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)

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 in

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 interface.

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 compatibility

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 forwards 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.

M_DATA The read put routine processes the message according to the POSIX 1003.1 speciﬁcation,

using multibyte processing for backspacing, word erasing, and tab expansion as appropri-

ate.

HP-UX 11i Version 2: December 2007 Update − 1 − Hewlett-Packard Company 75