DosSetNmPHandState

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:

Bit

Description
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.
rc (USHORT) - return
Return code descriptions are:
• 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.

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