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Copyright (c) 2001, Sun Microsystems, Inc. All Rights Reserved.
Copyright 2001 AT&T
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ttcompat - V7, 4BSD and XENIX STREAMS compatibility module

#define BSD_COMP
#include <sys/stropts.h>
#include <sys/ioctl.h>
ioctl(fd, I_PUSH, "ttcompat");

ttcompat is a STREAMS module that translates the ioctl calls supported by the older Version 7, 4BSD, and XENIX terminal drivers into the ioctl calls supported by the termio interface (see termio(4I)). All other messages pass through this module unchanged; the behavior of read and write calls is unchanged, as is the behavior of ioctl calls other than the ones supported by ttcompat.

This module can be automatically pushed onto a stream using the autopush mechanism when a terminal device is opened; it does not have to be explicitly pushed onto a stream. This module requires that the termios interface be supported by the modules and the application can push the driver downstream. The TCGETS, TCSETS, and TCSETSF ioctl calls must be supported. If any information set or fetched by those ioctl calls is not supported by the modules and driver downstream, some of the V7/4BSD/XENIX functions may not be supported. For example, if the CBAUD bits in the c_cflag field are not supported, the functions provided by the sg_ispeed and sg_ospeed fields of the sgttyb structure (see below) will not be supported. If the TCFLSH ioctl is not supported, the function provided by the TIOCFLUSH ioctl will not be supported. If the TCXONC ioctl is not supported, the functions provided by the TIOCSTOP and TIOCSTART ioctl calls will not be supported. If the TIOCMBIS and TIOCMBIC ioctl calls are not supported, the functions provided by the TIOCSDTR and TIOCCDTR ioctl calls will not be supported.

The basic ioctl calls use the sgttyb structure defined by <sys/ttold.h> (included by <sys/ioctl.h>):

struct sgttyb {
 char sg_ispeed;
 char sg_ospeed;
 char sg_erase;
 char sg_kill;
 int sg_flags;
};

The sg_ispeed and sg_ospeed fields describe the input and output speeds of the device. If the speed set on the device is over B38400, then it is reported as B38400 for compatibility reasons. If it is set to B38400 and the current speed is over B38400, the change is ignored. See TIOCGETP and TIOCSETP below. The sg_erase and sg_kill fields of the argument structure specify the erase and kill characters respectively, and reflect the values in the VERASE and VKILL members of the c_cc field of the termios structure.

The sg_flags field of the argument structure contains several flags that determine the system's treatment of the terminal. They are mapped into flags in fields of the terminal state, represented by the termios structure.

Delay type 0 (NL0, TAB0, CR0, FF0, BS0) is always mapped into the equivalent delay type 0 in the c_oflag field of the termios structure. Other delay mappings are performed as follows:

sg_flags c_oflag

BS1 BS1

FF1 VT1

CR1 CR2

CR2 CR3

CR3 CR0 (not supported)

TAB1 TAB1

TAB2 TAB2

XTABS TAB3

NL1 ONLRET|CR1

NL2 NL1

NL3 NL0 (not supported)

If previous TIOCLSET or TIOCLBIS ioctl calls have not selected LITOUT or PASS8 mode, and if RAW mode is not selected, the ISTRIP flag is set in the c_iflag field of the termios structure, and the EVENP and ODDP flags control the parity of characters sent to the terminal and accepted from the terminal, as follows: 0 (neither EVENP nor ODDP)

EVENP ODDP EVENP|ODDP or ANYP

The RAW flag disables all output processing (the OPOST flag in the c_oflag field, and the XCASE and IEXTEN flags in the c_iflag field are cleared in the termios structure) and input processing (all flags in the c_iflag field other than the IXOFF and IXANY flags are cleared in the termios structure). Eight bits of data, with no parity bit are accepted on input and generated on output; the character size is set to CS8 and the PARENB and PARODD flags are cleared in the c_cflag field of the termios structure. The signal-generating and line-editing control characters are disabled by clearing the ISIG and ICANON flags in the c_iflag field of the termios structure.

The CRMOD flag turns input carriage return characters into linefeed characters, and output linefeed characters to be sent as a carriage return followed by a linefeed. The ICRNL flag in the c_iflag field, and the OPOST and ONLCR flags in the c_oflag field, are set in the termios structure.

The LCASE flag maps upper-case letters in the ASCII character set to their lower-case equivalents on input (the IUCLC flag is set in the c_iflag field), and maps lower-case letters in the ASCII character set to their upper-case equivalents on output (the OLCUC flag is set in the c_oflag field). Escape sequences are accepted on input, and generated on output, to handle certain ASCII characters not supported by older terminals (the XCASE flag is set in the c_lflag field).

