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ttcompat(7)

ttcompat -- V7 and 4BSD STREAMS compatibility module

Synopsis

   #include <sys/stream.h>
   #include <sys/stropts.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 and 4BSD terminal drivers into the ioctl calls supported by the termio interface (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 automatically pushed onto a stream with the autopush(1M) 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 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 {
   	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 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 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 

 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:

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 processing (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 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 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 

 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/ioctl.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) */
   };

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 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 

 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 

 ltchars    c_cc index
 t_suspc    VSUSP
 t_dsuspc   VDSUSP
 t_rprntc   VREPRINT
 t_flushc   VDISCARD
 t_werasc   VWERASE
 t_lnextc   VLNEXT

ioctl calls

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 (except by a privileged user) 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 function is configured in the kernel.

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).

TIOCSETD LDOPEN
TIOCGETD LDCLOSE
DIOCSETP LDCHG
DIOCSETP LDSETT
DIIOGETP LDGETT 

 TIOCSETD   LDOPEN
 TIOCGETD   LDCLOSE
 DIOCSETP   LDCHG
 DIOCSETP   LDSETT
 DIIOGETP   LDGETT

References

ioctl(2), ldterm(7), termio(7), termios(3C)

Notices

TIOCBRK and TIOCCBRK should be handled by the driver. FIONREAD and FIORDCHK are handled in the stream head.
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004