1/****************************************************************************
2 * Copyright 2020,2021 Thomas E. Dickey                                     *
3 * Copyright 2016,2017 Free Software Foundation, Inc.                       *
4 *                                                                          *
5 * Permission is hereby granted, free of charge, to any person obtaining a  *
6 * copy of this software and associated documentation files (the            *
7 * "Software"), to deal in the Software without restriction, including      *
8 * without limitation the rights to use, copy, modify, merge, publish,      *
9 * distribute, distribute with modifications, sublicense, and/or sell       *
10 * copies of the Software, and to permit persons to whom the Software is    *
11 * furnished to do so, subject to the following conditions:                 *
12 *                                                                          *
13 * The above copyright notice and this permission notice shall be included  *
14 * in all copies or substantial portions of the Software.                   *
15 *                                                                          *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
19 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
20 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
21 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
22 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
23 *                                                                          *
24 * Except as contained in this notice, the name(s) of the above copyright   *
25 * holders shall not be used in advertising or otherwise to promote the     *
26 * sale, use or other dealings in this Software without prior written       *
27 * authorization.                                                           *
28 ****************************************************************************/
29
30/****************************************************************************
31 *  Author: Thomas E. Dickey                                                *
32 ****************************************************************************/
33
34#define USE_LIBTINFO
35#include <tty_settings.h>
36
37#include <fcntl.h>
38
39MODULE_ID("$Id: tty_settings.c,v 1.7 2021/10/08 23:53:32 tom Exp $")
40
41static int my_fd;
42static TTY original_settings;
43static bool can_restore = FALSE;
44
45static void
46failed(const char *msg)
47{
48    int code = errno;
49
50    (void) fprintf(stderr, "%s: %s: %s\n", _nc_progname, msg, strerror(code));
51    restore_tty_settings();
52    (void) fprintf(stderr, "\n");
53    ExitProgram(ErrSystem(code));
54    /* NOTREACHED */
55}
56
57static bool
58get_tty_settings(int fd, TTY * tty_settings)
59{
60    bool success = TRUE;
61    my_fd = fd;
62    if (fd < 0 || GET_TTY(my_fd, tty_settings) < 0) {
63	success = FALSE;
64    }
65    return success;
66}
67
68/*
69 * Open a file descriptor on the current terminal, to obtain its settings.
70 * stderr is less likely to be redirected than stdout; try that first.
71 */
72int
73save_tty_settings(TTY * tty_settings, bool need_tty)
74{
75    if (!get_tty_settings(STDERR_FILENO, tty_settings) &&
76	!get_tty_settings(STDOUT_FILENO, tty_settings) &&
77	!get_tty_settings(STDIN_FILENO, tty_settings)) {
78	if (need_tty) {
79	    int fd = open("/dev/tty", O_RDWR);
80	    if (!get_tty_settings(fd, tty_settings)) {
81		failed("terminal attributes");
82	    }
83	} else {
84	    my_fd = fileno(stdout);
85	}
86    } else {
87	can_restore = TRUE;
88	original_settings = *tty_settings;
89    }
90    return my_fd;
91}
92
93void
94restore_tty_settings(void)
95{
96    if (can_restore)
97	SET_TTY(my_fd, &original_settings);
98}
99
100/* Set the modes if they've changed. */
101void
102update_tty_settings(TTY * old_settings, TTY * new_settings)
103{
104    if (memcmp(new_settings, old_settings, sizeof(TTY))) {
105	SET_TTY(my_fd, new_settings);
106    }
107}
108