| Eric Andersen | aad1a88 | 2001-03-16 22:47:14 +0000 | [diff] [blame] | 1 | /* vi: set sw=4 ts=4: */ |
| 2 | /* |
| 3 | * Utility routines. |
| 4 | * |
| 5 | * Copyright (C) tons of folks. Tracking down who wrote what |
| 6 | * isn't something I'm going to worry about... If you wrote something |
| 7 | * here, please feel free to acknowledge your work. |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License as published by |
| 11 | * the Free Software Foundation; either version 2 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This program is distributed in the hope that it will be useful, |
| 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 17 | * General Public License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU General Public License |
| 20 | * along with this program; if not, write to the Free Software |
| 21 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 22 | * |
| 23 | * Based in part on code from sash, Copyright (c) 1999 by David I. Bell |
| 24 | * Permission has been granted to redistribute this code under the GPL. |
| 25 | * |
| 26 | */ |
| 27 | |
| 28 | #include <stdio.h> |
| 29 | #include <errno.h> |
| 30 | #include <fcntl.h> |
| 31 | #include <unistd.h> |
| 32 | #include <sys/ioctl.h> |
| 33 | #include "libbb.h" |
| 34 | |
| 35 | |
| 36 | |
| 37 | |
| 38 | |
| 39 | /* From <linux/kd.h> */ |
| 40 | static const int KDGKBTYPE = 0x4B33; /* get keyboard type */ |
| 41 | static const int KB_84 = 0x01; |
| 42 | static const int KB_101 = 0x02; /* this is what we always answer */ |
| 43 | |
| 44 | int is_a_console(int fd) |
| 45 | { |
| 46 | char arg; |
| 47 | |
| 48 | arg = 0; |
| 49 | return (ioctl(fd, KDGKBTYPE, &arg) == 0 |
| 50 | && ((arg == KB_101) || (arg == KB_84))); |
| 51 | } |
| 52 | |
| 53 | static int open_a_console(char *fnam) |
| 54 | { |
| 55 | int fd; |
| 56 | |
| 57 | /* try read-only */ |
| 58 | fd = open(fnam, O_RDWR); |
| 59 | |
| 60 | /* if failed, try read-only */ |
| 61 | if (fd < 0 && errno == EACCES) |
| 62 | fd = open(fnam, O_RDONLY); |
| 63 | |
| 64 | /* if failed, try write-only */ |
| 65 | if (fd < 0 && errno == EACCES) |
| 66 | fd = open(fnam, O_WRONLY); |
| 67 | |
| 68 | /* if failed, fail */ |
| 69 | if (fd < 0) |
| 70 | return -1; |
| 71 | |
| 72 | /* if not a console, fail */ |
| 73 | if (!is_a_console(fd)) { |
| 74 | close(fd); |
| 75 | return -1; |
| 76 | } |
| 77 | |
| 78 | /* success */ |
| 79 | return fd; |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * Get an fd for use with kbd/console ioctls. |
| 84 | * We try several things because opening /dev/console will fail |
| 85 | * if someone else used X (which does a chown on /dev/console). |
| 86 | * |
| 87 | * if tty_name is non-NULL, try this one instead. |
| 88 | */ |
| 89 | |
| 90 | int get_console_fd(char *tty_name) |
| 91 | { |
| 92 | int fd; |
| 93 | |
| 94 | if (tty_name) { |
| 95 | if (-1 == (fd = open_a_console(tty_name))) |
| 96 | return -1; |
| 97 | else |
| 98 | return fd; |
| 99 | } |
| 100 | |
| 101 | fd = open_a_console("/dev/tty"); |
| 102 | if (fd >= 0) |
| 103 | return fd; |
| 104 | |
| 105 | fd = open_a_console("/dev/tty0"); |
| 106 | if (fd >= 0) |
| 107 | return fd; |
| 108 | |
| 109 | fd = open_a_console("/dev/console"); |
| 110 | if (fd >= 0) |
| 111 | return fd; |
| 112 | |
| 113 | for (fd = 0; fd < 3; fd++) |
| 114 | if (is_a_console(fd)) |
| 115 | return fd; |
| 116 | |
| 117 | error_msg("Couldnt get a file descriptor referring to the console"); |
| 118 | return -1; /* total failure */ |
| 119 | } |
| 120 | |
| 121 | |
| 122 | /* END CODE */ |
| 123 | /* |
| 124 | Local Variables: |
| 125 | c-file-style: "linux" |
| 126 | c-basic-offset: 4 |
| 127 | tab-width: 4 |
| 128 | End: |
| 129 | */ |