impl more overlapped by youknowone · Pull Request #6885 · RustPython/RustPython

Add comprehensive Windows async I/O support to the overlapped module:

Winsock Extensions:
- Initialize AcceptEx, ConnectEx, DisconnectEx, TransmitFile via WSAIoctl
- Proper cleanup with all four extension locks checked

Overlapped Methods:
- ReadFile, ReadFileInto: Async file reading
- WriteFile: Async file writing
- WSARecv, WSARecvInto: Async socket receive
- WSASend: Async socket send
- WSARecvFrom, WSARecvFromInto: Async UDP receive with address
- WSASendTo: Async UDP send to address
- AcceptEx: Async socket accept
- ConnectEx: Async socket connect
- DisconnectEx: Async socket disconnect
- TransmitFile: Async file transmission over socket
- ConnectNamedPipe, ConnectPipe: Named pipe support

Module Functions:
- CreateIoCompletionPort: IOCP creation/association
- GetQueuedCompletionStatus: Dequeue completion packets
- PostQueuedCompletionStatus: Post completion packets
- RegisterWaitWithQueue: Register wait with completion port callback
- UnregisterWait, UnregisterWaitEx: Unregister waits with proper cleanup
- BindLocal: Bind socket to local address
- CreateEvent, SetEvent, ResetEvent: Event object management
- FormatMessage: Windows error message formatting

Safety & Correctness:
- Validate buffer contiguity before async operations
- Validate size parameters to prevent buffer overflow
- Use Arc for RegisterWaitWithQueue callback data to prevent UAF
  (callback may run after UnregisterWait returns per Windows API docs)