HP-UX Reference (11i v1 05/09) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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ldterm(7) ldterm(7)

NAME

ldterm - standard STREAMS terminal line discipline module

SYNOPSIS

#include <sys/stream.h>

#include <sys/stropts.h>

#include <sys/termios.h>

#include <sys/bsdtty.h>

#include <sys/ttold.h>

#include <sys/strtio.h>

#include <sys/eucioctl.h>

int ioctl( fd, I_PUSH, "ldterm");

DESCRIPTION

ldterm is a STREAMS module that supplies the line discipline for streams-based terminal or pseudo-

terminal device drivers. This module provides most of the functions of the general terminal interface

described in termio (7). However, it does not perform the low-level device control functions speciﬁed by the

c_cflag word deﬁned by the POSIX termios structure or the System V termio structure (deﬁned

termios.h and termio.h, respectively). Also, some operations require the cooperation of the

modules and drivers pushed below the ldterm module in a tty or pty (slave) stream. This man page only

covers ldterm speciﬁc interface here and refers to the readers to termio(7) for the detail terminal inter-

face.

Internally, the ldterm module uses the Extended UNIX Code (EUC) character encoding scheme. This

encoding scheme enables the ldterm module to process multibyte characters as well as simple 8-bit char-

acters. It correctly handles backspacing, word erasing, and tab expansion for multibyte EUC characters.

The ldterm module provides standard terminal operation consistent with the behavior speciﬁed by

POSIX 1003.1 and System V Interface Deﬁnition (SVID) Third Edition. It also provides compatibility with

the behavior of the BSD 4.3 line discipline. Notice that on other STREAMS systems, the BSD 4.3 compati-

bility feature is usually provided by a separate STREAMS module called

ttcompat. Hence, applications

on HP-UX need not push ttcompat on top of ldterm to get BSD 4.3 compatibility. In fact, the

ttcompat module is not provided on the HP-UX system at all.

The ldterm module normally sits above either a STREAMS tty driver or a STREAMS pty slave driver.

The user issues an STREAMS I_PUSH ioctl(2) system call to push ldterm onto the stream once the

STREAMS tty or STREAMS pty slave device is opened.

STREAMS Messages

The ldterm module processes various types of STREAMS messages. The line discipline will act on any of

the following message types. Any others that the module receives, however, are passed onto the next

module on the stream.

Read-side Behavior

ldterm processes the following STREAMS messages on its input stream:

M_FLUSH

If FLUSHR is set, the read put routine ﬂushes the read queue, discards characters in the input

message buffers, and discards any partially buffered multibyte EUC characters. Then, it for-

wards the message upstream.

M_BREAK

The read put routine processes the message according to POSIX rules for processing BREAK

events, parity errors, and framing errors and signal generation (see termio(7) for detail). If

there is no data in the message, the message is assumed to represent an input BREAK event,

which is represented by a framing error with a character value of 0 (zero). If there is data in the

message, the data value is an integer that indicates the occurrence of an input BREAK event, or

a character received with a parity or framing error. The low-order 8 bits of the data value is the

byte that was read. If the TTY_PE ﬂag is set in the higher-order bits of this integer, then a

parity error was detected. If the TTY_FE ﬂag is set in the higher-order bits of this integer, a

framing error was detected.

After reading the data value, the read put routine discards the message.

HP-UX 11i Version 1: September 2005 − 1 − Hewlett-Packard Company Section 7−−59