| /* vi: set sw=4 ts=4: */ |
| /* |
| * Utility routines. |
| * |
| * Copyright (C) many different people. |
| * If you wrote this, please acknowledge your work. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #include <stdio.h> |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <unistd.h> |
| #include <sys/ioctl.h> |
| #include "libbb.h" |
| |
| |
| |
| |
| |
| /* From <linux/kd.h> */ |
| static const int KDGKBTYPE = 0x4B33; /* get keyboard type */ |
| static const int KB_84 = 0x01; |
| static const int KB_101 = 0x02; /* this is what we always answer */ |
| |
| static int is_a_console(int fd) |
| { |
| char arg; |
| |
| arg = 0; |
| return (ioctl(fd, KDGKBTYPE, &arg) == 0 |
| && ((arg == KB_101) || (arg == KB_84))); |
| } |
| |
| static int open_a_console(char *fnam) |
| { |
| int fd; |
| |
| /* try read-only */ |
| fd = open(fnam, O_RDWR); |
| |
| /* if failed, try read-only */ |
| if (fd < 0 && errno == EACCES) |
| fd = open(fnam, O_RDONLY); |
| |
| /* if failed, try write-only */ |
| if (fd < 0 && errno == EACCES) |
| fd = open(fnam, O_WRONLY); |
| |
| /* if failed, fail */ |
| if (fd < 0) |
| return -1; |
| |
| /* if not a console, fail */ |
| if (!is_a_console(fd)) { |
| close(fd); |
| return -1; |
| } |
| |
| /* success */ |
| return fd; |
| } |
| |
| /* |
| * Get an fd for use with kbd/console ioctls. |
| * We try several things because opening /dev/console will fail |
| * if someone else used X (which does a chown on /dev/console). |
| * |
| * if tty_name is non-NULL, try this one instead. |
| */ |
| |
| int get_console_fd(void) |
| { |
| int fd; |
| |
| if (-1 == (fd = open_a_console("/dev/console"))) |
| return -1; |
| else |
| return fd; |
| fd = open_a_console(CURRENT_TTY); |
| if (fd >= 0) |
| return fd; |
| |
| fd = open_a_console(CURRENT_VC); |
| if (fd >= 0) |
| return fd; |
| |
| fd = open_a_console(CONSOLE_DEV); |
| if (fd >= 0) |
| return fd; |
| |
| for (fd = 0; fd < 3; fd++) |
| if (is_a_console(fd)) |
| return fd; |
| |
| bb_error_msg("Couldn't get a file descriptor referring to the console"); |
| return -1; /* total failure */ |
| } |
| |
| |
| /* END CODE */ |
| /* |
| Local Variables: |
| c-file-style: "linux" |
| c-basic-offset: 4 |
| tab-width: 4 |
| End: |
| */ |