HP-UX Reference (11i v2 07/12) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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ldterm(7) ldterm(7)

Write-side Behavior

ldterm processes the following STREAMS messages on its output stream. Messages not listed here are

simply forwarded downstream.

M_FLUSH The write put routine ﬂushes the write queue and discards any buffered output data. Then,

it forwards the message downstream.

M_DATA The write service routine processes the data according to the POSIX 1003.1 speciﬁcation

output ﬂags. It sends the processed characters downstream to the driver when the output

queue ﬁlls up and all of the data is processed.

M_IOCTL The write put routine validates the format of the

M_IOCTL message and checks for known

commands. If the message format is invalid, it turns the

M_IOCTL message into an

M_IOCNAK message, and returns the message upstream. If the I/O control command is

not recognized, it forwards the M_IOCTL message downstream for processing by other

modules.

The write put routine determines if the command is one that must be processed in the

proper sequence relative to M_DATA messages. If so, it queues the

M_IOCTL message to

the write queue for later processing by the write service routine. Commands that require

processing in sequence are:

TCSETSW, TCSETSF, TCSETAW, TCSETAF, TCSBRK

Otherwise, the module’s write put routine processes the command immediately. Detailed

descriptions of the preceding

ioctl commands are provided in the ioctlCommands subsec-

tion, below.

M_READ This message is sent by the stream head to notify downstream modules when an applica-

tion has issued a read request and there is not enough data queued at the stream head to

satisfy the request. The M_READ is sent downstream normally when ldterm is operating

in non-canonical input mode. If

VTIME is positive, the write put routine starts an input

timer. When the timer expires, it sends all buffered input upstream. Then, it forwards the

M_READ message downstream.

ioctl Commands

The ldterm module acts on two categories of ioctl commands:

• Primary terminal I/O control commands

• BSD 4.3 compatibility terminal I/O control commands

Detail descriptions on how to use these

ioctls can be found on the termio(7) man page. NOTE: the

FIO[xyz] ioctls documented on termio(7) are currently not supported on ldterm.

Primary Terminal I/O Control Commands

The ldterm module acts on the following primary terminal I/O commands:

TCSETS, TCSETSW, TCSETSF

When the ldterm module receives any of these commands in an M_IOCTL message, it

forwards them downstream. When it receives the M_IOCACK message in the read queue,

it copies the POSIX termios information from the message into the internal POSIX

termios structure and forwards the message upstream. If a mode change requires

options at the stream head to be changed, an M_SETOPTS message is sent upstream. If

the ICANON ﬂag is turned on or off, the read mode at the stream head is changed to

message-nondiscard (RMSGN) with read notiﬁcation on (SO_MREADON )orbyte-stream

mode (

RNORM) with read notiﬁcation off (SO_MREADOFF ), respectively. If the TOSTOP

ﬂag is turned on or off, the tostop mode at the stream head is turned on (SO_TOSTOP )or

off (SO_TONSTOP ), respectively.

TCGETS The ldterm module forwards the M_IOCTL message downstream. When it receives the

M_IOCACK message in the read queue, it copies the CLOCAL ﬂags and speeds from the

message into the internal POSIX termios structure. Then, it copies the entire structure

into the M_IOCACK message and forwards the message upstream.

TCSETA, TCSETAW, TCSETAF

These commands set the old System V termio information. The ldterm module con-

verts the message to a POSIX termios M_IOCTL message, then forwards the message

with a corresponding POSIX termios command (i.e. TCSETS, TCSETSW, TCSETSF).

HP-UX 11i Version 2: December 2007 Update − 3 − Hewlett-Packard Company 77