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This function sets an application-defined procedure to be executed while waiting for the completion of a blocking call. A blocking call is any synchronous function that takes a long time to execute and does not return until complete. There are five blocking calls in this implementation of WinHLLAPI. The blocking calls are: Get Key (51), Wait (4), Pause (18), Send File (90), and Receive File (91).
FARPROC WinHLLAPISetBlockingHook(FARPROC lpfnBlockingHook)
This is a pointer to the new blocking procedure.
The WinHLLAPI implementation has a default blocking procedure that consists of nothing more than a message handler. This default mechanism is shown in the following example:
if (PeekMessage (&msg, NULL, 0, 0, xfPM_NOREMOVE))
if(msg.message = = WM_QUIT)
PeekMessage (&msg, NULL, 0, 0, PM_REMOVE);
The blocking hook is implemented on a per-thread basis. A blocking hook set by this function will stay in effect for the thread until it is replaced by another call to WinHLLAPISetBlockingHook() or until the default is restored by a call to WinHLLAPIUnhookBlockingHook().
The Blocking function must return FALSE if it receives a WM_QUIT message so WinHLLAPI can return control to the application to process the message and terminate gracefully. Otherwise, the function should return TRUE.
This function returns a pointer to the blocking function being replaced.