This call sets the read and blocking modes of a named pipe.
DosSetNmPHandState (Handle, PipeHandleState)
- Handle (HPIPE) - input
- Handle of the named pipe returned by DosMakeNmPipe or DosOpen.
- PipeHandleState (USHORT) - input
- Named pipe handle state, consists of the following bit fields:
- 15 - Blocking flag:
- 0 = Reads /Writes block if no data available.
- 1 = Reads/Writes return immediately if no data available.
- Reads normally block until at least partial data can be returned. Writes by default block until all bytes requested have been written.
- Non-blocking mode (B = 1) changes this behaviour as follows:
- DosRead - Returns BytesRead = 0 if no data is available.
- DosWrite - Returns BytesWritten = 0 if there is not enough buffer space available in the pipe. Otherwise, the entire data area is transferred.
- 14 - Reserved and must be set to zero.
- 13-11 - timer (values approximate from 0 to 14 seconds in 2 second increments)
- 10 - Reserved and must be set to zero.
- 9-8 - Read Mode flag:
- 00 = Read pipe as byte stream.
- 01 = Read pipe as a message stream.
- 7-0 - Reserved and must be set to zero.
- rc (USHORT) - return
- Return code descriptions are:
- 0 NO_ERROR
- 87 ERROR_INVALID_PARAMETER
- 230 ERROR_BAD_PIPE
- 231 ERROR_PIPE_BUSY
- 233 ERROR_PIPE_NOT_CONNECTED
The read mode and blocking/non-blocking mode of a named pipe can be changed. The pipe mode can not be changed to non-blocking when another thread is blocked on an I/O to the same end of the pipe.
#define INCL_DOSNMPIPES USHORT rc = DosSetNmPHandState(Handle, PipeHandleState); HPIPE Handle; /* Pipe handle */ USHORT PipeHandleState; /* Pipe handle state */ USHORT rc; /* return code */
EXTRN DosSetNmPHandState:FAR INCL_DOSNMPIPES EQU 1 PUSH WORD Handle ;Pipe handle PUSH WORD PipeHandleState ;Pipe handle state CALL DosSetNmPHandState Returns WORD