DosQueryNPipeSemState returns information about the status of local named pipes that are attached to a shared event or multiple-wait (muxwait) semaphore. (Event semaphores are attached to local named pipes by calling DosSetNPipeSem.)

A record is returned for each local named pipe that is attached to the specified semaphore and whose state is either closed or allows blocking-mode input and output to be done. However, there is no guarantee that the records in the buffer refer only to named pipes that were opened by the process making this call. If the same semaphore has been attached to different named pipes by multiple processes, information about named pipes that are not accessible to the caller can be returned. For this reason, communicating processes should have a convention for key values to help identify the named pipes of interest. (A key value is specified when DosSetNPipeSem is called to attach the semaphore to a named pipe.)

If a process wants data in the buffer to refer only to its own named pipes, it must use a private event semaphore.