TTCOMPAT(4M) TTCOMPAT(4M)


NAME


ttcompat - V7, 4BSD and XENIX STREAMS compatibility module

SYNOPSIS


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


DESCRIPTION


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)
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 termios
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
termios structure, the character size is
set to CS7 and the PARENB flag is set in
the c_iflag field of the termios structure.


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


EVENP|ODDP or ANYP
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_iflag field of the
termios structure.


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 |
+---------+------------+

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. If the speed
is over B38400, then B38400 is returned. The values of
the flags in the sg_flags field are derived from the flags
in the terminal state and stored in the structure.


TIOCEXCL
Set ``exclusive-use'' mode; no further opens are permitted
until the file has been closed.


TIOCNXCL
Turn off ``exclusive-use'' mode.


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. If the current device speed is over B38400 for
either input or output speed, and B38400 is specified
through this interface for that speed, the actual device
speed is not changed. If the device speed is B38400 or
lower or if some speed other than B38400 is specified, then
the actual speed specified is set.


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. (This is not supported by ttcompat. The
underlying driver must support TIOCSBRK.)


TIOCCBRK
The argument is ignored. The break bit is cleared for the
device. (This is not supported by ttcompat. The underlying
driver must support TIOCCBRK.)


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 a 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 a 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. (This ioctl
was added because sg_flags was once a 16 bit value. The
local modes controlled by TIOCLSET are equivalent to the
modes controlled by TIOCSETP and sg_flags.)


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.


FIORDCHK
Returns the number of immediately readable characters. The
argument is ignored. (This ioctl is handled in the stream
head, not in the ttcompat module.)


FIONREAD
Returns the number of immediately readable characters in
the int pointed to by the argument. (This ioctl is handled
in the stream head, not in the ttcompat module.)


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>.)

SEE ALSO


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


October 2, 2001 TTCOMPAT(4M)