tty/tty_functions.c

This is tty/tty_functions.c (Listing 62-3, page 1310), an example from the book, The Linux Programming Interface.

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU Lesser General Public License, version 3.

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Function list (Bold in this list means a function is not static)

/* tty_functions.c

   Implement ttySetCbreak() and ttySetRaw().
*/
#include <termios.h>
#include <unistd.h>
#include "tty_functions.h"              /* Declares functions defined here */
/* Place terminal referred to by 'fd' in cbreak mode (noncanonical mode
   with echoing turned off). This function assumes that the terminal is
   currently in cooked mode (i.e., we shouldn't call it if the terminal
   is currently in raw mode, since it does not undo all of the changes
   made by the ttySetRaw() function below). Return 0 on success, or -1
   on error. If 'prevTermios' is non-NULL, then use the buffer to which
   it points to return the previous terminal settings. */

int
ttySetCbreak(int fd, struct termios *prevTermios)
{
    struct termios t;

    if (tcgetattr(fd, &t) == -1)
        return -1;

    if (prevTermios != NULL)
        *prevTermios = t;

    t.c_lflag &= ~(ICANON | ECHO);
    t.c_lflag |= ISIG;

    t.c_iflag &= ~ICRNL;

    t.c_cc[VMIN] = 1;                   /* Character-at-a-time input */
    t.c_cc[VTIME] = 0;                  /* with blocking */

    if (tcsetattr(fd, TCSAFLUSH, &t) == -1)
        return -1;

    return 0;
}
/* Place terminal referred to by 'fd' in raw mode (noncanonical mode
   with all input and output processing disabled). Return 0 on success,
   or -1 on error. If 'prevTermios' is non-NULL, then use the buffer to
   which it points to return the previous terminal settings. */

int
ttySetRaw(int fd, struct termios *prevTermios)
{
    struct termios t;

    if (tcgetattr(fd, &t) == -1)
        return -1;

    if (prevTermios != NULL)
        *prevTermios = t;

    t.c_lflag &= ~(ICANON | ISIG | IEXTEN | ECHO);
                        /* Noncanonical mode, disable signals, extended
                           input processing, and echoing */

    t.c_iflag &= ~(BRKINT | ICRNL | IGNBRK | IGNCR | INLCR |
                      INPCK | ISTRIP | IXON | PARMRK);
                        /* Disable special handling of CR, NL, and BREAK.
                           No 8th-bit stripping or parity error handling.
                           Disable START/STOP output flow control. */

    t.c_oflag &= ~OPOST;                /* Disable all output processing */

    t.c_cc[VMIN] = 1;                   /* Character-at-a-time input */
    t.c_cc[VTIME] = 0;                  /* with blocking */

    if (tcsetattr(fd, TCSAFLUSH, &t) == -1)
        return -1;

    return 0;
}

 

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