TTCOMPAT(4M) — DEVICES AND NETWORK INTERFACES

NAME

ttcompat − V7 and 4BSD STREAMS compatibility module

CONFIG

None; included by default.

SYNOPSIS

#include <sys/types.h>
#include <sys/stream.h>
#include <sys/stropts.h>

ioctl(fd, I_PUSH, "ttcompat");

DESCRIPTION

ttcompat is a STREAMS module that translates the ioctl calls supported by the older Version 7 and 4BSD terminal drivers into the ioctl calls supported by the termio(4) interface. 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.

Normally, this module is automatically pushed onto a stream when a terminal device is opened; it does not have to be explicitly pushed onto a stream. This module requires that the termio interface be supported by the modules and 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 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/ioctl.h>:

struct sgttyb {
charsg_ispeed;
charsg_ospeed;
charsg_erase;
charsg_kill;
shortsg_flags;
};

The sg_ispeed and sg_ospeed fields describe the input and output speeds of the device, and reflect the values in the c_cflag field of the termio structure. 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 termio 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 termio structure.

Delay type 0 is always mapped into the equivalent delay type 0 in the c_oflag field of the termio structure. Other delay mappings are performed as follows:

sg_flags c_oflag

BS1 BS1

FF1 VT1

CR1 CR2

CR2 CR3

CR3 not supported

TAB1 TAB1

TAB2 TAB2

XTABS TAB3

NL1 ONLRET|CR1

NL2 NL1

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 termio structure, and the EVENP and ODDP flags control the parity of characters sent to the terminal and accepted from the terminal:

0 Parity is not to be generated on output or checked on input; the character size is set to CS8 and the PARENB flag is cleared in the c_cflag field of the termio structure.

EVENP Even parity characters are to be generated on output and accepted on input; the INPCK flag is set in the c_iflag field of the termio structure, the character size is set to CS7 and the PARENB flag is set in the c_cflag field of the termio structure.

ODDP Odd parity characters are to be generated on output and accepted on input; the INPCK flag is set in the c_iflag field, the character size is set to CS7 and the PARENB and PARODD flags are set in the c_cflag field of the termio structure.

EVENP|ODDP
Even parity characters are to be generated on output and characters of either parity are to be accepted on input; the INPCK flag is cleared in the c_iflag field, the character size is set to CS7 and the PARENB flag is set in the c_cflag field of the termio structure.

The RAW flag disables all output processing (the OPOST flag in the c_oflag field, and the XCASE flag in the c_lflag field, are cleared in the termio structure) and input processing (all flags in the c_iflag field other than the IXOFF and IXANY flags are cleared in the termio structure). 8 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 termio structure. The signal-generating and line-editing control characters are disabled by clearing the ISIG and ICANON flags in the c_lflag field of the termio structure.

The CRMOD flag turn input RETURN characters into NEWLINE characters, and output and echoed NEWLINE characters to be output as a 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 termio 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 termio structure:

sg_flags flags in termio 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/ioctl.h>:

struct tchars {
chart_intrc;/∗ interrupt ∗/
chart_quitc;/∗ quit ∗/
chart_startc;/∗ start output ∗/
chart_stopc;/∗ stop output ∗/
chart_eofc;/∗ end-of-file ∗/
chart_brkc;/∗ input delimiter (like nl) ∗/
};

The characters are mapped to members of the c_cc field of the termio 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, specifying flags supported by the new 4BSD terminal interface. Most of these flags are directly mapped to flags in the termio structure:

local flags flags in termio structure

LCRTBS not supported

LPRTERA ECHOPRT in the c_lflag field

LCRTERA ECHOE in the c_lflag field

LTILDE 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

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

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 {
chart_suspc;/∗ stop process signal ∗/
chart_dsuspc;/∗ delayed stop process signal ∗/
chart_rprntc;/∗ reprint line ∗/
chart_flushc;/∗ flush output (toggles) ∗/
chart_werasc;/∗ word erase ∗/
chart_lnextc;/∗ literal next character ∗/
};

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

ltchars c_cc index

t_suspc VSUSP

t_dsuspc VDSUSP

t_rprntc VREPRINT

t_flushc VDISCARD

t_werasc VWERASE

t_lnextc VLNEXT

IOCTLS

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

TIOCGETP
The argument is a pointer to an sgttyb structure. The current terminal state is fetched; the appropriate characters in the terminal state are stored in that structure, as are the input and output speeds. The values of the flags in the sg_flags field are derived from the flags in the terminal state and stored in the structure.

TIOCSETP The argument is a pointer to an sgttyb structure. The appropriate characters and input and output speeds in the terminal state are set from the values in that structure, and the flags in the terminal state are set to match the values of the flags in the sg_flags field of that structure. The state is changed with a TCSETSF ioctl, so that the interface delays until output is quiescent, then throws away any unread characters, before changing the modes.

TIOCSETN The argument is a pointer to an sgttyb structure. The terminal state is changed as TIOCSETP would change it, but a TCSETS ioctl is used, so that the interface neither delays nor discards input.

TIOCHPCL The argument is ignored. The HUPCL flag is set in the c_cflag word of the terminal state.

TIOCFLUSH
The argument is a pointer to an int variable. If its value is zero, all characters waiting in input or output queues are flushed. Otherwise, the value of the int is treated as the logical OR of the FREAD and FWRITE flags defined by <sys/file.h>; if the FREAD bit is set, all characters waiting in input queues are flushed, and if the FWRITE bit is set, all characters waiting in output queues are flushed.

TIOCSBRK The argument is ignored. The break bit is set for the device.

TIOCCBRK
The argument is ignored. The break bit is cleared for the device.

TIOCSDTR The argument is ignored. The Data Terminal Ready bit is set for the device.

TIOCCDTR
The argument is ignored. The Data Terminal Ready bit is cleared for the device.

TIOCSTOP The argument is ignored. Output is stopped as if the STOP character had been typed.

TIOCSTART
The argument is ignored. Output is restarted as if the START character had been typed.

TIOCGETC
The argument is a pointer to an tchars structure. The current terminal state is fetched, and the appropriate characters in the terminal state are stored in that structure.

TIOCSETC The argument is a pointer to an tchars structure. The values of the appropriate characters in the terminal state are set from the characters in that structure.

TIOCLGET The argument is a pointer to an int. The current terminal state is fetched, and the values of the local flags are derived from the flags in the terminal state and stored in the int pointed to by the argument.

TIOCLBIS The argument is a pointer to an int whose value is a mask containing flags to be set in the local flags word. The current terminal state is fetched, and the values of the local flags are derived from the flags in the terminal state; the specified flags are set, and the flags in the terminal state are set to match the new value of the local flags word.

TIOCLBIC The argument is a pointer to an int whose value is a mask containing flags to be cleared in the local flags word. The current terminal state is fetched, and the values of the local flags are derived from the flags in the terminal state; the specified flags are cleared, and the flags in the terminal state are set to match the new value of the local flags word.

TIOCLSET The argument is a pointer to an int containing a new set of local flags. The flags in the terminal state are set to match the new value of the local flags word.

TIOCGLTC The argument is a pointer to an ltchars structure. The values of the appropriate characters in the terminal state are stored in that structure.

TIOCSLTC The argument is a pointer to an ltchars structure. The values of the appropriate characters in the terminal state are set from the characters in that structure.

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