receive_all
Description:
Receive the entire data stream, sending the data to the requested data sink.
This is simply a convenient alternative to virStreamRecv, for apps that do blocking-I/o.
Parameters:
| this | the stream | 
| cancellable | cancellation notifier | 
| func | the callback for writing data to application | 
| user_data | data to be passed to  | 
Returns:
| the number of bytes consumed or -1 upon error |