WSAGetOverlappedResult (Compact 2013)

3/26/2014

This function returns the results of an overlapped operation on the specified socket.

Syntax

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

Parameters

• s
  [in] Descriptor identifying the socket. This is the same socket that was specified when the overlapped operation was started by a call to the WSARecv, WSARecvFrom, WSASend, WSASendTo, or WSAIoctl function.

• lpOverlapped
  [in] Pointer to a WSAOVERLAPPED structure that was specified when the overlapped operation was started.

• lpcbTransfer
  [out] Pointer to a 32-bit variable that receives the number of bytes that were actually transferred by a send or receive operation or by WSAIoctl.

• fWait
  [in] 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] 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 value for the lpFlags parameter.

Return Value

If no error occurs, this function returns TRUE. This means that the overlapped operation has completed successfully and that the value pointed to by lpcbTransfer has been updated. If this function 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 of WSAGetOverlappedResult or of the associated overlapped operation).

The following table shows a list of possible error codes.

Error code	Description
WSANOTINITIALISED	A successful WSAStartup call must occur before using this function.
WSAENETDOWN	The network subsystem has failed.
WSAENOTSOCK	The descriptor is not a socket.
WSA_INVALID_HANDLE	The hEvent parameter of the WSAOVERLAPPED structure does not contain a valid event object handle.
WSA_INVALID_PARAMETER	One of the parameters is unacceptable.
WSA_IO_INCOMPLETE	The fWait parameter is FALSE and the I/O operation has not yet completed.
WSAEFAULT	One or more of the lpOverlapped, lpcbTransfer, or lpdwFlags arguments are not a valid part of the user address space.

Remarks

This function reports the results of the last overlapped operation for the specified socket. This 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 WSAGetLastError returns WSA_IO_PENDING. When an I/O operation such as the WSARecv function 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.

With the exception of SIO_ROUTING_INTERFACE_CHANGE and SIO_ADDRESS_LIST_CHANGE, all network drivers running in the kernel and calling into Winsock APIs cannot use overlapped I/O. For more information, see WSARecv, WSARecvFrom, WSASend, WSASendTo, and WSAIoctl.

Requirements

Header	winsock2.h
Library	Ws2.lib

See Also

Reference

Windows-Specific Extension Functions
WSARecv
WSARecvFrom
WSASend
WSASendTo
WSAIoctl