ncurses 6.0 - patch 20161224
[ncurses.git] / progs / tty_settings.c
1 /****************************************************************************
2  * Copyright (c) 2016 Free Software Foundation, Inc.                        *
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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 }