WSAOVERLAPPED

The WSAOVERLAPPED structure provides a communication medium between the initiation of an overlapped I/O operation and its subsequent completion. The WSAOVERLAPPED structure is designed to be compatible with the Win32 OVERLAPPED structure:

typedef struct _WSAOVERLAPPED { 

    DWORD        Internal;

    DWORD        InternalHigh;

    DWORD        Offset;

    DWORD        OffsetHigh;

    WSAEVENT     hEvent;

} WSAOVERLAPPED, LPWSAOVERLAPPED;

Members

Internal

This reserved field is used internally by the entity that implements overlapped I/O. For service providers that create sockets as installable file system (IFS) handles, this field is used by the underlying operating system. Other service providers (non-IFS providers) are free to use this field as necessary.

InternalHigh

Reserved field is used internally by the entity that implements overlapped I/O. For service providers that create sockets as IFS handles, this field is used by the underlying operating system. Non-IFS providers are free to use this field as necessary.

OffsetT

This field is reserved for service providers to use.

OffsetHigh

This field is reserved for service providers to use.

Event

If an overlapped I/O operation is issued without an I/O completion routine (lpCompletionRoutine is NULL), then this field should either contain a valid handle to a WSAEVENT object or be NULL. If lpCompletionRoutine is non-NULL then applications are free to use this field as necessary.