[PATCH v2 2/2] ntdll: sock_recv keeps message ordered

[Zebediah Figura]

On 12/6/21 19:30, Dongwan Kim wrote:
> Calling try_recv could make messages misordered.
> 
> Suppose that a server program calls a overlapped WSARecv
> and its operation is pending.
> Another program sends a message and wineserver is busy.
> The server program calls another overlapped WSARecv and
> it intercepts the message for the pending WSARecv.
> 
> The problem already had been discussed here
> https://www.winehq.org/pipermail/wine-devel/2021-May/186612.html
> 
> To avoid this situation, this kind of approach can be applied.
> 
> The server program needs to know if there are pending asyncs
> before calling try_recv.
> Wineserver notifies it whenever invoking APC_ASYNC_IO.
> Then, the server program updates it and check it before calling try_recv.

This is broken for a few reasons, but the main one is that socket 
handles are cross-process, which is the main reason that the server is 
involved in the first place.

As I asked the last time a patch like this was submitted [1], it would 
firstly be nice to know what application needs this, and second, it 
would be nice to have a test case (ideally in-tree, but if necessary 
out-of-tree) to validate that this guarantee holds.

[1] https://www.winehq.org/pipermail/wine-devel/2021-May/186848.html