pty/ttymodes.c at master · bluebike/pty · GitHub

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#include "apue.h"
#include <termios.h>
#include <errno.h>

static struct termios save_termios;
static int ttysavefd = -1;
static enum
{ RESET, RAW, CBREAK } ttystate = RESET;

int
tty_cbreak (int fd)		/* put terminal into a cbreak mode */
{
  int err;
  struct termios buf;

  if (ttystate != RESET)
    {
      errno = EINVAL;
      return (-1);
    }
  if (tcgetattr (fd, &buf) < 0)
    return (-1);
  save_termios = buf;		/* structure copy */

  /*
   * Echo off, canonical mode off.
   */
  buf.c_lflag &= ~(ECHO | ICANON);

  /*
   * Case B: 1 byte at a time, no timer.
   */
  buf.c_cc[VMIN] = 1;
  buf.c_cc[VTIME] = 0;
  if (tcsetattr (fd, TCSAFLUSH, &buf) < 0)
    return (-1);

  /*
   * Verify that the changes stuck.  tcsetattr can return 0 on
   * partial success.
   */
  if (tcgetattr (fd, &buf) < 0)
    {
      err = errno;
      tcsetattr (fd, TCSAFLUSH, &save_termios);
      errno = err;
      return (-1);
    }
  if ((buf.c_lflag & (ECHO | ICANON)) || buf.c_cc[VMIN] != 1 ||
      buf.c_cc[VTIME] != 0)
    {
      /*
       * Only some of the changes were made.  Restore the
       * original settings.
       */
      tcsetattr (fd, TCSAFLUSH, &save_termios);
      errno = EINVAL;
      return (-1);
    }

  ttystate = CBREAK;
  ttysavefd = fd;
  return (0);
}

int
tty_raw (int fd)		/* put terminal into a raw mode */
{
  int err;
  struct termios buf;

  if (ttystate != RESET)
    {
      errno = EINVAL;
      return (-1);
    }
  if (tcgetattr (fd, &buf) < 0)
    return (-1);
  save_termios = buf;		/* structure copy */

  /*
   * Echo off, canonical mode off, extended input
   * processing off, signal chars off.
   */
  buf.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);

  /*
   * No SIGINT on BREAK, CR-to-NL off, input parity
   * check off, don't strip 8th bit on input, output
   * flow control off.
   */
  buf.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);

  /*
   * Clear size bits, parity checking off.
   */
  buf.c_cflag &= ~(CSIZE | PARENB);

  /*
   * Set 8 bits/char.
   */
  buf.c_cflag |= CS8;

  /*
   * Output processing off.
   */
  buf.c_oflag &= ~(OPOST);

  /*
   * Case B: 1 byte at a time, no timer.
   */
  buf.c_cc[VMIN] = 1;
  buf.c_cc[VTIME] = 0;
  if (tcsetattr (fd, TCSAFLUSH, &buf) < 0)
    return (-1);

  /*
   * Verify that the changes stuck.  tcsetattr can return 0 on
   * partial success.
   */
  if (tcgetattr (fd, &buf) < 0)
    {
      err = errno;
      tcsetattr (fd, TCSAFLUSH, &save_termios);
      errno = err;
      return (-1);
    }
  if ((buf.c_lflag & (ECHO | ICANON | IEXTEN | ISIG)) ||
      (buf.c_iflag & (BRKINT | ICRNL | INPCK | ISTRIP | IXON)) ||
      (buf.c_cflag & (CSIZE | PARENB | CS8)) != CS8 ||
      (buf.c_oflag & OPOST) || buf.c_cc[VMIN] != 1 || buf.c_cc[VTIME] != 0)
    {
      /*
       * Only some of the changes were made.  Restore the
       * original settings.
       */
      tcsetattr (fd, TCSAFLUSH, &save_termios);
      errno = EINVAL;
      return (-1);
    }

  ttystate = RAW;
  ttysavefd = fd;
  return (0);
}

int
tty_reset (int fd)		/* restore terminal's mode */
{
  if (ttystate == RESET)
    return (0);
  if (tcsetattr (fd, TCSAFLUSH, &save_termios) < 0)
    return (-1);
  ttystate = RESET;
  return (0);
}

void
tty_atexit (void)		/* can be set up by atexit(tty_atexit) */
{
  if (ttysavefd >= 0)
    tty_reset (ttysavefd);
}

struct termios *
tty_termios (void)		/* let caller see original tty state */
{
  return (&save_termios);
}