>
> The simple way of reproducing it is following:
> i686-w64-mingw32-gcc helloworld.c
> wine a.exe |more (linux)
> a.exe |more (windows)
> In both cases you will see all of the output after 10 seconds.
>
> Cheers,
> Piotr