1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) many different people. If you wrote this, please
6 * acknowledge your work.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27 #include <sys/ioctl.h>
34 /* From <linux/kd.h> */
35 static const int KDGKBTYPE = 0x4B33; /* get keyboard type */
36 static const int KB_84 = 0x01;
37 static const int KB_101 = 0x02; /* this is what we always answer */
39 static int is_a_console(int fd)
44 return (ioctl(fd, KDGKBTYPE, &arg) == 0
45 && ((arg == KB_101) || (arg == KB_84)));
48 static int open_a_console(char *fnam)
53 fd = open(fnam, O_RDWR);
55 /* if failed, try read-only */
56 if (fd < 0 && errno == EACCES)
57 fd = open(fnam, O_RDONLY);
59 /* if failed, try write-only */
60 if (fd < 0 && errno == EACCES)
61 fd = open(fnam, O_WRONLY);
67 /* if not a console, fail */
68 if (!is_a_console(fd)) {
78 * Get an fd for use with kbd/console ioctls.
79 * We try several things because opening /dev/console will fail
80 * if someone else used X (which does a chown on /dev/console).
82 * if tty_name is non-NULL, try this one instead.
85 int get_console_fd(void)
89 if (-1 == (fd = open_a_console("/dev/console")))
93 fd = open_a_console(CURRENT_TTY);
97 fd = open_a_console(CURRENT_VC);
101 fd = open_a_console(CONSOLE_DEV);
105 for (fd = 0; fd < 3; fd++)
106 if (is_a_console(fd))
109 error_msg("Couldn't get a file descriptor referring to the console");
110 return -1; /* total failure */
117 c-file-style: "linux"