tirdwr(7M) STREAMS Modules 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 sup‐
ports 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
existing data destined for the user to ensure that only
regular data messages are present. It ignores any mes‐
sages on the stream that relate to process management,
such as messages that generate signals to the user pro‐
cesses associated with the stream. If any other mes‐
sages 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:
· 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.
· Any zero length data messages are freed by the
module and they will not be passed onto the mod‐
ule's downstream neighbor.
· 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 transparently passed onto the module's
upstream neighbor. The action taken on messages with
control portions will be as follows:
· Any data messages with control portions have the
control portions removed from the message before
to passing the message on to the upstream neigh‐
bor.
· 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
module.
· 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.
· 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:
· 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
SunOS 5.10 3 Jul 1990 tirdwr(7M)
