ReadFile and WriteFile in overlapped mode

[Tony Bryant]

On Fri, 05 Apr 2002 06:01, Jacques Gelinas wrote:
> I have been looking at those two functions and some specs. My understanding
> is that those function do not work at all in overlapped (async mode).
> Currently (latest stuff in CVS), both function handle overlap mode like
> this
>
> a)	Give it a try in synchronous mode using a combination
> 	of pread/read and pwrite/write.
>
> b)	If not enough bytes were read or written, a request
> 	is sent to wineserver to perform and asynchronous
> 	operation. This request always fail. (don't know why yet).
>
> There is two problem here. If step a succeed, no event will ever be
> generated since step be is not performed. Application doing the following
> sequence
>
> 	ReadFile
> 	..
> 	WaitOnSingleObject
>
> will wait forever. Some borland Builder classes do this
>
> My understanding is that step a should never be done and only step b.
> Is that correct ?
>
> Now, why step b is failing is another story.
>


I fixed this a while ago, but never finished submitting the patch. The
problem is that wine uses async callbacks to signal the event in the 
overlapped structure, which is a problem, because async callbacks can only
happen when WaitOnSingleObjectEx specifically allows them. The solution is to
have the wine directly trigger the event without going through the async
callback system.