9.21 gauche.termios - Termios

Module: gauche.termios

This module defines POSIX termios interface, which controls terminal attributes. This module also provides pseudo tty interface, if the system provides it.

Builtin Class: <sys-termios>

POSIX termios(7) structure.

Instance Variable of <sys-termios>: iflag

Instance Variable of <sys-termios>: oflag

Instance Variable of <sys-termios>: cflag

Instance Variable of <sys-termios>: lflag

Instance Variable of <sys-termios>: cc

The slots iflag, oflag, cflag and lflag contains non-negative integers representing bitmasks.

The slot cc contains a copy of c_cc array of struct termios, as an u8vector (see gauche.uvector - Uniform vectors for the details about u8vector). Since cc slot is a copy of the internal structure, you have to set! an u8vector to the slot explicitly to make changes to the c_cc array.

Throughout this section, argument port-or-fd refers to either a port object or a small integer representing system's file descriptor. If port is not associated to the system terminal, an error is signalled. (You can check if port has an associated terminal by sys-isatty?. See section Other file operations).

Function: sys-tcgetattr port-or-fd

Returns terminal parameters in a <sys-termios> object, associated to port-or-fd.

Function: sys-tcsetattr port-or-fd when termios

Sets terminal parameters associated to port-or-fd by termios, which must be an instance of <sys-termios>.

An integer argument when specifies when the changes take effect. Three variables are pre-defined for the argument:

TCSANOW

The change is reflected immediately.

TCSADRAIN

The change is reflected after all pending output is flushed.

TCSAFLUSH

The change is reflected after all pending output is flushed, and all pending input is discarded.

Function: sys-tcsendbreak port-or-fd duration

Transmits a zero stream for the specified duration to the terminal associated to port-or-fd. The unit of duration depends on the system; see man tcsendbreak(3) of your system for details.

Function: sys-tcdrain port-or-fd

Waits until all output written to port-or-fd is transmitted.

Function: sys-tcflush port-or-fd queue

Discards data in the buffer of port-or-fd, specified by queue, which may be one of the following values.

TCIFLUSH

Discards data received but not read.

TCOFLUSH

Discards data written but not transmitted.

TCIOFLUSH

Do both TCIFLUSH and TCOFLUSH action.

Function: sys-tcflow port-or-fd action

Controls data flow of port-or-fd by action, which may be one of the following values:

TCOOFF

Suspends output transmission.

TCOON

Restarts output transmission.

TCIOFF

Transmits a STOP character to make the terminal device stop transmitting data to the system.

TCION

Transmits a START character to make the terminal device resume transmitting data to the system.

Function: sys-tcgetpgrp port-or-fd

Returns process group ID of the terminal associated to port-or-fd.

Function: sys-tcsetpgrp port-or-fd pgrp

Sets process group ID of the terminal associated to port-or-fd to pgrp.

Function: sys-cfgetispeed termios

Function: sys-cfsetispeed termios speed

Function: sys-cfgetospeed termios

Function: sys-cfsetospeed termios speed

Gets/sets input/output speed (baud rate) parameter stored in termios object. Speed is represented by the following predefined numbers: B0, B50, B75, B110, B134, B150, B200, B300, B600, B1200, B1800, B2400, B4800, B9600, B19200, B38400.

Some system may support higher baud rate, such as B57600, B115200 or B230400. You can use symbol-bound? to check these options are defined. B0 is used to terminate the connection.

Function: sys-openpty &optional term

Opens a pair of pseudo ttys, one for master and the other for slave, then returns two integers which are their file descriptors. An optional argument term must be, if passed, a <sys-termios> object; it sets the slave pty's parameters.

You can use open-input-fd-port and/or open-output-fd-port to create a port around the returned file descriptor (See section File ports). To obtain pseudo tty's name, use sys-ttyname (See section Other file operations).

This function is available only if the system supports openpty(3).

Function: sys-forkpty &optional term

Opens a pair of pseudo ttys, one for master and the other for slave, sets the slave pty suitable for login terminal, then fork(2).

Returns two integers; the first value is a child pid for the parent process, and 0 for the child process. The second value is a file descriptor of the master pty.

An optional argument term must be, if passed, a <sys-termios> object; it sets the slave pty's parameters.

This function is available only if the system supports forkpty(3).

Note: sys-forkpty has the same MT hazard as sys-fork (see Unix process management, for details). If you're running multiple threads, use sys-forkpty-and-exec below.

Function: sys-forkpty-and-exec command args &keyword iomap term sigmask

Does sys-forkpty, and lets the child process immediately execs the specified command with arguments args. This function doesn't have the hazard in multi-thread environment.

The meanings of arguments command, args, iomap and sigmask are the same as sys-exec (see Unix process management). If the keyword argument term is given, it is used to initialize the slave pty.

The following example shows how to get a password from the user without echoing:

(use gauche.termios)

(define (get-password prompt)
  (let* ((port (current-input-port))
         (attr (sys-tcgetattr port))
         (lflag (slot-ref attr 'lflag)))
    ;; Show prompt
    (display prompt)
    (flush)
    ;; Turn off echo during reading.
    (dynamic-wind
     (lambda ()
       (slot-set! attr 'lflag (logand lflag (lognot ECHO)))
       (sys-tcsetattr port TCSAFLUSH attr))
     (lambda ()
       (read-line port))
     (lambda ()
       (slot-set! attr 'lflag lflag)
       (sys-tcsetattr port TCSANOW attr)))))

This document was generated by Shiro Kawai on October, 7 2008 using texi2html 1.78.