WSAGetOverlappedResult Function

The WSAGetOverlappedResult function retrieves the results of an overlapped operation on the specified socket.

Syntax

BOOL WSAAPI WSAGetOverlappedResult(
  __in   SOCKET s,
  __in   LPWSAOVERLAPPED lpOverlapped,
  __out  LPDWORD lpcbTransfer,
  __in   BOOL fWait,
  __out  LPDWORD lpdwFlags
);

Parameter

• s [in]
  A descriptor identifying the socket.

  This is the same socket that was specified when the overlapped operation was started by a call to any of the Winsock functions that supports overlappped operations. These functions include AcceptEx, ConnectEx, DisconnectEx, TransmitFile, TransmitPackets, WSARecv, WSARecvFrom, WSARecvMsg, WSASend, WSASendMsg, WSASendTo, and WSAIoctl.

• lpOverlapped [in]
  A pointer to a WSAOVERLAPPED structure that was specified when the overlapped operation was started. This parameter must not be a NULL pointer.

• lpcbTransfer [out]
  A pointer to a 32-bit variable that receives the number of bytes that were actually transferred by a send or receive operation, or by the WSAIoctl function. This parameter must not be a NULL pointer.

• fWait [in]
  A flag that specifies whether the function should wait for the pending overlapped operation to complete. If TRUE, the function does not return until the operation has been completed. If FALSE and the operation is still pending, the function returns FALSE and the WSAGetLastError function returns WSA_IO_INCOMPLETE. The fWait parameter may be set to TRUE only if the overlapped operation selected the event-based completion notification.

• lpdwFlags [out]
  A pointer to a 32-bit variable that will receive one or more flags that supplement the completion status. If the overlapped operation was initiated through WSARecv or WSARecvFrom, this parameter will contain the results value for lpFlags parameter. This parameter must not be a NULL pointer.

Rückgabewert

If WSAGetOverlappedResult succeeds, the return value is TRUE. This means that the overlapped operation has completed successfully and that the value pointed to by lpcbTransfer has been updated.

If WSAGetOverlappedResult returns FALSE, this means that either the overlapped operation has not completed, the overlapped operation completed but with errors, or the overlapped operation's completion status could not be determined due to errors in one or more parameters to WSAGetOverlappedResult. On failure, the value pointed to by lpcbTransfer will not be updated. Use WSAGetLastError to determine the cause of the failure (either by the WSAGetOverlappedResult function or by the associated overlapped operation).

Hinweise

The WSAGetOverlappedResult function reports the results of the overlapped operation specified in the lpOverlapped parameter for the socket specified in the s parameter. The WSAGetOverlappedResult function is passed the socket descriptor and the WSAOVERLAPPED structure that was specified when the overlapped function was called. A pending operation is indicated when the function that started the operation returns FALSE and the WSAGetLastError function returns WSA_IO_PENDING. When an I/O operation such as WSARecv is pending, the function that started the operation resets the hEvent member of the WSAOVERLAPPED structure to the nonsignaled state. Then, when the pending operation has completed, the system sets the event object to the signaled state.

If the fWait parameter is TRUE, WSAGetOverlappedResult determines whether the pending operation has been completed by waiting for the event object to be in the signaled state. A client may set the fWait parameter to TRUE, but only if it selected event-based completion notification when the I/O operation was requested. If another form of notification was selected, the usage of the hEvent parameter of the WSAOVERLAPPED structure is different, and setting fWait to TRUE causes unpredictable results.

If the WSAGetOverlappedResult function is called with the lpOverlapped, lpcbTransfer, or lpdwFlags parameter set to a NULL pointer on Windows Vista, this will result in an access violation. If the WSAGetOverlappedResult function is called with the lpOverlapped, lpcbTransfer, or lpdwFlags parameter set to a NULL pointer on Windows Server 2003 and earlier, this will result in the WSAEFAULT error code being returned.

Hinweis   All I/O is canceled when a thread exits. For overlapped sockets, pending asynchronous operations can fail if the thread is closed before the operations complete. See ExitThread for more information.

Anforderungen

Siehe auch

Winsock Reference

Winsock Functions

WSAAccept

WSAConnect

WSACreateEvent

WSAIoctl

WSARecv

WSARecvFrom

WSASend

WSASendTo

WSAWaitForMultipleEvents