[Bug 10176] rFactor Dedicated not working anymore after update

[wine-bugs at winehq.org]

http://bugs.winehq.org/show_bug.cgi?id=10176

Ken Richardson <ktrichardson at eastlink.ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ktrichardson at eastlink.ca

--- Comment #34 from Ken Richardson <ktrichardson at eastlink.ca> 2010-10-16 16:03:39 CDT ---
I have spent significant time troubleshooting this issue and found the cause
and solution. I have tested with ARCA Sim Racing and rFactor. Both these
applications use common code and therefore have the same issue. 

The problem is how Wine handles the Winsock2 "Select" function. When a call is
made to Select and you pass read, write, and exception fd_set structures with
all three fd_count values set to 0, Windows will return error code WSAEINVAL
but Wine returns 0 (no error). The rFactor and ASR code is written to handle
the WSAEINVAL return value by re-initializing the fd_set structures and looping
to call select again. Because Wine does not return this error for this
condition the structures do not get re-initialized.

You are probably asking how the structures get changed? rFactor and ASR both
initialize the fd_set structure fd_count value to 1 and provide one socket
handle in the fd_array member for the read and exception parameters. The write
parameter fd_count is set to 0, not used. This is done in the listening thread
initialization code. The Winsock2 "Select" function modifies the fd_count
values by decrementing them to 0. This behavior is true for Windows and Wine.
The difference, and cause of this bug, is Wine does not return WSAEINVAL if you
pass 0 for all fd_count values.

I fixed the problem by "hacking" the NetCommUtilPlugin.dll rFactor and ASR file
to re-initialize the fd_set structures and now it works perfectly under Wine. I
have also passed this on to ISI who will likely not care about supporting Wine.


Here's the rFactor code, see my comments:

.text:1000CCD3 loc_1000CCD3:                           ; CODE XREF:
sub_1000CC60+198j
.text:1000CCD3                 lea     ecx, [esp+6A4h+timeout] ; <-- Start of
loop, push fd_set structure pointers to stack and make Select call.
.text:1000CCD7                 push    ecx             ; timeout
.text:1000CCD8                 lea     edx, [esp+6A8h+timeout.fd_array+14h]
.text:1000CCDC                 push    edx             ; exceptfds
.text:1000CCDD                 lea     eax, [esp+6ACh+writefds]
.text:1000CCE4                 push    eax             ; writefds
.text:1000CCE5                 lea     ecx, [esp+6B0h+buf]
.text:1000CCEC                 push    ecx             ; readfds
.text:1000CCED                 push    0               ; nfds
.text:1000CCEF                 mov     [esp+6B8h+var_698], 10h
.text:1000CCF7                 call    ds:select
.text:1000CCFD                 test    eax, eax
.text:1000CCFF                 jz      loc_1000CDF1    ; <-- Return 0, nothing
ready to read and no exception. Wine always takes this jump.
.text:1000CD05                 mov     eax, s
.text:1000CD0A                 lea     edx, [esp+6B8h+timeout.fd_array]
.text:1000CD0E                 push    edx             ; fd_set *
.text:1000CD0F                 push    eax             ; SOCKET
.text:1000CD10                 call    __WSAFDIsSet
.text:1000CD15                 test    eax, eax
.text:1000CD17                 jnz     loc_1000CDF1    ; <-- Timeout, jump to
end of loop.
.text:1000CD1D                 mov     edx, s
.text:1000CD23                 lea     ecx, [esp+6C0h+timeout.fd_array+0FCh]
.text:1000CD2A                 push    ecx             ; fd_set *
.text:1000CD2B                 push    edx             ; SOCKET
.text:1000CD2C                 call    __WSAFDIsSet
.text:1000CD31                 test    eax, eax
.text:1000CD33                 jz      loc_1000CDD6    ; <-- WSAEINVAL error,
jump to re-initialization code, then end of loop
.text:1000CD39                 lea     eax, [esp+6C8h+to.sa_data+0Ah]
.text:1000CD3D                 push    eax             ; fromlen
.text:1000CD3E                 mov     eax, s

Hope this helps.
Ken

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