tirdwr(7)tirdwr(7)NAMEtirdwr - Transport Interface read/write interface STREAMS module
DESCRIPTIONtirdwr 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:
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tirdwr(7)tirdwr(7)
- 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 ALSOstreamio(7), timod(7)intro(2), getmsg(2), putmsg(2), read(2), write(2), intro(3)
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