DosSetNmPHandState

This call sets the read and blocking modes of a named pipe.

Syntax

DosSetNmPHandState (Handle, PipeHandleState)

Parameters

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 behavior 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.

14-10 - 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.

Return Code

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

Remarks

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.

Example Code

C Binding

#define INCL_DOSNMPIPES

USHORT  rc = DosSetNmPHandState(Handle, PipeHandleState);

HPIPE            Handle;          /* Pipe handle */
USHORT           PipeHandleState; /* Pipe handle state */

USHORT           rc;              /* return code */

MASM Binding

EXTRN  DosSetNmPHandState:FAR
INCL_DOSNMPIPES     EQU 1

PUSH   WORD    Handle          ;Pipe handle
PUSH   WORD    PipeHandleState ;Pipe handle state
CALL   DosSetNmPHandState

Returns WORD