1  /* Noncanonical Mode Example
       2     Copyright (C) 1991-2023 Free Software Foundation, Inc.
       3  
       4     This program is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU General Public License
       6     as published by the Free Software Foundation; either version 2
       7     of the License, or (at your option) any later version.
       8  
       9     This program is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      12     GNU General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program; if not, see <https://www.gnu.org/licenses/>.
      16  */
      17  
      18  #include <unistd.h>
      19  #include <stdio.h>
      20  #include <stdlib.h>
      21  #include <termios.h>
      22  
      23  /* Use this variable to remember original terminal attributes. */
      24  
      25  struct termios saved_attributes;
      26  
      27  void
      28  reset_input_mode (void)
      29  {
      30    tcsetattr (STDIN_FILENO, TCSANOW, &saved_attributes);
      31  }
      32  
      33  void
      34  set_input_mode (void)
      35  {
      36    struct termios tattr;
      37    char *name;
      38  
      39    /* Make sure stdin is a terminal. */
      40    if (!isatty (STDIN_FILENO))
      41      {
      42        fprintf (stderr, "Not a terminal.\n");
      43        exit (EXIT_FAILURE);
      44      }
      45  
      46    /* Save the terminal attributes so we can restore them later. */
      47    tcgetattr (STDIN_FILENO, &saved_attributes);
      48    atexit (reset_input_mode);
      49  
      50  /*@group*/
      51    /* Set the funny terminal modes. */
      52    tcgetattr (STDIN_FILENO, &tattr);
      53    tattr.c_lflag &= ~(ICANON|ECHO); /* Clear ICANON and ECHO.  */
      54    tattr.c_cc[VMIN] = 1;
      55    tattr.c_cc[VTIME] = 0;
      56    tcsetattr (STDIN_FILENO, TCSAFLUSH, &tattr);
      57  }
      58  /*@end group*/
      59  
      60  int
      61  main (void)
      62  {
      63    char c;
      64  
      65    set_input_mode ();
      66  
      67    while (1)
      68      {
      69        read (STDIN_FILENO, &c, 1);
      70        if (c == '\004')		/* @kbd{C-d} */
      71  	break;
      72        else
      73  	putchar (c);
      74      }
      75  
      76    return EXIT_SUCCESS;
      77  }