TIRDWR(7M)TIRDWR(7M)NAMEtirdwr - Transport Interface read/write interface STREAMS module
SYNOPSIS
int ioctl( fd, I_PUSH, "tirdwr");
DESCRIPTIONtirdwr is a STREAMS module that provides an alternate interface to a
transport provider which supports the Transport Interface ("TI") func‐
tions 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; con‐
trol portions are disallowed.
The tirdwr module must only be pushed (see I_PUSH in streamio(7I)) 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
TI functions can be used. Subsequent calls to TI functions cause an
error on the stream. Once the error is detected, subsequent system
calls on the stream 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(7I)) off the stream, or
when data passes through it.
push
When the module is pushed onto a stream, it checks any exist‐
ing data destined for the user to ensure that only regular
data messages are present. It ignores 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 takes the following actions on data that originated
from a write system call:
o All messages with the exception of messages that
contain control portions (see the putmsg and getmsg
system calls) are transparently passed onto the
module's downstream neighbor.
o Any zero length data messages are freed by the mod‐
ule and they will not be passed onto the module's
downstream neighbor.
o Any messages with control portions generate an
error, and any further system calls associated with
the stream fails with errno set to EPROTO.
read
The module takes 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) are trans‐
parently passed onto the module's upstream neighbor. The
action taken on messages with control portions will be as fol‐
lows:
o Any data messages with control portions have the
control portions removed from the message before to
passing the message on to the upstream neighbor.
o Messages that represent an orderly release indica‐
tion from the transport provider 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 is freed by the mod‐
ule.
o Messages that represent an abortive disconnect
indication from the transport provider cause all
further write and putmsg system calls to fail with
errno set to ENXIO. All further read and getmsg
system calls return zero length data (indicating
end of file) once all previous data has been read.
o With the exception of the above rules, all other
messages with control portions generate an error
and all further system calls associated with the
stream will fail with errno set to EPROTO.
Any zero length data messages are freed by the module and they
are not passed onto the module's upstream neighbor.
pop
When the module is popped off the stream or the stream is
closed, the module takes the following action:
o If an orderly release indication has been previ‐
ously received, then an orderly release request
will be sent to the remote side of the transport
connection.
SEE ALSOIntro(3), getmsg(2), putmsg(2), read(2), write(2), Intro(3),
streamio(7I), timod(7M)
STREAMS Programming Guide
Jul 3, 1990 TIRDWR(7M)
