tirdwr(7)

NAME
     tirdwr - Transport Interface read/write interface STREAMS module

DESCRIPTION
     tirdwr 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 3N).  This alternate
     interface allows a user to communicate with the transport protocol
     provider using the read(2) and write(2) system calls.  The putmsg(2) and
     getmsg(2) system calls 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(7)] 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(7)] 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 system call:

               -  All messages with the exception of messages that contain
                  control portions (see the putmsg and getmsg system calls)
                  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:
               -  All messages with the exception of those that contain
                  control portions (see the putmsg and getmsg system calls)
                  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 system calls 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 system calls to fail with
                       errno set to ENXIO.  All further read and getmsg system
                       calls 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 system calls 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, then an orderly release request will be sent to
                  the remote side of the transport connection.

SEE ALSO
     streamio(7), timod(7)
     intro(2), getmsg(2), putmsg(2), read(2), write(2), intro(3)