Overlapped I/O + hEvent == NULL reopened + other questions

[Thomas Charbonnel]

Hi,

I'm trying to migrate a proprietary TCP/IP client/server db application
from Windows NT to Linux using Wine, and am encountering some
difficulties.

* First of all the application uses overlapped I/O in an unconventionnal
way. The application scenario is as follows : Setup server socket
Call WSAAsyncSelect
On accept, create a new window associated with the new socket
Call WSAAsyncSelect for this new socket/window.
On network event on the new socket, if the FD_READ event is passed to
the WindowProc, call ReadFile with an overlapped struct, but hEvent ==
NULL On IO_PENDING_READ_ERROR, call GetOverlappedResult with bWait set
to TRUE
There was a thread about this on this list on November 2002 ("Overlapped
I/O without an hEvent"). At that time Martin Wilck submited a patch that
did not get commited to CVS. I got things working by slightly modifying
his patch. The idea was floating around in the November thread : in the
GetOverlappedResult function, if the bWait flag is set, then wait
calling WaitForSingleObjectEx with the socket handle passed in instead
of the overlapped structure handle. I suspect this method is unclean,
but works for me as the server app I'm trying to run instantiates a
window (thus a WindowProc) per client. I'm waiting for your comments and
suggestions on how to properly handle this.

* Next I have a problem with high network loads (maybe related to the
previous issue). When I run the sever app in Wine and access it with a
remote client, operations generating a high network load tend to be
unstable. Most of the time the client application hangs at some point, and
sometimes the server hangs too. This does not happen if I run the client
with Wine on the same machine as the server. Are they known issues with
the winsock implementation ?

* Wine used to crash because the server app called
WritePrivateProfileString with a NULL lpFileName. I fixed this by
returning FALSE if lpFileName == NULL, but I don't know how windows
handles this. The app calls WritePrivateProfileString with a proper file
name a couple of times before setting it to NULL, so I suspect windows is
caching the file name.

* The client comes with a printing helper app. They communicate through
dde. I get the 'fixme:class:get_class_ptr reading from class of other
process window' message. How is this supposed to be handled ?

* Minor remaining problems :
- the end of tooltip texts is garbled
- help doesn't work (it seems the help file name is not passed as a
parameter)

Thanks for your attention,
Thomas

[Mike Hearn]

> * Next I have a problem with high network loads (maybe related to the
> previous issue). When I run the sever app in Wine and access it with a
> remote client, operations generating a high network load tend to be
> unstable. Most of the time the client application hangs at some point, and
> sometimes the server hangs too. This does not happen if I run the client
> with Wine on the same machine as the server. Are they known issues with
> the winsock implementation ?

Not sure, but I don't think Wine is used for server programs very often
so it's quite possible parts will crack under high loading.
> * Wine used to crash because the server app called
> WritePrivateProfileString with a NULL lpFileName. I fixed this by
> returning FALSE if lpFileName == NULL, but I don't know how windows
> handles this. The app calls WritePrivateProfileString with a proper file
> name a couple of times before setting it to NULL, so I suspect windows is
> caching the file name.

Well, most functions just return a fail code in this case I think, but
if you're not sure you can write a little test case on Windows to find
out. Feel free to submit this patch btw.
> * The client comes with a printing helper app. They communicate through
> dde. I get the 'fixme:class:get_class_ptr reading from class of other
> process window' message. How is this supposed to be handled ?

This is because Wine doesn't implement remote process window stuff/ipc
yet, Alexandre is working on this. I don't think DDE should need it
though.
> * Minor remaining problems :
> - the end of tooltip texts is garbled
> - help doesn't work (it seems the help file name is not passed as a
> parameter)
>
> Thanks for your attention,
> Thomas

-- 
Mike Hearn <m.hearn(a)signal.qinetiq.com>
QinetiQ - Malvern Technology Center

[Sylvain Petreolle]

Depends on what windows version you emulate :/.
See
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/bas...
> * Wine used to crash because the server app called
> WritePrivateProfileString with a NULL lpFileName. I fixed this by
> returning FALSE if lpFileName == NULL, but I don't know how windows
> handles this. The app calls WritePrivateProfileString with a proper
> file
> name a couple of times before setting it to NULL, so I suspect
> windows is
> caching the file name.

=====
Sylvain Petreolle (spetreolle at users dot sourceforge dot net) ICQ #170597259
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