The Windows Sockets WSACleanup
function terminates use of the Windows Sockets DLL.
int WSACleanup (void);
An application or DLL is required to perform a successful WSAStartup
call before it can use Windows Sockets services. When it has completed the
use of Windows Sockets, the application or DLL must call WSACleanup
to deregister itself from a Windows Sockets implementation and allow the
implementation to free any resources allocated on behalf of the application or DLL.
Any pending blocking or asynchronous calls issued by any thread in this
process are canceled without posting any notification messages, or signaling any
event objects. Any pending overlapped send and receive operations (WSASend
with an overlapped socket) issued by any thread in this process are also
canceled without setting the event object or invoking the completion routine, if
specified. In this case, the pending overlapped operations fail with the error
status WSA_OPERATION_ABORTED. Any sockets open when WSACleanup
is called are reset and automatically deallocated as if closesocket
was called; sockets which have been closed with closesocket
but which still have pending data to be sent may be affected
the pending data may be lost if the Windows Sockets DLL is unloaded from
memory as the application exits. To insure that all pending data is sent an
application should use shutdown
to close the connection, then wait until the close completes before calling closesocket
. All resources and internal state, such as queued un-posted messages, must be
deallocated so as to be available to the next user.
There must be a call to WSACleanup
for every successful call to WSAStartup
made by a task. Only the final WSACleanup
for that task does the actual cleanup; the preceding calls simply decrement
an internal reference count in the Windows Sockets DLL.
The return value is zero if the operation was successful. Otherwise, the value
SOCKET_ERROR is returned, and a specific error number may be retrieved by
Attempting to call WSACleanup
from within a blocking hook and then failing to check the return code is a
common Windows Sockets programming error. If an application needs to quit while a
blocking call is outstanding, the application must first cancel the blocking
call with WSACancelBlockingCall
then issue the WSACleanup
call once control has been returned to the application.
In a multithreaded environment, WSACleanup
terminates Windows Sockets operations for all threads.
||A successful WSAStartup must occur before using this function.
||The network subsystem has failed.
||A blocking Windows Sockets 1.1 call is in progress, or the service provider is
still processing a callback function.
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