NAME

ttcompat - V7, 4BSD and XENIX STREAMS compatibility module

SYNOPSIS

#include <sys/stream.h>
#include <sys/stropt.h>
#include <sys/ttcompat.h>
#include <sys/ttold.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  inter-
face  [see termio(7)].  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  automati-
cally pushed onto a stream using the autopush mechanism when
a terminal device is opened; it does not have to  be  expli-
citly  pushed  onto a stream.  This module requires that the
termios interface be supported by the modules and the appli-
cation  can push the driver downstream.  The TCGETS, TCSETS,
and TCSETSF ioctl calls must be supported; if  any  informa-
tion 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
     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, and reflect the values in the
c_cflag field of the termios 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 ter-
mios structure.  The sg_flags field of the  argument  struc-
ture  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  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         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
termios  structure, and the EVENP and ODDP flags control the
parity of characters sent to the terminal and accepted  from
the  terminal:   Parity  is not to be generated on output or
checked on input;
   the character size is set to CS8 and the flag is  cleared
   in the c_cflag field of the termios structure.
Even parity characters are to be  generated  on  output  and
accepted on input;
   the flag is set in  the  c_iflag  field  of  the  termios
   structure,  the character size is set to CS7 and the flag
   is set in the c_cflag field of the termios structure.
Odd parity characters are to  be  generated  on  output  and
accepted on input; the flag is set in the
   c_iflag field, the character size is set to CS7  and  the
   and  flags  are  set  in the c_cflag field of the termios
   structure.
Even parity characters are to be  generated  on  output  and
characters of either parity are to be accepted on input;
   the flag is cleared in the c_iflag field,  the  character
   size  is  set  to  CS7 and the flag is set in the c_cflag
   field of the termios 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 termios structure) and input  pro-
cessing (all flags in the c_iflag field other than the IXOFF
and IXANY flags are cleared in the  termios  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 termios 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  termios
structure.   The  CRMOD  flag  turns input RETURN characters
into NEWLINE characters, and output and echoed NEWLINE char-
acters  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 termios struc-
ture.  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 gen-
erated 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
     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,
specifying  flags  supported by the new 4BSD terminal inter-
face.  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
     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 {
          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     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.

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.

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.

TIOCBRK 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 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.

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 FIORDCHK returns the number of immediately readable characters. The argument is ignored.

FIONREAD FIONREAD returns the number of immediately readable characters in the int pointed to by the argument.

LDSMAP Calls the function emsetmap (tp, mp) if the function is configured in the kernel.

LDGMAP Calls the function emgetmap (tp, mp) if the function is configured in the kernel.

LDNMAP      Calls the function emunmap (tp, mp) if the func-
            tion is configured in the kernel.  The following
            ioctls are returned as successful for  the  sake
            of  compatibility.  However, nothing significant
            is done (i.e., the state of the terminal is  not
            changed in any way).
            TIOCSETD  LDOPEN
            TIOCGETD  LDCLOSE
            DIOCSETP  LDCHG
            DIOCSETP  LDSETT
            DIIOGETP  LDGETT

SEE ALSO

ioctl(2), termios(2), termio(7), ldterm(7).

NOTES

TIOCBRK and TIOCCBRK should be handled by the driver. FIONREAD and FIORDCHK are handled in the stream head.