progs/tty_settings.c

   1 /****************************************************************************
   2  * Copyright (c) 2016 Free Software Foundation, Inc.                        *
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  11  *                                                                          *
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  13  * in all copies or substantial portions of the Software.                   *
  14  *                                                                          *
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  27  ****************************************************************************/
  28
  29 /****************************************************************************
  30  *  Author: Thomas E. Dickey                                                *
  31  ****************************************************************************/
  32
  33 #define USE_LIBTINFO
  34 #include <tty_settings.h>
  35
  36 #include <fcntl.h>
  37
  38 MODULE_ID("$Id: tty_settings.c,v 1.2 2016/12/24 19:31:11 tom Exp $")
  39
  40 static int my_fd;
  41 static TTY original_settings;
  42 static bool can_restore = FALSE;
  43
  44 static void
  45 exit_error(void)
  46 {
  47     restore_tty_settings();
  48     (void) fprintf(stderr, "\n");
  49     ExitProgram(EXIT_FAILURE);
  50     /* NOTREACHED */
  51 }
  52
  53 static void
  54 failed(const char *msg)
  55 {
  56     char temp[BUFSIZ];
  57
  58     _nc_STRCPY(temp, _nc_progname, sizeof(temp));
  59     _nc_STRCAT(temp, ": ", sizeof(temp));
  60     _nc_STRNCAT(temp, msg, sizeof(temp), sizeof(temp) - strlen(temp) - 2);
  61     perror(temp);
  62     exit_error();
  63     /* NOTREACHED */
  64 }
  65
  66 static bool
  67 get_tty_settings(int fd, TTY * tty_settings)
  68 {
  69     bool success = TRUE;
  70     my_fd = fd;
  71     if (fd < 0 || GET_TTY(my_fd, tty_settings) < 0) {
  72         success = FALSE;
  73     }
  74     return success;
  75 }
  76
  77 /*
  78  * Open a file descriptor on the current terminal, to obtain its settings.
  79  * stderr is less likely to be redirected than stdout; try that first.
  80  */
  81 int
  82 save_tty_settings(TTY * tty_settings)
  83 {
  84     if (!get_tty_settings(STDERR_FILENO, tty_settings) &&
  85         !get_tty_settings(STDOUT_FILENO, tty_settings) &&
  86         !get_tty_settings(STDIN_FILENO, tty_settings) &&
  87         !get_tty_settings(open("/dev/tty", O_RDWR), tty_settings)) {
  88         failed("terminal attributes");
  89     }
  90     can_restore = TRUE;
  91     original_settings = *tty_settings;
  92     return my_fd;
  93 }
  94
  95 void
  96 restore_tty_settings(void)
  97 {
  98     if (can_restore)
  99         SET_TTY(my_fd, &original_settings);
 100 }
 101
 102 /* Set the modes if they've changed. */
 103 void
 104 update_tty_settings(TTY * old_settings, TTY * new_settings)
 105 {
 106     if (memcmp(new_settings, old_settings, sizeof(TTY))) {
 107         SET_TTY(my_fd, new_settings);
 108     }
 109 }