Other flags are directly mapped to flags in the termios structure:

sg_flags Flags in termios structure

CBREAK Complement of ICANON in c_lflag field

ECHO ECHO in c_lflag field

TANDEM IXOFF in c_iflag field

Another structure associated with each terminal specifies characters that are special in both the old Version 7 and the newer 4BSD terminal interfaces. The following structure is defined by <sys/ttold.h>:

struct tchars {
 char t_intrc; /* interrupt */
 char t_quitc; /* quit */
 char t_startc; /* start output */
 char t_stopc; /* stop output */
 char t_eofc; /* end-of-file */
 char t_brkc; /* input delimiter (like nl) */
 };

XENIX defines the tchar structure as tc. The characters are mapped to members of the c_cc field of the termios structure as follows:

 tchars c_cc index
 t_intrc VINTR
 t_quitc VQUIT
 t_startc VSTART
 t_stopc VSTOP
 t_eofc VEOF
 t_brkc VEOL

Also associated with each terminal is a local flag word (TIOCLSET and TIOCLGET), specifying flags supported by the new 4BSD terminal interface. Most of these flags are directly mapped to flags in the termios structure:

Local flags Flags in termios structure

LCRTBS Not supported

LPRTERA ECHOPRT in the c_lflag field

LCRTERA ECHOE in the c_lflag field

LTILDE Not supported

LMDMBUF Not supported

LTOSTOP TOSTOP in the c_lflag field

LFLUSHO FLUSHO in the c_lflag field

LNOHANG CLOCAL in the c_cflag field

LCRTKIL ECHOKE in the c_lflag field

LPASS8 CS8 in the c_cflag field

LCTLECH CTLECH in the c_lflag field

LPENDIN PENDIN in the c_lflag field

LDECCTQ Complement of IXANY in the c_iflag field

LNOFLSH NOFLSH in the c_lflag field

Each flag has a corresponding equivalent sg_flags value. The sg_flags definitions omit the leading "L"; for example, TIOCSETP with sg_flags set to TOSTOP is equivalent to TIOCLSET with LTOSTOP.

Another structure associated with each terminal is the ltchars structure which defines control characters for the new 4BSD terminal interface. Its structure is:

struct ltchars {
 char t_suspc; /* stop process signal */
 char t_dsuspc; /* delayed stop process signal */
 char t_rprntc; /* reprint line */
 char t_flushc; /*flush output (toggles) */
 char t_werasc; /* word erase */
 char t_lnextc; /* literal next character */
};

The characters are mapped to members of the c_cc field of the termios structure as follows:

ltchars c_cc index

t_suspc VSUS

t_dsuspc VDSUSP

t_rprntc VREPRINT

t_flushc VDISCARD

t_werasc VWERASE

t_lnextc VLNEXT

ttcompat responds to the following ioctl calls. All others are passed to the module below. TIOCGETP

TIOCEXCL TIOCNXCL TIOCSETP TIOCSETN TIOCHPCL TIOCFLUSH TIOCSBRK TIOCCBRK TIOCSDTR TIOCCDTR TIOCSTOP TIOCSTART TIOCGETC TIOCSETC TIOCLGET TIOCLBIS TIOCLBIC TIOCLSET TIOCGLTC TIOCSLTC FIORDCHK FIONREAD

The following ioctls are returned as successful for the sake of compatibility. However, nothing significant is done (that is, the state of the terminal is not changed in any way, and no message is passed through to the underlying tty driver).

DIOCSETP
DIOCSETP
DIOCGETP
LDCLOSE
LDCHG
LDOPEN
LDGETT
LDSETT
TIOCGETD
TIOCSETD

The following old ioctls are not supported by ttcompat, but are supported by Solaris tty drivers. As with all ioctl not otherwise listed in this documentation, these are passed through to the underlying driver and are handled there.

TIOCREMOTE
TIOCGWINSZ
TIOCSWINSZ

The following ioctls are not supported by ttcompat, and are generally not supported by Solaris tty drivers. They are passed through, and the tty drivers return EINVAL.

LDSMAP
LDGMAP
LDNMAP
TIOCNOTTY
TIOCOUTQ

(Note: LDSMAP, LDGMAP, and LDNMAP are defined in <sys/termios.h>.)

ioctl (2), termios (3C), termio (4I), ldterm (4M)