tirdwr(7)                           CLIX                           tirdwr(7)



  NAME

    tirdwr - Read/write Transport Interface STREAMS module

  DESCRIPTION

    The tirdwr module is a STREAMS module that provides an alternate interface
    to a transport provider which supports the Transport Interface (TI)
    functions of the Network Services library.  (See section 3.)  This
    alternate interface allows a user to communicate with the transport
    protocol provider using the read() and write() functions.  The putmsg()
    and getmsg() functions may also be used.  However, putmsg() and getmsg()
    can only transfer data messages between user and stream.

    The tirdwr module must only be pushed (see I_PUSH in streamio) onto a
    stream terminated by a transport protocol provider which supports the TI.
    After the tirdwr module has been pushed onto a stream, none of the
    Transport Interface functions can be used.  Subsequent calls to TI
    functions will cause an error on the stream.  Once the error is detected,
    subsequent system calls on the stream will return an error with errno set
    to EPROTO.

    The following are the actions taken by the tirdwr module when pushed on
    the stream, popped (see I_POP in streamio) off the stream, or when data
    passes through it.

    push    When the module is pushed onto a stream, it will check any
            existing data destined for the user to ensure that only regular
            data messages are present.  It will ignore any messages on the
            stream that relate to process management, such as messages that
            generate signals to the user processes associated with the stream.
            If any other messages are present, the I_PUSH will return an error
            with errno set to EPROTO.

    write   The module will take the following actions on data that originated
            from a write() function:

            ⊕  All messages with the exception of messages that contain
               control portions (see the putmsg() and getmsg() functions) will
               be transparently passed onto the module's downstream neighbor.

            ⊕  Any zero-length data messages will be freed by the module and
               they will not be passed onto the module's downstream neighbor.

            ⊕  Any messages with control portions will generate an error, and
               any further system calls associated with the stream will fail
               with errno set to EPROTO.

    read    The module will take the following actions on data that originated
            from the transport protocol provider:




  2/94 - Intergraph Corporation                                              1

  tirdwr(7)                           CLIX                           tirdwr(7)



            ⊕  All messages with the exception of those that contain control
               portions (see the putmsg() and getmsg() functions) will be
               transparently passed onto the module's upstream neighbor.

            ⊕  The action taken on messages with control portions will be as
               follows:

               -- Messages that represent expedited data will generate an
                  error.  All further functions associated with the stream
                  will fail with errno set to EPROTO.

               -- Any data messages with control portions will have the
                  control portions removed from the message prior to passing
                  the message on to the upstream neighbor.

               -- Messages that represent an orderly release indication from
                  the transport provider will generate a zero-length data
                  message, indicating the end-of-file, which will be sent to
                  the reader of the stream.  The orderly release message
                  itself will be freed by the module.

               -- Messages that represent an abortive disconnect indication
                  from the transport provider will cause all further write()
                  and putmsg() functions to fail with errno set to ENXIO.  All
                  further read() and getmsg() functions will return zero-
                  length data (indicating end-of-file) once all previous data
                  has been read.

               -- With the exception of the above rules, all other messages
                  with control portions will generate an error and all further
                  functions associated with the stream will fail with errno
                  set to EPROTO.

            ⊕  Any zero-length data messages will be freed by the module and
               they will not be passed onto the module's upstream neighbor.

    pop     When the module is popped off the stream or the stream is closed,
            the module will take the following action:

            ⊕  If an orderly release indication has been previously received,
               an orderly release request will be sent to the remote side of
               the transport connection.

  ERRORS

    EPROTO   A message has been received or sent which is not supported by the
             Transport Interface.

    ENXIO    The transport provider has disconnected.

  RELATED INFORMATION



  2                                              Intergraph Corporation - 2/94

  tirdwr(7)                           CLIX                           tirdwr(7)



    Functions:  intro(2), getmsg(2), putmsg(2), read(2) write(2), intro(3)

    Files:  streamio(7), timod(7)

    AT&T UNIX System V STREAMS Programmer's Guide, AT&T UNIX System V Network
    Programmer's Guide
















































  2/94 - Intergraph Corporation                                              3